Solved: The pH Scale (Section)Consider two solutions,

(a) Identify the BrnstedLowry acid and base in the reaction + + = H = N = Cl +

(b) Identify the Lewis acid and base in the reaction. [Sections 16.2 and 16.11]

The following diagrams represent aqueous solutions of two monoprotic acids, HA 1A = X or Y2. The water molecules have been omitted for clarity. (a) Which is the stronger acid, HX or HY? (b) Which is the stronger base, X- or Y-? (c) If you mix equal concentrations of HX and NaY, will the equilibrium HX1aq2 + Y-1aq2 HY1aq2 + X-1aq2 lie mostly to the right 1Kc 7 12 or to the left 1Kc 6 12? [Section 16.2] HX HY = HA = A = H 3O+

The indicator methyl orange has been added to both of the following solutions. Based on the colors, classify each statement as true or false: (a) The pH of solution A is definitely less than 7.00. (b) The pH of solution B is definitely greater than 7.00. (c) The pH of solution B is greater than that of solution A. [Section 16.4] Solution A Solution B

The probe of the pH meter shown here is sitting in a beaker that contains a clear liquid. (a) You are told the liquid is pure water, a solution of HCl(aq), or a solution of KOH(aq). Which one is it? (b) If the liquid is one of the solutions, what is its molarity? (c) Why is the temperature given on the pH meter? [Sections 16.4 and 16.5]

The following diagrams represent aqueous solutions of three acids, HX, HY, and HZ. The water molecules have been omitted for clarity, and the hydrated proton is represented as H+ rather than H3O+. (a) Which of the acids is a strong acid? Explain. (b) Which acid would have the smallest acid- dissociation constant, Ka? (c) Which solution would have the highest pH? [Sections 16.5 and 16.6] HX HY HZ + + + + + + + + + + + + +

The graph given below shows 3H+4 vs. concentration for an aqueous solution of an unknown substance. (a) Is the substance a strong acid, a weak acid, a strong base, or a weak base? (b) Based on your answer to (a), can you determine the value of the pH of the solution when the concentration is 0.18 M? (c) Would the line go exactly through the origin of the plot? [Sections 16.5 and 16.6] 0 0 0.060 0.12 Concentration (M) 0.18 [H+]

(a) Which of these three lines represents the effect of concentration on the percent ionization of a weak acid?

(b) Explain in qualitative terms why the curve you chose has the shape it does. [Section 16.6] Acid concentration 0 0 Percent ionized C B A

Each of the three molecules shown here contains an OH group, but one molecule acts as a base, one as an acid, and the third is neither acid nor base. (a) Which one acts as a base? Why does only this molecule act as a base? (b) Which one acts as an acid? (c) Why is the remaining molecule neither acidic nor basic? [Sections 16.6 and 16.7] Molecule A Molecule B Molecule C Molecule A Molecule B Molecule C

Phenylephrine, an organic substance with molecular formula C9H13NO2, is used as a nasal decongenstant in over-thecounter medications. The molecular structure of phenylephrine is shown below using the usual shortcut organic nomenclature. (a) Would you expect a solution of phenylephrine to be acidic, neutral, or basic? (b) One of the active ingredients in Alka-Seltzer PLUS cold medication is phenylephrine hydrochloride. How does this ingredient differ from the structure shown below? (c) Would you expect a solution of phenylephrine hydrochloride to be acidic, neutral, or basic? [Sections 16.8 and 16.9] CH3 H N OH HO

Which of the following diagrams best represents an aqueous solution of NaF? (For clarity, the water molecules are not shown.) Will this solution be acidic, neutral, or basic? [Section 16.9] Solution A Na+ F OH HF Solution B Solution C + + + + + + + + + + + + + + + + +

Consider the molecular models shown here, where X represents a halogen atom. (a) If X is the same atom in both molecules, which molecule will be more acidic? (b) Does the acidity of each molecule increase or decrease as the electronegativity of the atom X increases? [Section 16.10] (a) (b) O O X H C O H X

(a) The following diagram represents the reaction of PCl4 + with Cl -. Draw the Lewis structures for the reactants and products, and identify the Lewis acid and the Lewis base in the reaction. + +

(b) The following reaction represents a hydrated cation losing a proton. How does the equilibrium constant for the reaction change as the charge of the cation increases? [Sections 16.9 and 16.11] + + (n1)+ + n+

(a) What is the difference between the Arrhenius and the BrnstedLowry definitions of an acid?

(b) NH31g2 and HCl(g) react to form the ionic solid NH4Cl1s2. Which substance is the BrnstedLowry acid in this reaction? Which is the BrnstedLowry base?

(a) What is the difference between the Arrhenius and the BrnstedLowry definitions of a base?

(b) Can a substance behave as an Arrhenius base if it does not contain an OH group? Explain

a) Give the conjugate base of the following BrnstedLowry acids: (i) HIO3, (ii) NH4 +.

(b) Give the conjugate acid of the following BrnstedLowry bases: (i) O2-, (ii) H2PO4 -

(a) Give the conjugate base of the following BrnstedLowry acids: (i) HCOOH, (ii) HPO4 2-

(b) Give the conjugate acid of the following BrnstedLowry bases: (i) SO4 2-, (ii) CH3NH2.

Designate the BrnstedLowry acid and the BrnstedLowry base on the left side of each of the following equations, and also designate the conjugate acid and conjugate base of each on the right side: (a) NH4 +1aq2 + CN-1aq2 HCN1aq2 + NH31aq2 (b) 1CH323N1aq2 + H2O1l2 1CH323NH+1aq2 + OH- 1aq2 (c) HCOOH1aq2 + PO4 3-1aq2 HCOO-1aq2 + HPO4 2-1aq2

Designate the BrnstedLowry acid and the BrnstedLowry base on the left side of each equation, and also designate the conjugate acid and conjugate base of each on the right side. (a) HBrO1aq2 + H2O1l2 H3O+1aq2 + BrO-1aq2 (b) HSO4 -1aq2 + HCO3 -1aq2 SO4 2 - 1aq2 + H2CO31aq2 (c) HSO3 -1aq2 + H3O+1aq2 H2SO31aq2 + H2O1l2

(a) The hydrogen sulfite ion 1HSO3 -2 is amphiprotic. Write a balanced chemical equation showing how it acts as an acid toward water and another equation showing how it acts as a base toward water.

(b) What is the conjugate acid of HSO3 -? What is its conjugate base?

(a) Write an equation for the reaction in which H2C6H7O5 -1aq2 acts as a base in H2O1l2.

(b) Write an equation for the reaction in which H2C6H7O5 -1aq2 acts as an acid in H2O1l2.

(c) What is the conjugate acid of H2C6H7O5 -1aq2? What is its conjugate base?

Label each of the following as being a strong base, a weak base, or a species with negligible basicity. In each case write the formula of its conjugate acid, and indicate whether the conjugate acid is a strong acid, a weak acid, or a species with negligible acidity: (a) CH3COO-, (b) HCO3 -, (c) O2-, (d) Cl -, (e) NH3.

Label each of the following as being a strong acid, a weak acid, or a species with negligible acidity. In each case write the formula of its conjugate base, and indicate whether the conjugate base is a strong base, a weak base, or a species with negligible basicity: (a) HCOOH, (b) H2, (c) CH4, (d) HF, (e) NH4 +.

(a) Which of the following is the stronger BrnstedLowry acid, HBrO or HBr?

(b) Which is the stronger Brnsted Lowry base, F- or Cl -?

(a) Which of the following is the stronger BrnstedLowry acid, HClO3 or HClO2?

(b) Which is the stronger Brnsted Lowry base, HS- or HSO4 -?

Predict the products of the following acidbase reactions, and predict whether the equilibrium lies to the left or to the right of the equation: (a) O2-1aq2 + H2O1l2 (b) CH3COOH1aq2 + HS-1aq2 (c) NO2 -1aq2 + H2O1l2

Predict the products of the following acidbase reactions, and predict whether the equilibrium lies to the left or to the right of the equation: (a) NH4 +1aq2 + OH-1aq2 (b) CH3COO-1aq2 + H3O+1aq2 (c) HCO3 -1aq2 + F-1aq2

If a neutral solution of water, with pH = 7.00, is cooled to 10 C, the pH rises to 7.27. Which of the following three statements is correct for the cooled water: (i) 3H+4 7 3OH-4, (ii) 3H+4 = 3OH-4, or (iii) 3H+4 6 3OH-4?

(a) Write a chemical equation that illustrates the autoionization of water.

(b) Write the expression for the ion-product constant for water, Kw. (c) If a solution is described as basic, which of the following is true: (i) 3H+4 7 3OH-4, (ii) 3H+4 = 3OH-4, or (iii) 3H+4 6 3OH-4?

Calculate 3H+4 for each of the following solutions, and indicate whether the solution is acidic, basic, or neutral: (a) 3OH-4 = 0.00045 M; (b) 3OH-4 = 8.8 * 10-9 M; (c) a solution in which 3OH-4 is 100 times greater than 3H+4.

Calculate 3OH-4 for each of the following solutions, and indicate whether the solution is acidic, basic, or neutral: (a) 3H+4 = 0.0505 M; (b) 3H+4 = 2.5 * 10-10 M; (c) a solution in which 3H+4 is 1000 times greater than 3OH-4.

At the freezing point of water 10 C2, Kw = 1.2 * 10-15 . Calculate 3H+4 and 3OH-4 for a neutral solution at this temperature

Deuterium oxide 1D2O, where D is deuterium, the hydrogen-2 isotope) has an ion-product constant, Kw, of 8.9 * 10-16 at 20 C. Calculate 3D+4 and 3OD-4 for pure (neutral) D2O at this temperature.

By what factor does 3H+4 change for a pH change of (a) 2.00 units, (b) 0.50 units?

Consider two solutions, solution A and solution B. 3H+4 in solution A is 250 times greater than that in solution B. What is the difference in the pH values of the two solutions?

Complete the following table by calculating the missing entries and indicating whether the solution is acidic or basic. 3h+ 4 oh 1aq2 ph poh Acidic or Basic? 7.5 * 10-3 M 3.6 * 10-10 M 8.25 5.70

Complete the following table by calculating the missing entries. In each case indicate whether the solution is acidic or basic. ph poh 3h+ 4 3oh 4 Acidic or Basic? 5.25 2.02 4.4 * 10-10 M 8.5 * 10-2 M

The average pH of normal arterial blood is 7.40. At normal body temperature 137 C2, Kw = 2.4 * 10- 14 . Calculate 3H+4, 3OH-4, and pOH for blood at this temperature

Carbon dioxide in the atmosphere dissolves in raindrops to produce carbonic acid 1H2CO32, causing the pH of clean, unpolluted rain to range from about 5.2 to 5.6. What are the ranges of 3H+4 and 3OH-4 in the raindrops?

Addition of the indicator methyl orange to an unknown solution leads to a yellow color. The addition of bromthymol blue to the same solution also leads to a yellow color. (a) Is the solution acidic, neutral, or basic? (b) What is the range (in whole numbers) of possible pH values for the solution? (c) Is there another indicator you could use to narrow the range of possible pH values for the solution?

Addition of phenolphthalein to an unknown colorless solution does not cause a color change. The addition of bromthymol blue to the same solution leads to a yellow color. (a) Is the solution acidic, neutral, or basic? (b) Which of the following can you establish about the solution: (i) A minimum pH, (ii) A maximum pH, or (iii) A specific range of pH values? (c) What other indicator or indicators would you want to use to determine the pH of the solution more precisely?

Is each of the following statements true or false? (a) All strong acids contain one or more H atoms. (b) A strong acid is a strong electrolyte. (c) A 1.0-M solution of a strong acid will have pH = 1.0.

Determine whether each of the following is true or false: (a) All strong bases are salts of the hydroxide ion. (b) The addition of a strong base to water produces a solution of pH 7 7.0. (c) Because Mg1OH22 is not very soluble, it cannot be a strong base.

Calculate the pH of each of the following strong acid solutions: (a) 8.5 * 10-3 M HBr, (b) 1.52 g of HNO3 in 575 mL of solution, (c) 5.00 mL of 0.250 M HClO4 diluted to 50.0 mL, (d) a solution formed by mixing 10.0 mL of 0.100 M HBr with 20.0 mL of 0.200 M HCl.

Calculate the pH of each of the following strong acid solutions: (a) 0.0167 M HNO3, (b) 0.225 g of HClO3 in 2.00 L of solution, (c) 15.00 mL of 1.00 M HCl diluted to 0.500 L, (d) a mixture formed by adding 50.0 mL of 0.020 M HCl to 125 mL of 0.010 M HI.

Calculate 3OH-4 and pH for (a) 1.5 * 10-3 M Sr1OH22, (b) 2.250 g of LiOH in 250.0 mL of solution, (c) 1.00 mL of 0.175 M NaOH diluted to 2.00 L, (d) a solution formed by adding 5.00 mL of 0.105 M KOH to 15.0 mL of 9.5 * 10-2 M Ca1OH22.

Calculate 3OH-4 and pH for each of the following strong base solutions: (a) 0.182 M KOH, (b) 3.165 g of KOH in 500.0 mL of solution, (c) 10.0 mL of 0.0105 MCa1OH22 diluted to 500.0 mL, (d) a solution formed by mixing 20.0 mL of 0.015 M Ba1OH22 with 40.0 mL of 8.2 * 10-3 M NaOH.

Calculate the concentration of an aqueous solution of NaOH that has a pH of 11.50.

Calculate the concentration of an aqueous solution of Ca1OH22 that has a pH of 10.05.

Write the chemical equation and the Ka expression for the ionization of each of the following acids in aqueous solution. First show the reaction with H+1aq2 as a product and then with the hydronium ion: (a) HBrO2, (b) C2H5COOH

Write the chemical equation and the Ka expression for the acid dissociation of each of the following acids in aqueous solution. First show the reaction with H+1aq2 as a product and then with the hydronium ion: (a) C6H5COOH, (b) HCO3 -.

Lactic acid 1CH3CH(OH2COOH) has one acidic hydrogen. A 0.10 M solution of lactic acid has a pH of 2.44. Calculate Ka.

Phenylacetic acid 1C6H5CH2COOH2 is one of the substances that accumulates in the blood of people with phenylketonuria, an inherited disorder that can cause mental retardation or even death. A 0.085 M solution of C6H5CH2COOH has a pH of 2.68. Calculate the Ka value for this acid.

A 0.100 M solution of chloroacetic acid 1ClCH2COOH2 is 11.0% ionized. Using this information, calculate 3ClCH2COO-4, 3H+4, 3ClCH2COOH4, and Ka for chloroacetic acid.

A 0.100 M solution of bromoacetic acid 1BrCH2COOH2 is 13.2% ionized. Calculate 3H+4, 3BrCH2COO-4, 3BrCH2COOH4 and Ka for bromoacetic acid.

A particular sample of vinegar has a pH of 2.90. If acetic acid is the only acid that vinegar contains 1Ka = 1.8 * 10-5 2, calculate the concentration of acetic acid in the vinegar.

If a solution of HF 1Ka = 6.8 * 10-4 2 has a pH of 3.65, calculate the concentration of hydrofluoric acid.

The acid-dissociation constant for benzoic acid 1C6H5COOH2 is 6.3 * 10-5 . Calculate the equilibrium concentrations of H3O+, C6H5COO-, and C6H5COOH in the solution if the initial concentration of C6H5COOH is 0.050 M

The acid-dissociation constant for chlorous acid 1HClO22 is 1.1 * 10-2 . Calculate the concentrations of H3O+, ClO2 -, and HClO2 at equilibrium if the initial concentration of HClO2 is 0.0125 M.

Calculate the pH of each of the following solutions (Ka and Kb values are given in Appendix D): (a) 0.095 M propionic acid 1C2H5COOH2, (b) 0.100 M hydrogen chromate ion 1HCrO4 -2, (c) 0.120 M pyridine 1C5H5N2.

Determine the pH of each of the following solutions (Ka and Kb values are given in Appendix D): (a) 0.095 M hypochlorous acid, (b) 0.0085 M hydrazine, (c) 0.165 M hydroxylamine.

Saccharin, a sugar substitute, is a weak acid with pKa = 2.32 at 25 C. It ionizes in aqueous solution as follows: HNC7H4SO31aq2 H+1aq2 + NC7H4SO3 -1aq2 What is the pH of a 0.10 M solution of this substance?

The active ingredient in aspirin is acetylsalicylic acid 1HC9H7O42, a monoprotic acid with Ka = 3.3 * 10-4 at 25 C. What is the pH of a solution obtained by dissolving two extra-strength aspirin tablets, containing 500 mg of acetylsalicylic acid each, in 250 mL of water?

Calculate the percent ionization of hydrazoic acid 1HN32 in solutions of each of the following concentrations (Ka is given in Appendix D): (a) 0.400 M, (b) 0.100 M, (c) 0.0400 M.

Calculate the percent ionization of propionic acid 1C2H5COOH2 in solutions of each of the following concentrations 1Ka is given in Appendix D): (a) 0.250 M, (b) 0.0800 M, (c) 0.0200 M.

Citric acid, which is present in citrus fruits, is a triprotic acid (Table 16.3). (a) Calculate the pH of a 0.040 M solution of citric acid. (b) Did you have to make any approximations or assumptions in completing your calculations? (c) Is the concentration of citrate ion 1C6H5O7 3-2 equal to, less than, or greater than the H+ ion concentration?

Tartaric acid is found in many fruits, including grapes, and is partially responsible for the dry texture of certain wines. Calculate the pH and the tartrate ion 1C4H4O6 2-2 concentration for a 0.250 M solution of tartaric acid, for which the acid-dissociation constants are listed in Table 16.3. Did you have to make any approximations or assumptions in your calculation?

Consider the base hydroxylamine, NH2OH. (a) What is the conjugate acid of hydroxylamine? (b) When it acts as a base, which atom in hydroxylamine accepts a proton? (c) There are two atoms in hydroxylamine that have nonbonding electron pairs that could act as proton acceptors. Use Lewis structures and formal charges (Section 8.5) to rationalize why one of these two atoms is a much better proton acceptor than the other.

The hypochlorite ion, ClO-, acts as a weak base. (a) Is ClO- a stronger or weaker base than hydroxylamine? (b) When ClOacts as a base, which atom, Cl or O, acts as the proton acceptor? (c) Can you use formal charges to rationalize your answer to part (b)?

Write the chemical equation and the Kb expression for the reaction of each of the following bases with water: (a) dimethylamine, 1CH322NH; (b) carbonate ion, CO3 2-; (c) formate ion, CHO2 -.

Write the chemical equation and the Kb expression for the reaction of each of the following bases with water: (a) propylamine, C3H7NH2; (b) monohydrogen phosphate ion, HPO4 2-; (c) benzoate ion, C6H5CO2 -.

Calculate the molar concentration of OH- in a 0.075 M solution of ethylamine 1C2H5NH2; Kb = 6.4 * 10-4 2. Calculate the pH of this solution.

Calculate the molar concentration of OH- in a 0.724 M solution of hypobromite ion 1BrO-; Kb = 4.0 * 10-6 2. What is the pH of this solution?

Ephedrine, a central nervous system stimulant, is used in nasal sprays as a decongestant. This compound is a weak organic base: C10H15ON1aq2 + H2O1l2 C10H15ONH+1aq2 + OH-1aq2 A 0.035 M solution of ephedrine has a pH of 11.33. (a) What are the equilibrium concentrations of C10H15ON, C10H15ONH+, and OH-? (b) Calculate Kb for ephedrine.

Codeine 1C18H21NO32 is a weak organic base. A 5.0 * 10-3 M solution of codeine has a pH of 9.95. Calculate the value of Kb for this substance. What is the pKb for this base?

Although the acid-dissociation constant for phenol 1C6H5OH2 is listed in Appendix D, the base- dissociation constant for the phenolate ion 1C6H5O-2 is not. (a) Explain why it is not necessary to list both Ka for phenol and Kb for the phenolate ion. (b) Calculate Kb for the phenolate ion. (c) Is the phenolate ion a weaker or stronger base than ammonia?

Use the acid-dissociation constants in Table 16.3 to arrange these oxyanions from strongest base to weakest: SO4 2-, CO3 2-, SO3 2-, and PO4 3-.

(a) Given that Ka for acetic acid is 1.8 * 10-5 and that for hypochlorous acid is 3.0 * 10-8 , which is the stronger acid?

(b) Which is the stronger base, the acetate ion or the hypochlorite ion?

(c) Calculate Kb values for CH3COO- and ClO-.

a) Given that Kb for ammonia is 1.8 * 10-5 and that for hydroxylamine is 1.1 * 10-8 , which is the stronger base?

(b) Which is the stronger acid, the ammonium ion or the hydroxylammonium ion? (c) Calculate Ka values for NH4 + and H3NOH+.

Using data from Appendix D, calculate 3OH-4 and pH for each of the following solutions: (a) 0.10 M NaBrO, (b) 0.080 M NaHS, (c) a mixture that is 0.10 M in NaNO2 and 0.20 M in Ca1NO222.

Using data from Appendix D, calculate 3OH-4 and pH for each of the following solutions: (a) 0.105 M NaF, (b) 0.035 M Na2S, (c) a mixture that is 0.045 M in NaCH3COO and 0.055 M in Ba1CH3COO22.

A solution of sodium acetate 1NaCH3COO2 has a pH of 9.70. What is the molarity of the solution?

Pyridinium bromide 1C5H5NHBr2 is a strong electrolyte that dissociates completely into C5H5NH+ and Br -. A solution of pyridinium bromide has a pH of 2.95. What is the molarity of the solution?

Predict whether aqueous solutions of the following compounds are acidic, basic, or neutral: (a) NH4Br, (b) FeCl3, (c) Na2CO3, (d) KClO4, (e) NaHC2O4.

Predict whether aqueous solutions of the following substances are acidic, basic, or neutral: (a) AlCl3, (b) NaBr, (c) NaClO, (d) 3CH3NH34NO3, (e) Na2SO3.

An unknown salt is either NaF, NaCl, or NaOCl. When 0.050 mol of the salt is dissolved in water to form 0.500 L of solution, the pH of the solution is 8.08. What is the identity of the salt?

An unknown salt is either KBr, NH4Cl, KCN, or K2CO3. If a 0.100 M solution of the salt is neutral, what is the identity of the salt?

Explain the following observations: (a) HNO3 is a stronger acid than HNO2; (b) H2S is a stronger acid than H2O; (c) H2SO4 is a stronger acid than HSO4 -; (d) H2SO4 is a stronger acid than H2SeO4; (e) CCl3COOH is a stronger acid than CCl3COOH.

Explain the following observations: (a) HCl is a stronger acid than H2S; (b) H3PO4 is a stronger acid than H3AsO4; (c) HBrO3 is a stronger acid than HBrO2; (d) H2C2O4 is a stronger acid than HC2O4 -; (e) benzoic acid 1C6H5COOH2 is a stronger acid than phenol 1C6H5OH2.

Based on their compositions and structures and on conjugate acidbase relationships, select the stronger base in each of the following pairs: (a) BrO- or ClO-, (b) BrO- or BrO2 -, (c) HPO4 2- or H2PO4 -.

Based on their compositions and structures and on conjugate acidbase relationships, select the stronger base in each of the following pairs: (a) NO3 - or NO2 -, (b) PO4 3- or AsO4 3-, (c) HCO3 - or CO3 2-.

Indicate whether each of the following statements is true or false. For each statement that is false, correct the statement to make it true. (a) In general, the acidity of binary acids increases from left to right in a given row of the periodic table. (b) In a series of acids that have the same central atom, acid strength increases with the number of hydrogen atoms bonded to the central atom. (c) Hydrotelluric acid 1H2Te2 is a stronger acid than H2S because Te is more electronegative than S.

Indicate whether each of the following statements is true or false. For each statement that is false, correct the statement to make it true. (a) Acid strength in a series of HA molecules increases with increasing size of A. (b) For acids of the same general structure but differing electronegativities of the central atoms, acid strength decreases with increasing electronegativity of the central atom. (c) The strongest acid known is HF because fluorine is the most electronegative element.

If a substance is an Arrhenius base, is it necessarily a Brnsted Lowry base? Is it necessarily a Lewis base?

If a substance is a Lewis acid, is it necessarily a Brnsted Lowry acid? Is it necessarily an Arrhenius acid?

Identify the Lewis acid and Lewis base among the reactants in each of the following reactions: (a) Fe1ClO4231s2 + 6 H2O1l2 Fe1H2O26 3+1aq2 + 3 ClO4 -1aq2 (b) CN-1aq2 + H2O1l2 HCN1aq2 + OH-1aq2 (c) 1CH323N1g2 + BF31g2 1CH323NBF31s2 (d) HIO1lq2 + NH2 -1lq2 NH31lq2 + IO-1lq2 (lq denotes liquid ammonia as solvent)

Identify the Lewis acid and Lewis base in each of the following reactions: (a) HNO21aq2 + OH-1aq2 NO2 -1aq2 + H2O1l2 (b) FeBr31s2 + Br -1aq2 FeBr4 -1aq2 (c) Zn2+1aq2 + 4 NH31aq2 Zn1NH324 2+1aq2 (d) SO21g2 + H2O1l2 H2SO31aq2

Predict which member of each pair produces the more acidic aqueous solution: (a) K+ or Cu2+, (b) Fe 2+ or Fe 3+, (c) Al 3+ or Ga 3+.

Which member of each pair produces the more acidic aqueous solution: (a) ZnBr2 or CdCl2, (b) CuCl or Cu1NO322, (c) Ca1NO322 or NiBr2?

Indicate whether each of the following statements is correct or incorrect. (a) Every BrnstedLowry acid is also a Lewis acid. (b) Every Lewis acid is also a BrnstedLowry acid. (c) Conjugate acids of weak bases produce more acidic solutions than conjugate acids of strong bases. (d) K+ ion is acidic in water because it causes hydrating water molecules to become more acidic. (e) The percent ionization of a weak acid in water increases as the concentration of acid decreases.

A solution is made by adding 0.300 g Ca1OH221s2, 50.0 mL of 1.40 M HNO3, and enough water to make a final volume of 75.0 mL Assuming that all of the solid dissolves, what is the pH of the final solution?

The odor of fish is due primarily to amines, especially methylamine 1CH3NH22. Fish is often served with a wedge of lemon, which contains citric acid. The amine and the acid react forming a product with no odor, thereby making the less-than-fresh fish more appetizing. Using data from Appendix D, calculate the equilibrium constant for the reaction of citric acid with methylamine, if only the first proton of the citric acid 1Ka12 is important in the neutralization reaction.

For solutions of a weak acid, a graph of pH versus the logarithm of the initial acid concentration should be a straight line. What is the magnitude of the slope of that line?

Hemoglobin plays a part in a series of equilibria involving protonation-deprotonation and oxygenation- deoxygenation. The overall reaction is approximately as follows: HbH+1aq2 + O21aq2 HbO21aq2 + H+1aq2 where Hb stands for hemoglobin and HbO2 for oxyhemoglobin. (a) The concentration of O2 is higher in the lungs and lower in the tissues. What effect does high 3O24 have on the position of this equilibrium? (b) The normal pH of blood is 7.4. Is the blood acidic, basic, or neutral? (c) If the blood pH is lowered by the presence of large amounts of acidic metabolism products, a condition known as acidosis results. What effect does lowering blood pH have on the ability of hemoglobin to transport O2?

Calculate the pH of a solution made by adding 2.50 g of lithium oxide 1Li2O2 to enough water to make 1.500 L of solution

Benzoic acid 1C6H5COOH2 and aniline 1C6H5NH22 are both derivatives of benzene. Benzoic acid is an acid with Ka = 6.3 * 10-5 and aniline is a base with Ka = 4.3 * 10-10 . H H N O OH C Benzoic acid Aniline (a) What are the conjugate base of benzoic acid and the conjugate acid of aniline? (b) Anilinium chloride 1C6H5NH3Cl2 is a strong electrolyte that dissociates into anilinium ions 1C6H5NH3 +2 and chloride ions. Which will be more acidic, a 0.10 M solution of benzoic acid or a 0.10 M solution of anilinium chloride? (c) What is the value of the equilibrium constant for the following equilibrium? C6H5COOH1aq2 + C6H5NH21aq2 C6H5COO-1aq2 + C6H5NH3 +1aq2

What is the pH of a solution that is 2.5 * 10-9 M in NaOH? Does your answer make sense? What assumption do we normally make that is not valid in this case?

Oxalic acid 1H2C2O42 is a diprotic acid. By using data in Appendix D as needed, determine whether each of the following statements is true: (a) H2C2O4 can serve as both a Brnsted Lowry acid and a BrnstedLowry base. (b) C2O4 2- is the conjugate base of HC2O4 -. (c) An aqueous solution of the strong electrolyte KHC2O4 will have pH 6 7.

Succinic acid 1H2C4H6O42, which we will denote H2Suc, is a biologically relevant diprotic acid with the structure shown below. It is closely related to tartaric acid and malic acid (Figure 16.1). At 25 C, the acid-dissociation constants for succinic acid are Ka1 = 6.9 * 10-5 and Ka2 = 2.5 * 10-6 . (a) Determine the pH of a 0.32 M solution of H2Suc at 25 C, assuming that only the first dissociation is relevant. (b) Determine the molar concentration of Suc2 - in the solution in part (a). (c) Is the assumption you made in part (a) justified by the result from part (b)? (d) Will a solution of the salt NaHSuc be acidic, neutral, or basic? OH O C C C C O OH H H H H

Butyric acid is responsible for the foul smell of rancid butter. The pKa of butyric acid is 4.84. (a) Calculate the pKb for the butyrate ion. (b) Calculate the pH of a 0.050 M solution of butyric acid. (c) Calculate the pH of a 0.050 M solution of sodium butyrate.

Arrange the following 0.10 M solutions in order of increasing acidity (decreasing pH): (i) NH4NO3, (ii) NaNO3, (iii) CH3COONH4, (iv) NaF, (v) CH3COONa.

A 0.25 M solution of a salt NaA has pH = 9.29. What is the value of Ka for the parent acid HA?

The following observations are made about a diprotic acid H2A: (i) A 0.10 M solution of H2A has pH = 3.30. (ii) A 0.10 M solution of the salt NaHA is acidic. Which of the following could be the value of pKa2 for H2A: (i) 3.22, (ii) 5.30, (iii) 7.47, or (iv) 9.82?

Many moderately large organic molecules containing basic nitrogen atoms are not very soluble in water as neutral molecules, but they are frequently much more soluble as their acid salts. Assuming that pH in the stomach is 2.5, indicate whether each of the following compounds would be present in the stomach as the neutral base or in the protonated form: nicotine, Kb = 7 * 10-7 ; caffeine, Kb = 4 * 10-14 ; strychnine, Kb = 1 * 10-6 ; quinine, Kb = 1.1 * 10-6 .

The amino acid glycine 1H2NCH2COOH2 can participate in the following equilibria in water: H2NCH2COOH + H2O H2NCH2COO- + H3O+ Ka = 4.3 * 10-3 H2NC + H2COOH + H2O H3NCH2COOH + OH- Kb = 6.0 * 10-5 (a) Use the values of Ka and Kb to estimate the equilibrium constant for the intramolecular proton transfer to form a zwitterion: H2NCH2COOH +H3NCH2COO (b) What is the pH of a 0.050 M aqueous solution of glycine? (c) What would be the predominant form of glycine in a solution with pH 13? With pH 1?

The structural formula for acetic acid is shown in Table 16.2. Replacing hydrogen atoms on the carbon with chlorine atoms causes an increase in acidity, as follows: Acid Formula Ka125 C2 Acetic CH3COOH 1.8 * 10-5 Chloroacetic CH2ClCOOH 1.4 * 10-3 Dichloroacetic CHCl2COOH 3.3 * 10-2 Trichloroacetic CCl3COOH 2 * 10-1 Using Lewis structures as the basis of your discussion, explain the observed trend in acidities in the series. Calculate the pH of a 0.010 M solution of each acid.

Calculate the number of H+1aq2 ions in 1.0 mL of pure water at 25 C.

How many milliliters of concentrated hydrochloric acid solution (36.0% HCl by mass, density = 1.18 g>mL) are required to produce 10.0 L of a solution that has a pH of 2.05?

The volume of an adults stomach ranges from about 50 mL when empty to 1 L when full. If the stomach volume is 400 mL and its contents have a pH of 2, how many moles of H+ does the stomach contain? Assuming that all the H+ comes from HCl, how many grams of sodium hydrogen carbonate will totally neutralize the stomach acid?

Atmospheric CO2 levels have risen by nearly 20% over the past 40 years from 315 ppm to 380 ppm. (a) Given that the average pH of clean, unpolluted rain today is 5.4, determine the pH of unpolluted rain 40 years ago. Assume that carbonic acid 1H2CO32 formed by the reaction of CO2 and water is the only factor influencing pH. CO21g2 + H2O1l2 H2CO31aq2 (b) What volume of CO2 at 25 C and 1.0 atm is dissolved in a 20.0-L bucket of todays rainwater?

At 50 C, the ion-product constant for H2O has the value Kw = 5.48 * 10-14 . (a) What is the pH of pure water at 50 C? (b) Based on the change in Kw with temperature, predict whether H is positive, negative, or zero for the autoionization reaction of water: 2 H2O1l2 H3O+1aq2 + OH-1aq2

In many reactions the addition of AlCl3 produces the same effect as the addition of H+. (a) Draw a Lewis structure for AlCl3 in which no atoms carry formal charges, and determine its structure using the VSEPR method. (b) What characteristic is notable about the structure in part (a) that helps us understand the acidic character of AlCl3? (c) Predict the result of the reaction between AlCl3 and NH3 in a solvent that does not participate as a reactant. (d) Which acidbase theory is most suitable for discussing the similarities between AlCl3 and H+?

What is the boiling point of a 0.10 M solution of NaHSO4 if the solution has a density of 1.002 g>mL?

Use average bond enthalpies from Table 8.4 to estimate the enthalpies of the following gas-phase reactions: Reaction 1: HF1g2 + H2O1g2 F-1g2 + H3O+1g2 Reaction 2: HCl1g2 + H2O1g2 Cl -1g2 + H3O+1g2 Are both reactions exothermic? How do these values relate to the different strengths of hydrofluoric and hydrochloric acid?

Cocaine is a weak organic base whose molecular formula is C17H21NO4. An aqueous solution of cocaine was found to have a pH of 8.53 and an osmotic pressure of 52.7 torr at 15 C. Calculate Kb for cocaine.

The iodate ion is reduced by sulfite according to the following reaction: IO3 -1aq2 + 3SO3 2-1aq2 I -1aq2 + 3 SO4 2-1aq2 The rate of this reaction is found to be first order in IO3 -, first order in SO3 2-, and first order in H+. (a) Write the rate law for the reaction. (b) By what factor will the rate of the reaction change if the pH is lowered from 5.00 to 3.50? Does the reaction proceed more quickly or more slowly at the lower pH? (c) By using the concepts discussed in Section 14.6, explain how the reaction can be pH-dependent even though H+ does not appear in the overall reaction

(a) Using dissociation constants from Appendix D, determine the value for the equilibrium constant for each of the following reactions. (i) HCO3 -1aq2 + OH-1aq2 CO3 2-1aq2 + H2O1l2 (ii) NH4 +1aq2 + CO3 2-1aq2 NH31aq2 + HCO3 -1aq2

(b) We usually use single arrows for reactions when the forward reaction is appreciable (K much greater than 1) or when products escape from the system, so that equilibrium is never established. If we follow this convention, which of these equilibria might be written with a single arrow?

Problem 1DE Your professor gives you a bottle that contains a clear liquid. You are told that the liquid is a pure substance that is volatile, soluble in water, and might be an acid or a base. Design experiments to elucidate the following about this unknown sample, (a) Determine whether the substance in the sample is an acid or a base, (b) Suppose the substance is an acid. How would you determine whether it is a strong acid or a weak acid? (c) If the substance is a weak acid, how would you determine the value of Ka for the substance? (d) Suppose the substance were a weak acid and that you are also given a solution of NaOH(ag) of known molarity. What procedure would you use to isolate a pure sample of the sodium sal: of the substance? (e) Now suppose that the substance were a base rather than an acid. How would you adjust the procedures in parts (b) and (c) to determine if the substance were a strong or weak base. and. if weak, the value of Kb?

(a) Identify the Brønsted–Lowry acid and base in the reaction (b) Identify the Lewis acid and base in the reaction. [Sections 16.2 and 16.11]

The following diagrams represent aqueous solutions of two monoprotic acids, HA (A = X or Y). The water molecules have been omitted for clarity. (a) Which is the stronger acid, HX or HY? (b) Which is the stronger base, \(X^{-}\) or \(Y^{-}\) ? (c) If you mix equal concentrations of HX and NaY, will the equilibrium \(H X(a q)+Y^{-}(a q) \leftrightarrow H Y(a q)+X^{-}(a q)\) lie mostly to the right \(\left(K_{c}>1\right)\) or to the left \(\left(K_{c}<1\right)\)? [Section 16.2] Equation transcription: Text transcription: X^{-} Y^{-} H X(a q)+Y^{-}(a q) leftrightarrow H Y(a q)+X^{-}(a q) (K_{c}>1) (K_{c}<1)

The indicator methyl orange has been added to both of the following solutions. Based on the colors, classify each statement as true or false: (a) The pH of solution A is definitely less than 7.00. (b) The pH of solution B is definitely greater than 7.00. (c) The pH of solution B is greater than that of solution A. [Section 16.4]

The probe of the pH meter shown here is sitting in a beaker that contains a clear liquid. (a) You are told the liquid is pure water, a solution of \(H C I(a q)\), or a solution of \(\mathrm{KOH}(a q)\). Which one is it? (b) If the liquid is one of the solutions, what is its molarity? (c) Why is the temperature given on the pH meter? [Sections 16.4 and 16.5] Equation transcription: Text transcription: H C I(a q) {KOH}(a q)

The following diagrams represent aqueous solutions of three acids, HX, HY, and HZ. The water molecules have been omitted for clarity, and the hydrated proton is represented as H+ rather than \(\mathrm{H}_{3} \mathrm{O}^{+}\). (a) Which of the acids is a strong acid? Explain. (b) Which acid would have the smallest acid-dissociation constant, \(K_{a}\)? (c) Which solution would have the highest pH? [Sections 16.5 and 16.6] Equation transcription: Text transcription: {H}{3}{O}^{+} K{a}

The graph given below shows \(\left[H^{+}\right]\) vs. concentration for an aqueous solution of an unknown substance. (a) Is the substance a strong acid, a weak acid, a strong base, or a weak base? (b) Based on your answer to (a), can you determine the value of the pH of the solution when the concentration is 0.18 M? (c) Would the line go exactly through the origin of the plot? [Sections 16.5 and 16.6] Equation transcription: Text transcription: [H^{+}]

(a) Which of these three lines represents the effect of concentration on the percent ionization of a weak acid? (b) Explain in qualitative terms why the curve you chose has the shape it does. [Section 16.6]

Each of the three molecules shown here contains an OH group, but one molecule acts as a base, one as an acid, and the third is neither acid nor base. (a) Which one acts as a base? Why does only this molecule act as a base? (b) Which one acts as an acid? (c) Why is the remaining molecule neither acidic nor basic? [Sections 16.6 and 16.7]

Phenylephrine, an organic substance with molecular formula \(\mathrm{C}_{9} \mathrm{H}_{13} \mathrm{NO}_{2}\), is used as a nasal decongenstant in over-the-counter medications. The molecular structure of phenylephrine is shown below using the usual shortcut organic nomenclature. (a) Would you expect a solution of phenylephrine to be acidic, neutral, or basic? (b) One of the active ingredients in Alka-Seltzer PLUS® cold medication is “phenylephrine hydrochloride.” How does this ingredient differ from the structure shown below? (c) Would you expect a solution of phenylephrine hydrochloride to be acidic, neutral, or basic? [Sections 16.8 and 16.9] Equation transcription: Text transcription: {C}_{9}{H}_{13}{NO}_{2}

Which of the following diagrams best represents an aqueous solution of NaF? (For clarity, the water molecules are not shown.) Will this solution be acidic, neutral, or basic? [Section 16.9]

Consider the molecular models shown here, where X represents a halogen atom. (a) If X is the same atom in both molecules, which molecule will be more acidic? (b) Does the acidity of each molecule increase or decrease as the electronegativity of the atom X increases? [Section 16.10]

(a) The following diagram represents the reaction of \(P C I_{4}^{+}\) with Cl?. Draw the Lewis structures for the reactants and products, and identify the Lewis acid and the Lewis base in the reaction. (b) The following reaction represents a hydrated cation losing a proton. How does the equilibrium constant for the reaction change as the charge of the cation increases? [Sections 16.9 and 16.11] Equation transcription: Text transcription: P C I{4}^{+}

Problem 13E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) (a) What is the difference between the Arrhenius and the Bronsted-LowTy definitions of an acid? (b) NH3(g) and HCI(g) react to form the ionic solid NH4CI(s). Which substance is the Bronsted-Lowry acid in this reaction? Which is the Bronsted-Lowry base?

Problem 14E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) (a) What is the difference between the Arrhenius and the Bronsted-Lowiy definitions of a base? (b) Can a substance behave as an Arrhenius base if it does not contain an OH group? Explain. Step-by-step solution

Problem 15E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) (a) Give the conjugate base of the following Bronsted-Lowry acids:(i) HI03. (ii) NH4+. (b) Give the conjugate acid of the following Bronsted-Lowry bases: (i) 02-, (ii) H2P04-.

Problem 16E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) (a) Give the conjugate base of the following Brnsted-Lowry acids: (i) HCOOH, (ii) HPO42- (b) Give the conjugate acid of the following Brnsted-Lowry bases: (i) SO42-, (ii) CH3NH2.

Problem 18E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) Designate the Bronsted-Lowry acid and the Bronsted-Lowry base on the left side of each equation, and also designate the conjugate acid and conjugate base of each on the right side. (a) HBrO(aq) + H2O H3O+(aq) + BrO-(aq) (b) HSO4-(aq) + HCO3-(aq) SO42 - (aq) + H2CO3(aq) (c) HSO3-(aq) + H3O+(aq)H2SO3(aq) + H2O(l)

Problem 17E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) Designate the Bronsted-Lowry acid and the Bronsted-Lowry base on the left side of each of the following equations, and also designate the conjugate acid and conjugate base of each on the right side: (a) NH4+(aq) + CN-(aq) (b) (CH3)3N(aq) + H2O(l) (c) HCOOH(aq) + PO43-(aq)HCOO-(aq) + HPO42-(aq)

Problem 19E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) (a) The hydrogen sutfite ion (HS03-) is amphiprotic. Write a balanced chemical equation showing how it acts as an acid toward water and another equation showing how it acts as a base toward water, (b) What is the conjugate acid of HS03 -? What is its conjugate base?

Problem 20E Arrhenius and Bronsted-Lowry Acids and Bases (Sections) (a) Write an equation for the reaction in which H2C6H705 ~{aq) acts as a base in H20(I). (b) Write an equation for the reaction in which H2C6H705-(ag) acts as an acid in H20(I). (c) What is the conjugate acid of H2C6H705-(ag>)? What is its conjugate base?

Problem 21E Arrhenius and Br0nsted-Lowry Acids and Bases (Sections) Label each of the following as being a strong base, a weak base, or a species with negligible basicity. In each case write the formula of its conjugate acid, and indicate whether the conjugate acid is a strong acid, a weak acid, or a species with negligible acidity: (a) CH3COO-, (b) HC03-, (c) 02-, (d) CI-, (e) NH3.

Problem 22E Arrhenius and Br0nsted-Lowry Acids and Bases (Sections) Label each of the following as being a strong acid, a weak acid, or a species with negligible acidity. In each case write the formula of its conjugate base, and indicate whether the conjugate base is a strong base, a weak base, or a species with negligible basicity: (a) HCOOH, (b) H2, (c) CH4, (d) HF, (e) NH4+.

Problem 23E Arrhenius and Br0nsted-Lowry Acids and Bases (Sections) (a) Which of the following is the stronger Br0nsted-Lowry acid, HBrO or HBr? (b) Which is the stronger Br0nsted-Lowry base, F- or CI-?

Problem 24E Arrhenius and Br0nsted-Lowry Acids and Bases (Sections) (a) Which of the following is the stronger Br0nsted-Lowry acid, HClO3 or HClO2? (b) Which is the stronger Br0nsted-Lowry base, HS- or HS04-?

Problem 25E Arrhenius and Br0nsted-Lowry Acids and Bases (Sections) Predict the products of the following acid-base reactions, and predict whether the equilibrium lies to the left or to the right of the equation: (a) O2-(aq) + H2O(l) ? (b) CH3COOH(aq) + HS-(aq) ? (c) NO2-(aq) + H2O(l) ?

Problem 26E Arrhenius and Br0nsted-Lowry Acids and Bases (Sections) Predict the products of the following acid-base reactions, and predict whether the equilibrium lies to the left or to the right of the equation: (a) NH4 + (aq) + OH-(aq) ? (b) CH3COO-(aq) + H3O+(aq)? (c) HCO3-(aq) + F-(aq) ?

Problem 27E Autoionization of Water (Section) If a neutral solution of water, with pH = 7 00. is cooled to 10 °C. the pH rises to 7.27. Which of the following three statements is correct for the cooled water (i) (H+) > [OH-], (ii) [H+]= [OH-], or (iii) [H+]<[OH-]?

Problem 28E Autoionization of Water (Section) (a) Write a chemical equation that illustrates the autoionization of water, (b) Write the expression for the ion-product constant for water, Kw. (c) If a solution is described as basic, which of the following is true: (i) [H+]>[OH-], (ii) [H+] = [OH-], or (iii) [H+]<[OH-]?

Problem 29E Autoionization of Water (Section) Calculate [H+] for each of the following solutions, and indicate whether the solution is acidic, basic, or neutral: (a) [OH-] = 0.00045 M; (b) [OH-] = 8.8 x 10-9 M; a solution in which [OH-] is 100 times greater than [H+]

Problem 30E Autoionization of Water (Section) Calculate [OH-] for each of the following solutions, and indicate whether the solution is acidic, basic, or neutral: (a) [H+] = 0.0505 M; (b) [H+] = 2.5 x 10-10 M; (c) a solution in which [H+] is 1000 times greater than [OH-].

At the freezing point of water (0°C), \(K_{w}=1.2 \times 10^{15}\). Calculate \(\left[H^{+}\right]\) and \(\left[\mathrm{OH}^{-}\right]\) for a neutral solution at this temperature. Equation transcription: Text transcription: Text transcription: K{w}=1.2 times 10^{15} [H^{+}] [{OH}^{-}]

Problem 32E Autoionization of Water (Section) Deuterium oxide (D20, where D is deuterium, the hydrogen-2 isotope) has an ion-product constant, Kw, of 3.9 x 10-16 at 20 °C. Calculate [D+] and [OD-] for pure (neutral) D20 at this temperature.

Problem 34E The pH Scale (Section) Consider two solutions, solution A and solution B. [H+] in solution A is 250 times greater than that in solution B. What is the difference in the pH values of the two solutions?

Problem 33E The pH Scale (Section) By what factor does [H+] change for a pH change of (a) 2.00 units, (b) 0.50 units?

Complete the following table by calculating the missing entries and indicating whether the solution is acidic or basic.

Complete the following table by calculating the missing entries. In each case indicate whether the solution is acidic or basic.

The average pH of normal arterial blood is 7.40. At normal body temperature (37°C), \(K_{W}=2.4 \times 10^{-14}\). Calculate \(\left[H^{+}\right],\left[O H^{-}\right]\), and pOH for blood at this temperature. Equation transcription: Text transcription: K_{W}=2.4 \times 10^{-14} [H^{+}],[O H^{-}]

The pH Scale (Section) Carbon dioxide in the atmosphere dissolves in raindrops to produce carbonic acid , causing the pH of clean, unpolluted rain to range from about 5.2 to 5.6. What are the ranges of and in the raindrops?

The pH Scale (Section) Addition of the indicator methyl orange to an unknown solution leads to a yellow color. The addition of bromothymol blue to the same solution also leads to a yellow color, (a) Is the solution acidic, neutral, or basic? (b) What is the range (in whole numbers) of possible pH values for the solution? (c) Is there another indicator you could use to narrow the range of possible pH values for the solution?

The pH Scale (Section) Addition of phenolphthalein to an unknown colorless solution does not cause a color change. The addition of bromothymol blue to the same solution leads to a yellow color, (a) Is the solution acidic, neutral, or basic? (b) Which of the following can you establish about the solution: (i) A minimum pH, (ii) A maximum pH, or (iii) A specific range of pH values? (c) What other indicator or indicators would you want to use to determine the pH of the solution more precisely?

Strong Acids and Bases (Section) Is each of the following statements true or false? (a) All strong acids contain one or more H atoms, (b) A strong acid is a strong electrolyte, (c) A 1.0-M solution of a strong acid will have pH = 1.0.

Strong Acids and Bases (Section) Determine whether each of the following is true or false: (a) All strong bases are salts of the hydroxide ion. (b) The addition of a strong base to water produces a solution of pH > 7.0. (c) Because is not very soluble, it cannot be a strong base.

Strong Acids and Bases (Section) Calculate the pH of each of the following strong acid solutions: (a) , (b) in 575 rnL of solution, (c) 5.00 rnL of 0.250 M diluted to 50.0 rnL, (d) a solution formed by mixing 10.0 rnL of 0.100 M HBr with 20.0 rnL of 0.200 M HCI.

Calculations for a Weak Acid-Strong Base Titration Calculate the pH of the solution formed when 45.0 mL of 0.100 M NaOH is added to 50.0 mL of . If you think carefully about what happens during the course of a weak acid-strong base titration, you can learn some very interesting things. For example, let's look back at Figure and pretend you did not know that acetic acid was the acid being titrated Ybu can figure out the pKa of a weak acid just by thinking about the definition of Ka and looking at the right place on the titration curve! Which of the following choices is the best way to do this? Figure Titration of a weak acid with a strong base. The pH curve for titration of 50.0 mL of a 0.100 M solution of acetic acid with a 0.100 M solution of NaOH1(aq). For clarity, water molecules have been omitted from the molecular art. If the acetic acid being titrated here were replaced by hydrochloric acid, would the amount of base needed to reach the equivalence point change? Would the pH at the equivalence point change? (a) At the equivalence point. pH = pKa., (b) Hallway to the equivalence point, pH = pKa., (c) Before any base is added, pH = pKa., (d) At the top of the graph with excess base added. pH = p Ka.

Problem 45E Strong Acids and Bases (Section) Calculate [OH-] and pH for (a) 1.5 x 10-3M Sr(OH)2, (b) 2.250 g of LiOH in 250.0 rnL of solution, (c) 1.00 rnL of 0.175 M NaOH diluted to 2.00 L, (d) a solution formed by adding 5.00 rnL of 0.105 M KOH to 15.0 rnL of 9.5 x 10-2 M Ca(OH)2.

Why is pH at the equivalence point larger than 7 when you titrate a weak acid with a strong base? (a) There is excess strong base at the equivalence point., (b) There is excess weak acid at the equivalence point.. (c) The conjugate base that is formed at the equivalence point is a strong base.. (d) The conjugate base that is formed at the equivalence point reacts with water.. (e) This statement is false: the pH is always 7 at an equivalence point in a pH titration.

Problem 47E Strong Acids and Bases (Section) Calculate the concentration of an aqueous solution of NaOH that has a pH of 11.50.

Strong Acids and Bases (Section) Calculate the concentration of an aqueous solution of that has a pH of 10.05.

Writing Solubility-Product (Ksp) Expressions Write the expression for the solubility-product constant for , and look up the corresponding Ksp value in Appendix D. Give the solubility-product-constant expressions and Ksp values (from Appendix D) for (a) barium carbonate and, (b) silver sulfate.

Problem 50E Weak Acids (Section) Write the chemical equation and the Ka expression for the acid dissociation of each of the following acids in aqueous solution. First show the reaction with H+{aq) as a product and then with the hydroniurn ion: (a) C6H5COOH, (b) HC03-.

Weak Acids (Section) Lactic acid has one acidic hydrogen. A 0.10 M solution of lactic acid has a pH of 2.44. Calculate Ka.

Problem 52E Weak Acids (Section) Phenylacetic acid (C6H5CH2COOH) is one of the substances that accumulates in the blood of people with phenylketonuria, an inherited disorder that can cause mental retardation or even death. A 0.085 M solution of C6H5CH2COOH has a pH of 2.68. Calculate the Ka value for this acid

A 0.100 M solution of chloroacetic acid is 11.0% ionized. Using this information, calculate , , and for chloroacetic acid.

A 0.100 M solution of bromoacetic acid \(\left[B r C H_{2} C O O H\right]\) is 13.2% ionized. Calculate \(\left[H^{+}\right]\), \(\left[\mathrm{BrCH}_{2} \mathrm{COO}^{-}\right]\), \(\left[B r C H_{2} C O O H\right]\) and \(K_{a}\) for bromoacetic acid. Equation transcription: Text transcription: [B r C H_{2} C O O H] [H^{+}] [{BrCH}_{2}{COO}^{-}] K_{a}

Weak Acids (Section) A particular sample of vinegar has a pH of 2.90. If acetic acid is the only acid that vinegar contains , calculate the concentration of acetic acid in the vinegar.

Problem 56E Weak Acids (Section) If a solution of HF (Ka = 6.8 x 10-4) has a pH of 3.65, calculate the concentration of hydrofluoric acid.

Weak Acids (Section) The acid-dissociation constant for chlorous acid is . Calculate the concentrations of and at equilibrium if the initial concentration of is 0.0125 M.

Weak Acids (Section) The acid-dissociation constant for benzoic acid is . Calculate the equilibrium concentrations of , and in the solution if the initial concentration of is 0.050 M.

Problem 59E Weak Acids (Section) Calculate the pH of each of the following solutions (Ka and Kb values are given in Appendix D): (a) 0.095 M propionic acid (C2H5COOH), (b) 0.100 M hydrogen chromate ion (HCr04-), (c) 0.120 M pyridine (C5H5N).

Problem 60E Weak Acids (Section) Determine the pH of each of the following solutions ( Ka and Kb’ values are given in Appendix D): (a) 0.095 M hypochlorous acid, (b) 0.0085 M hydrazine, (c) 0.165 M hydroxylamine.

Saccharin, a sugar substitute, is a weak acid with \(p K_{a}=2.32\) at 25°C. It ionizes in aqueous solution as follows: \(H N C_{7} H_{4} S O_{3}(a q) \leftrightarrow H^{+}(a q)+N C_{7} H_{4} S O_{3}^{-}(a q)\) What is the pH of a 0.10 M solution of this substance? Equation transcription: Text transcription: p K{a}=2.32 H N C{7} H{4} S O{3}(a q) leftrightarrow H^{+}(a q)+N C{7} H_{4} S O{3}^{-}(a q)

Problem 62E Weak Acids (Section) The active ingredient in aspirin is acetylsalicylic acid (HC9H704), a rnonoprotic acid with Ka = 3.3 x 10-4 at 25 °C. What is the pH of a solution obtained by dissolving two extra-strength aspirin tablets, containing 500 mg of acetylsalicylic acid each, in 250 rnl_ of water?3

Problem 63E Weak Acids (Section) Calculate the percent ionization of hydrazoic acid (HN3) in solutions of each of the following concentrations (Ka is given in Appendix D): (a) 0.400 W, (b) 0.100 W. (c) 0.0400 M.

Problem 64E Weak Acids (Section) Calculate the percent ionization of propionic acid (C2H5COOH) in solutions of each of the following concentrations (Ka is given in Appendix D): (a) 0.250 M, (b) 0.0800 M, (c) 0.0200 M.

Citric acid, which is present in citrus fruits, is a triprotic acid (Table 16.3). (a) Calculate the pH of a 0.040 M solution of citric acid. (b) Did you have to make any approximations or assumptions in completing your calculations? (c) Is the concentration of citrate ion \(\left(C_{6} H_{5} O_{7}^{3-}\right)\) equal to, less than, or greater than the \(H^{+}\) ion concentration? Equation transcription: Text transcription: (C{6} H{5} O{7}^{3-}) H^{+}

Tartaric acid is found in many fruits, including grapes, and is partially responsible for the dry texture of certain wines. Calculate the pH and the tartrate ion \(\left(C_{4} H_{4} O_{6}^{2-}\right)\) concentration for a 0.250 M solution of tartaric acid, for which the acid-dissociation constants are listed in Table 16.3. Did you have to make any approximations or assumptions in your calculation? Equation transcription: Text transcription: (C{4} H{4} O{6}^{2-})

Problem 67E Weak Bases (Section) Consider the base hydroxylamine, NH20H. (a) What is the conjugate acid of hydroxylamine? (b) When it acts as a base, which atom in hydroxylamine accepts a proton? (c) There are two atoms in hydroxylamine that have nonbonding electron pairs that could act as proton acceptors. Use Lewis structures and formal charges (Section) to rationalize why one of these two atoms is a much better proton acceptor than the other..

Problem 68E Weak Bases (Section) The hypochlorite ion, CIO-, acts as a weak base, (a) Is CIO- a stronger or weaker base than hydroxylamine? (b) When ClO acts as a base, which atom, Cl or O, acts as the proton acceptor? (c) Can you use formal charges to rationalize your answer to part (b)?

Write the chemical equation and the \(K_{b}\) expression for the reaction of each of the following bases with water: (a) dimethylamine, \(\left(\mathrm{CH}_{3}\right) \mathrm{NH}\); (b) carbonate ion, \(\mathrm{CO}_{3}^{2-}\) (c) formate ion, \(\mathrm{CHO}_{2}^{-}\) Equation transcription: Text transcription: K{b} {CO}{3}^{2-} {CHO}{2}^{-}

Problem 70E Weak Bases (Section) Write the chemical equation and the Kb expression for the reaction of each of the following bases with water: (a) propylamine, C3H7NH2; (b) monohydrogen phosphate ion, HP042-; (c) benzoate ion, C6H5C02-

Problem 71E Weak Bases (Section) Calculate the molar concentration of OH- in a 0.075 M solution of ethylamine (C2H5NH2; Kb 6.4 x 10-4). Calculate the pH of this solution.

Problem 73E Weak Bases (Section) Ephedrine, a central nervous system stimulant, is used in nasal sprays as a decongestant. This compound is a weak organic Base: C10H15ON(aq) + H2O(l) ? C10H15ONH+(aq) + OH-(aq) A 0.035 M solution of ephedrine has a pH of 11.33. (a) What are the equilibrium concentrations of C10H15OM, C10H15ON H+, and OH-? (b) Calculate Kb for ephedrine.

Problem 72E Weak Bases (Section) Calculate the molar concentration of OH- in a 0.724 M solution of hypobromite ion (BrO-; Kb = 4.0 x 10-6). What is the pH of this solution?

Problem 74E Weak Bases (Section) Codeine (C18H21N03) is a weak organic base. A 5.0 x 10-3M solution of codeine has a pH of 9.95. Calculate the value of Kb for this substance. What is the pKb for this base?

Problem 75E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) Although the acid-dissociation constant for phenol (C6H50H) is listed in Appendix D, the base-dissociation constant for the phenolate ion (C6H50-) is not. (a) Explain why it is not necessary to list both Ka for phenol and Kb for the phenolate ion. (b) Calculate Kb for the phenolate ion. (c) Is the phenolate ion a weaker or stronger base than ammonia?

Use the acid-dissociation constants in Table 16.3 to arrange these oxyanions from strongest base to weakest: \(S O_{4}^{2-}\), \(\mathrm{CO}_{3}^{2-}\), \(\mathrm{SO}_{3}^{2-}\), and \(P O_{4}^{3-}\). Equation transcription: Text transcription: S O_{4}^{2-} {CO}_{3}^{2-} {SO}_{3}^{2-} P O_{4}^{3-}

Problem 78E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) (a) Given that Kb for ammonia is 1.8 X 10-5 and that for hydroxylamine is 1.1 X 10-8, which is the stronger base? (b) Which is the stronger acid, the arnrnoniurn ion or the hydroxylammonium ion? (c) Calculate Ka values for NH4 + and H3NOH+.

Problem 77E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) (a) Given that Ka for acetic acid is 1.8 x 10-5 and that for hypochlorous acid is 3.0 x 10-8, which is the stronger acid? (b) Which is the stronger base, the acetate ion or the hypochlorite ion? (c) Calculate Kb values for CH3COO- and CIO-.

Problem 80E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) Using data from Appendix D, calculate [OH-] and pH for each of the following solutions: (a) 0.105 M NaF, (b) 0.035 M Na2S, (c) a mixture that is 0.045 M in NaCH3COO and 0.055 M in Ba(CH3COO)2.

Problem 81E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) A solution of sodium acetate (NaCH3COO) has a pH of 9.70. What is the molarity of the solution?

Problem 82E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) Pyridinium bromide (C5H5NHBr) is a strong electrolyte that dissociates completely into C5H5NH+ and Br-. A solution of pyridinium bromide has a pH of 2.95. What is the molarity of the solution?

Problem 83E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) Predict whether aqueous solutions of the following compounds are acidic, basic, or neutral: (a) NH4Br, (b) FeCL3, (c) Na2C03, (d) KCI04, (e) NaHC 204.

Problem 84E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) Predict whether aqueous solutions of the following substances are acidic, basic, or neutral: (a) AICI3, (b) NaBr, (c) NaCIO, (d) [CH3NH3]N03, (e) Na2S03.

Problem 85E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) An unknown salt is either NaF, NaCI, or NaOCI. When 0.050 mol of the salt is dissolved in water to form 0.500 L of solution, the pH of the solution is 8.08. What is the identity of the salt?

Problem 86E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) An unknown salt is either KBr, NH4Cl, KCN, or K2CO3. If a 0.100 M solution of the salt is neutral, what is the identity of the salt?

Problem 87E Acid-Base Character and Chemical Structure (Section) Explain the following observations: (a) HN03 is a stronger acid than HN02; (b) H2S is a stronger acid than H20; (c) H2S04 is a stronger acid than HS04-; (d) H2S04 is a stronger acid than H2Se04; (e) CCI3COOH is a stronger acid than CCI3COOH.

Problem 88E Acid-Base Character and Chemical Structure (Section) Explain the following observations: (a) HCI is a stronger acid than H2S; (b) H3P04 is a stronger acid than H3As04; (c) HE>r03 is a stronger acid than HE>r02; (d) H2C204 is a stronger acid than HC204 (e) benzoic acid (C6H5COOH) is a stronger acid than phenol (C6H50H).

Based on their compositions and structures and on conjugate acid–base relationships, select the stronger base in each of the following pairs: (a) \(\mathrm{BrO}^{-}\) or \(\mathrm{CIO}^{-}\), (b) \(\mathrm{BrO}^{-}\) or \(\mathrm{BrO}_{2}^{-}\), (c) \(\mathrm{HPO}_{4}^{2-}\) or \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\). Equation transcription: Text transcription: {BrO}^{-} {CIO}^{-} {BrO}_{2}^{-} {HPO}_{4}^{2-} {H}_{2}{PO}_{4}^{-}

Problem 90E Acid-Base Character and Chemical Structure (Section) Based on their compositions and structures and on conjugate acid-base relationships, select the stronger base in each of the following pairs: (a) N03- or N02-, (b) P04 3- or As043-, (c) HC03-or C032-.

Problem 91E Acid-Base Character and Chemical Structure (Section) Indicate whether each of the following statements is true or false. For each statement that is false, correct the statement to make it true, (a) In general, the acidity of binary acids increases from left to right in a given row of the periodic table, (b) In a series of acids that have the same central atom, acid strength increases with the number of hydrogen atoms bonded to the central atom, (c) Hydrotelluric acid (H2Te) is a stronger acid than H2S because Te is more electronegative than S.

Problem 92E Acid-Base Character and Chemical Structure (Section) Indicate whether each of the following statements is true or false. For each statement that is false, correct the statement to make it true, (a) Acid strength in a series of H—A molecules increases with increasing size of A. (b) For acids of the same general structure but differing electronegativities of the central atoms, acid strength decreases with increasing electronegativity of the central atom, (c) The strongest acid known is HF because fluorine is the most electronegative element.

Problem 93E Lewis Acids and Bases (Section) If a substance is an Arrhenius base, is it necessarily a Bronsted-Lowry base? Is it necessarily a Lewis base?

Problem 94E If a substance is a Lewis acid, is it necessarily a Bronsted-Lowry acid? Is it necessarily an Arrhenius acid?

Problem 95E Lewis Acids and Bases (Section) Identify the Lewis acid and Lewis base among the reactants in each of the following reactions: (a) Fe(ClO4)3(s) + 6 H2O(l) ? Fe(H2O)63+(aq) + 3 ClO4-(aq) (b) CN-(aq) + H2O(l) ? HCN(aq) + OH-(aq) (c) (CH3)3N(g) + BF3(g) ? (CH3)3NBF3(s) (d) HlO(lq) + NH2-(lq) ? NH3(lq) + lO-(lq) (lq denotes liquid ammonia as solvent)

Identify the Lewis acid and Lewis base in each of the following reactions: (a) \(\mathrm{HNO}_{2}(a q)+\mathrm{OH}^{-}(a q) \leftrightarrow \mathrm{NO}_{2}^{-}(a q)+\mathrm{H}_{2} \mathrm{O}(I)\) (b) \(F e B r_{3}(s)+B r^{-}(a q) \leftrightarrow F e B r_{4}^{-}(a q)\) (c) \(Z n^{2+}(a q)+4 N H_{3}(a q) \leftrightarrow Z n\left(N H_{3}\right)_{4}^{2+}(a q)\) (d) \(\mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(I) \leftrightarrow \mathrm{H}_{2} \mathrm{SO}_{3}(a q)\) Equation transcription: Text transcription: {HNO}_{2}(a q)+{OH}^{-}(a q)leftrightarrow{NO}_{2}^{-}(a q)+{H}_{2}{O}(I) F e B r{3}(s)+B r^{-}(a q) leftrightarrow F e B r_{4}^{-}(a q) Z n^{2+}(a q)+4 N H_{3}(a q) leftrightarrow Z n(N H_{3})_{4}^{2+}(a q) {SO}_{2}(g)+{H}_{2}{O}(I) leftrightarrow{H}_{2}{SO}_{3}(a q)

Predict which member of each pair produces the more acidic aqueous solution: (a) \(K^{+}\) or \(C u^{2+}\), (b) \(\mathrm{Fe}^{2+}\) or \(\mathrm{Fe}^{3+}\), (c) \(A I^{3+}\) or \(G a^{3+}\). Equation transcription: Text transcription: K^{+} C u^{2+} {Fe}^{2+} {Fe}^{3+} A I^{3+} G a^{3+}

Problem 98AE Lewis Acids and Bases (Section) Which member of each pair produces the more acidic aqueous solution: (a) ZnBr2 or CdCI2, (b) CuCI or Cu(N03)2, (c) Ca(N03)2 or NiBr2?

Problem 99AE Indicate whether each of the following statements is correct or incorrect. (a) Every Bronsted-Lowry acid is also a Lewis acid. (b) Every Lewis acid is also a Bronsted-Lowry acid. (c) Conjugate acids of weak bases produce more acidic solutions than conjugate acids of strong bases. (d) K+ ion is acidic in water because it causes hydrating water molecules to become more acidic. (e) The percent ionization of a weak acid in water increases as the concentration of acid decreases.

Problem 100AE A solution is made by adding 0.300 g Ca(OH)2(s), 50.0 rnL of 1.40 M HN03, and enough water to make a final volume of 75.0 rnL Assuming that all of the solid dissolves, what is the pH of the final solution?

Problem 101AE The odor of fish is due primarily to amines, especially rnethylarnine (CH3NH2). Fish is often served with a wedge of lemon, which contains citric acid. The arnine and the acid react forming a product with no odor, thereby making the less-than-fresh fish more appetizing. Using data from Appendix D, calculate the equilibrium constant for the reaction of citric acid with rnethylarnine, if only the first proton of the citric acid (Ka1) is important in the neutralization reaction.

Problem 102AE For solutions of a weak acid, a graph of pH versus the logarithm of the initial acid concentration should be a straight line. What is the magnitude of the slope of that line?

Problem 103AE Hemoglobin plays a part in a series of equilibria involving protonation-deprotonation and oxygenation-deoxygenation. The overall reaction is approximately as follows HbH + (aq) + O2(aq) ? HbO2(aq) + H + (aq) where Hb stands for hemoglobin and Hb02 for oxyhemoglobin, (a) The concentration of 02 is higher in the lungs and lower in the tissues. What effect does high [02] have on the position of this equilibrium? (b) The normal pH of blood is 7.4. Is the blood acidic, basic, or neutral? (c) If the blood pH is lowered by the presence of large amounts of acidic metabolism products, a condition known as acidosis results. What effect does lowering blood pH have on the ability of hemoglobin to transport 02?

Problem 104AE Calculate the pH of a solution made by adding 2.50 g of lithium oxide (Li20) to enough water to make 1.500 L of solution.

Benzoic acid \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\right) and aniline \(\left(C_{6} H_{5} N H_{2}\right)\) are both derivatives of benzene. Benzoic acid is an acid with \(K_{a}=6.3 \times 10^{-5}\) and aniline is a base with \(K_{a}=4.3 \times 10^{-10}\). (a) What are the conjugate base of benzoic acid and the conjugate acid of aniline? (b) Anilinium chloride \(\left.C_{6} H_{5} N H_{3} C I\right)\) is a strong electrolyte that dissociates into anilinium ions \(\left(C_{6} H_{5} N H_{3}^{+}\right)\) and chloride ions. Which will be more acidic, a 0.10 M solution of benzoic acid or a 0.10 M solution of anilinium chloride? (c) What is the value of the equilibrium constant for the following equilibrium? \(C_{6} H_{5} C O O H(a q)+C_{6} H_{5} N H_{2}(a q) \leftrightarrow C_{6} H_{5} C O O^{-}(a q)+C_{6} H_{5} N H_{3}^{+}(a q)\) Equation transcription: Text transcription: \left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\right) \left(C_{6} H_{5} N H_{2}\right) K_{a}=6.3 \times 10^{-5} K_{a}=4.3 \times 10^{-10} \left.C_{6} H_{5} N H_{3} C I\right) \left(C_{6} H_{5} N H_{3}^{+}\right) C_{6} H_{5} C O O H(a q)+C_{6} H_{5} N H_{2}(a q) \leftrightarrow C_{6} H_{5} C O O^{-}(a q)+C_{6} H_{5} N H_{3}^{+}(a q)

Problem 106AE What is the pH of a solution that is 2.5 x 10-9 M in NaOH? Does your answer make sense? What assumption do we normally make that is not valid in this case?

Problem 107AE Oxalic acid (H2C204) is a diprotic acid. By using data in Appendix D as needed, determine whether each of the following statements is true: (a) H2C204 can serve as both a Bronsted-Lowry acid and a Bronsted-Lowry base, (b) C204 2- is the conjugate base of HC204-. (c) An aqueous solution of the strong electrolyte KHC204 will have pH<7.

Succinic acid \(\left(\mathrm{H}_{2} \mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{4}\right)\), which we will denote \(\mathrm{H}_{2} \mathrm{Suc}\), is a biologically relevant diprotic acid with the structure shown below. It is closely related to tartaric acid and malic acid (Figure 16.1). At \(25^{\circ} \mathrm{C}\), the acid-dissociation constants for succinic acid are \(K_{a 1}=6.9 \times 10^{-5} \text { and } K_{a 2}=2.5 \times 10^{-6}\). (a) Determine the pH of a 0.32 M solution of \(\mathrm{H}_{2} \mathrm{Suc}\) at \(25^{\circ} \mathrm{C}\), assuming that only the first dissociation is relevant. (b) Determine the molar concentration of \(\text { Suc }^{2-}\) in the solution in part (a). (c) Is the assumption you made in part (a) justified by the result from part (b)? (d) Will a solution of the salt NaHSuc be acidic, neutral, or basic? Equation Transcription: Text Transcription: (H2C4H6O4) H2Suc 25°C Ka1=6.9 x 10-5 and Ka2=2.5 x 10-6 H2Suc 25°C Suc2-

Problem 109AE Butyric acid is responsible for the foul smell of rancid butter. The pKa of butyric acid is 4.84. (a) Calculate the pKb for the butyrate ion. (b) Calculate the pH of a 0.050 M solution of butyric acid, (c) Calculate the pH of a 0.050 M solution of sodium butyrate.

Problem 110AE Arrange the following 0.10 M solutions in order of increasing acidity (decreasing pH): (i) NH4N03, (ii) NaN03, (iii) CH3COONH4, (iv) NaF, (v) CH3COONa.

Problem 111AE A 0.25 M solution of a salt Na A has pH = 9.29. What is the value of Ka for the parent acid HA?

Problem 112AE The following observations are made about a diprotic acid H2A: (i) A 0.10 M solution of H2A has pH = 3.30. (ii) A 0.10 M solution of the salt NaHA is acidic. Which of the following could be the value of pKa2 for H2A: (i) 3.22, (ii) 5.30, (iii) 7.47, or (iv) 9.32?

Problem 113AE Many moderately large organic molecules containing basic nitrogen atoms are not very soluble in water as neutral molecules, but they are frequently much more soluble as their acid salts. Assuming that pH in the stomach is 2.5, indicate whether each of the following compounds would be present in the stomach as the neutral base or in the protonated form: nicotine, Kb = 7 x 10-7; caffeine, Kb = 4 x 10-14; strychnine, Kb = 1 x 10-6; quinine, Kb = 1.1 x 10-6.

The amino acid glycine (H2N?CH2?COOH) can participate in the following equilibria in water: \(H_{2}-C H_{2}-C O O H+H_{2} O \leftrightarrow H_{2} N-C H_{2}-\mathrm{COO}^{-}+H_{3} O^{+}\) \(K_{a}=4.3 x 10^{-3}\) \(H_{2}-\mathrm{CH}_{2}-\mathrm{COOH}+{ }^{+} \mathrm{H}_{3} \mathrm{~N}-\mathrm{CH}_{2}-\mathrm{COOH}+\mathrm{OH}^{-}\) \(K_{b}=6.0 \times 10^{-5}\) (a) Use the values of Ka and Kb to estimate the equilibrium constant for the intramolecular proton transfer to form a zwitterion: \(H_{2} N-C H_{2}-C 00 H \leftrightarrow^{+} H_{3} N-C H_{2}-C 00^{-}\) (b) What is the pH of a 0.050 M aqueous solution of glycine? (c) What would be the predominant form of glycine in a solution with pH 13? With pH 1? Equation transcription: Text transcription: H_{2}-C H_{2}-C O O H+H_{2} O \leftrightarrow H_{2} N-C H_{2}-\mathrm{COO}^{-}+H_{3} O^{+} K_{a}=4.3 x 10^{-3} H_{2}-\mathrm{CH}_{2}-\mathrm{COOH}+{ }^{+} \mathrm{H}_{3} \mathrm{~N}-\mathrm{CH}_{2}-\mathrm{COOH}+\mathrm{OH}^{-} K_{b}=6.0 \times 10^{-5} H_{2} N-C H_{2}-C 00 H \leftrightarrow^{+} H_{3} N-C H_{2}-C 00^{-}

The structural formula for acetic acid is shown in Table 16.2. Replacing hydrogen atoms on the carbon with chlorine atoms causes an increase in acidity, as follows: Using Lewis structures as the basis of your discussion, explain the observed trend in acidities in the series. Calculate the pH of a 0.010 M solution of each acid.

Problem 116AE Calculate the number of ions in 1.0 mL of pure water at 25 °C

Problem 117IE How many milliliters of concentrated hydrochloric acid solution (36.0% HCI by mass, density = 1.18 g/mL) are required to produce 10.0 L of a solution that has a pH of 2.05?

Problem 118IE The volume of an adult’s stomach ranges from about 50 mL when empty to 1 L when full. If the stomach volume is 400 mL and its contents have a pH of 2. how many moles of H+ does the stomach contain? Assuming that all the H+ comes from HCI. how many grams of sodium hydrogen carbonate will totally neutralize the stomach acid?

Problem 119IE Atmospheric C02 levels have risen by nearly 20% over the past 40 years from 315 ppm to 380 ppm. (a) Given that the average pH of clean, unpolluted rain today is 5.4, determine the pH of unpolluted rain 40 years ago. Assume that carbonic acid (H2C03) formed by the reaction of C02 and water is the only factor influencing pH. CO2(g) + H2O(l) ? H2CO3(aq) (b) What volume of C02 at 25 °C and 1.0 atm is dissolved in a 20.0-L bucket of today’s rainwater?

At 50°C, the ion-product constant for \(\mathrm{H}_{2} \mathrm{O}\) has the value \(K_{W}=5.48 \times 10^{-14}\). (a) What is the pH of pure water at 50°C? (b) Based on the change in \(K_{W}\) with temperature, predict whether ?H is positive, negative, or zero for the autoionization reaction of water: 2 H2O(l) ? H3O+(aq) + OH?(aq) Equation transcription: Text transcription: {H}_{2} {O} K_{W}=5.48 \times 10^{-14} K_{W}

Problem 121IE In many reactions the addition of A1CI3 produces the same effect as the addition of H+. (a) Draw a Lewis structure for AICI3 in which no atoms carry formal charges, and determine its structure using the VSEPR method, (b) What characteristic is notable about the structure in part (a) that helps us understand the acidic character of A1CI3? (c) Predict the result of the reaction between AICI3 and NH3 in a solvent that does not participate as a reactant, (d) Which acid-base theory is most suitable for discussing the similarities between AICI3 and H+?

Problem 122IE What is the boiling point of a 0.10 M solution of NaHS04 if the solution has a density of 1.002 g/mL?

Use average bond enthalpies from Table 8.4 to estimate the enthalpies of the following gas-phase reactions: Reaction 1: \(H F(g)+H_{2} O(g) \leftrightarrow F^{-}(g)+H_{3} O^{+}(g)\) Reaction 2: \(H C I(g)+H_{2} O(g) \leftrightarrow C I^{-}(g)+H_{2} O^{+}(g)\) Are both reactions exothermic? How do these values relate to the different strengths of hydrofluoric and hydrochloric acid? Equation transcription: Text transcription: H F(g)+H{2} O(g) leftrightarrow F^{-}(g)+H{3} O^{+}(g) H C I(g)+H{2} O(g) leftrightarrow C I^{-}(g)+H{2} O^{+}(g)

Problem 124IE Cocaine is a weak organic base whose molecular formula is C17H21N04. An aqueous solution of cocaine was found to have a pH of 8.53 and an osmotic pressure of 52.7 torr at 15 °C. Calculate Kb for cocaine.

The iodate ion is reduced by sulfite according to the following reaction: \(I O_{3}^{-}(a q)+3 S O_{3}^{2-}(a q) \rightarrow I^{-}(a q)+3 S O_{4}^{2-}(a q)\) The rate of this reaction is found to be first order in \(\mathrm{IO}_{3}^{-}\), first order in \(\mathrm{SO}_{3}^{2-}\), and first order in \(H^{+}\). (a) Write the rate law for the reaction. (b) By what factor will the rate of the reaction change if the pH is lowered from 5.00 to 3.50? Does the reaction proceed more quickly or more slowly at the lower pH? (c) By using the concepts discussed in Section 14.6, explain how the reaction can be pH-dependent even though H+ does not appear in the overall reaction. Equation transcription: Text transcription: I O_{3}^{-}(a q)+3 S O_{3}^{2-}(a q) rightarrow I^{-}(a q)+3 S O_{4}^{2-}(a q) {IO}_{3}^{-} {SO}_{3}^{2-} H^{+}

(a) Using dissociation constants from Appendix D, determine the value for the equilibrium constant for each of the following reactions. (i) \(\mathrm{HCO}_{3}^{-}(a q)+\mathrm{OH}^{-}(a q) \leftrightarrow \mathrm{CO}_{3}^{2-}(a q)+\mathrm{H}_{2} \mathrm{O}(\mathrm{I})\) (ii) \(\mathrm{NH}_{4}^{+}(a q)+\mathrm{CO}_{3}^{2-}(a q) \leftrightarrow \mathrm{NH}_{3}(a q)+\mathrm{NCO}_{3}^{-}(a q)\) (b) We usually use single arrows for reactions when the forward reaction is appreciable (K much greater than 1) or when products escape from the system, so that equilibrium is never established. If we follow this convention, which of these equilibria might be written with a single arrow? Equation transcription: Text transcription: {HCO}_{3}^{-}(a q)+{OH}^{-}(a q) \leftrightarrow{CO}_{3}^{2-}(a q)+{H}_{2}{O}({I}) {NH}_{4}^{+}(a q)+{CO}_{3}^{2-}(a q) leftrightarrow{NH}_{3}(a q)+{NCO}_{3}^{-}(a q)

Problem 79E The Ka- Kb Relationship; Acid-Base Properties of Salts (Sections) Using data from Appendix D. calculate [OH-] and pH for each of the following solutions; (a) 0.10 M NaBrO. (b) 0.080 M NaHS. (c) a mixture that is 0.10 M in NaN02 and 0.20 M in Ca(N02)2.