Solved: Explain what is meant by the strength of an acid

Define Brnsted acids and bases. Give an example of a conjugate pair in an acid-base reaction

In order for a species to act as a Brnsted base, an atom in the species must possess a lone pair of electrons. Explain why this is so.

Classify each of the following species as a Brnsted acid or base, or both: (a) H2O, (b) OH2, (c) H3O1, (d) NH3, (e) NH4 1, (f) NH2 2, (g) NO3 2, (h) CO3 22, (i) HBr, ( j) HCN. Unless otherwise stated, the temperature is assumed to be 25C.

Write the formulas of the conjugate bases of the following acids: (a) HNO2, (b) H2SO4, (c) H2S, (d) HCN, (e) HCOOH (formic acid).

Identify the acid-base conjugate pairs in each of the following reactions: (a) CH3COO2 1 HCN CH3COOH 1 CN2 (b) HCO2 3 1 HCO2 3 H2CO3 1 CO22 3 (c) H2PO2 4 1 NH3 HPO22 4 1 NH1 4 (d) HClO 1 CH3NH2 CH3NH1 3 1 ClO2 (e) CO22 3 1 H2O HCO3 2 1 OH2

Write the formula for the conjugate acid of each of the following bases: (a) HS2, (b) HCO3 2, (c) CO3 22, (d) H2PO4 2, (e) HPO4 22, (f) PO4 32, (g) HSO4 2, (h) SO4 22, (i) SO3 22.

Oxalic acid (H2C2O4) has the following structure: OPCOOH A OPCOOH An oxalic acid solution contains the following species in varying concentrations: H2C2O4, HC2O4 2, C2O4 22, and H1. (a) Draw Lewis structures of HC2O4 2, and C2O4 22. (b) Which of the above four species can act only as acids, which can act only as bases, and which can act as both acids and bases?

Write the formula for the conjugate base of each of the following acids: (a) CH2ClCOOH, (b) HIO4, (c) H3PO4, (d) H2PO2 4 , (e) HPO22 4 , (f) H2SO4, (g) HSO4 2, (h) HIO3, (i) HSO3 2, (j) NH4 1, (k) H2S, (l) HS2, (m) HClO.

What is the ion-product constant for water?

Write an equation relating [H1] and [OH2] in solution at 25C.

The ion-product constant for water is 1.0 3 10214 at 25C and 3.8 3 10214 at 40C. Is the forward process H2O(l) H1(aq) 1 OH2(aq) endothermic or exothermic?

Define pH. Why do chemists normally choose to discuss the acidity of a solution in terms of pH rather than hydrogen ion concentration, [H1]?

The pH of a solution is 6.7. From this statement alone, can you conclude that the solution is acidic? If not, what additional information would you need? Can the pH of a solution be zero or negative? If so, give examples to illustrate these values

Define pOH. Write the equation relating pH and pOH.

Calculate the concentration of OH2 ions in a 1.4 3 1023 M HCl solution

Calculate the concentration of H1 ions in a 0.62 M NaOH solution

Calculate the pH of each of the following solutions: (a) 0.0010 M HCl, (b) 0.76 M KOH.

Calculate the pH of each of the following solutions: (a) 2.8 3 1024 M Ba(OH)2, (b) 5.2 3 1024 M HNO3.

Calculate the hydrogen ion concentration in mol/L for solutions with the following pH values: (a) 2.42, (b) 11.21, (c) 6.96, (d) 15.00.

Calculate the hydrogen ion concentration in mol/L for each of the following solutions: (a) a solution whose pH is 5.20, (b) a solution whose pH is 16.00, (c) a solution whose hydroxide concentration is 3.7 3 1029 M.

Complete the following table for a solution: pH [H1] Solution is ,7 ,1.0 3 1027 M Neutral

Fill in the word acidic, basic, or neutral for the following solutions: (a) pOH . 7; solution is (b) pOH 5 7; solution is (c) pOH , 7; solution is

The pOH of a strong base solution is 1.88 at 25C. Calculate the concentration of the base (a) if the base is KOH and (b) if the base is Ba(OH)2.

Calculate the number of moles of KOH in 5.50 mL of a 0.360 M KOH solution. What is the pOH of the solution?

How much NaOH (in grams) is needed to prepare 546 mL of solution with a pH of 10.00?

A solution is made by dissolving 18.4 g of HCl in 662 mL of water. Calculate the pH of the solution. (Assume that the volume remains constant.)

Explain what is meant by the strength of an acid

Without referring to the text, write the formulas of four strong acids and four weak acids.

What are the strongest acid and strongest base that can exist in water?

H2SO4 is a strong acid, but HSO4 2 is a weak acid. Account for the difference in strength of these two related species.

Which of the following diagrams best represents a strong acid, such as HCl, dissolved in water? Which represents a weak acid? Which represents a very weak acid? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.) (a) (b) (c) (d)

(1) Which of the following diagrams represents a solution of a weak diprotic acid? (2) Which diagrams represent chemically implausible situations? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.) (a) (b) (c) (d)

Classify each of the following species as a weak or strong acid: (a) HNO3, (b) HF, (c) H2SO4, (d) HSO4 2, (e) H2CO3, (f) HCO3 2, (g) HCl, (h) HCN, (i) HNO2.

Classify each of the following species as a weak or strong base: (a) LiOH, (b) CN2, (c) H2O, (d) ClO4 2, (e) NH2 2.

Which of the following statements is/are true for a 0.10 M solution of a weak acid HA? (a) The pH is 1.00. (b) [H1] @ [A2] (c) [H1] 5 [A2] (d) The pH is less than 1

Which of the following statements is/are true regarding a 1.0 M solution of a strong acid HA? (a) [A2] . [H1] (b) The pH is 0.00. (c) [H1] 5 1.0 M (d) [HA] 5 1.0 M

Predict the direction that predominates in this reaction: F2(aq) 1 H2O(l) HF(aq) 1 OH2(aq)

Predict whether the following reaction will proceed from left to right to any measurable extent: CH3COOH(aq) 1 Cl2(aq)

What does the ionization constant tell us about the strength of an acid?

List the factors on which the Ka of a weak acid depends.

Why do we normally not quote Ka values for strong acids such as HCl and HNO3? Why is it necessary to specify temperature when giving Ka values?

Which of the following solutions has the highest pH? (a) 0.40 M HCOOH, (b) 0.40 M HClO4, (c) 0.40 M CH3COOH.

The Ka for benzoic acid is 6.5 3 1025 . Calculate the pH of a 0.10 M benzoic acid solution.

A 0.0560-g quantity of acetic acid is dissolved in enough water to make 50.0 mL of solution. Calculate the concentrations of H1, CH3COO2, and CH3COOH at equilibrium. (Ka for acetic acid 5 1.8 3 1025 .)

The pH of an acid solution is 6.20. Calculate the Ka for the acid. The initial acid concentration is 0.010 M.

What is the original molarity of a solution of formic acid (HCOOH) whose pH is 3.26 at equilibrium?

Calculate the percent ionization of benzoic acid having the following concentrations: (a) 0.20 M, (b) 0.00020 M.

Calculate the percent ionization of hydrofluoric acid at the following concentrations: (a) 0.60 M, (b) 0.0046 M, (c) 0.00028 M. Comment on the trends.

A 0.040 M solution of a monoprotic acid is 14 percent ionized. Calculate the ionization constant of the acid.

(a) Calculate the percent ionization of a 0.20 M solution of the monoprotic acetylsalicylic acid (aspirin) for which Ka 5 3.0 3 1024 . (b) The pH of gastric juice in the stomach of a certain individual is 1.00. After a few aspirin tablets have been swallowed, the concentration of acetylsalicylic acid in the stomach is 0.20 M. Calculate the percent ionization of the acid under these conditions. What effect does the nonionized acid have on the membranes lining the stomach? (Hint: See the Chemistry in Action essay on p. 706.)

Use NH3 to illustrate what we mean by the strength of a base.

Which of the following has a higher pH? (a) 0.20 M NH3, (b) 0.20 M NaOH

Calculate the pH of a 0.24 M solution of a weak base with a Kb of 3.5 3 1026

The diagrams here represent three different weak base solutions of equal concentration. List the bases in order of increasing Kb value. (Water molecules are omitted for clarity.) (a) (b) (c) B HB1 OH2

Calculate the pH for each of the following solutions: (a) 0.10 M NH3, (b) 0.050 M C5H5N (pyridine).

The pH of a 0.30 M solution of a weak base is 10.66. What is the Kb of the base?

What is the original molarity of a solution of ammonia whose pH is 11.22?

In a 0.080 M NH3 solution, what percent of the NH3 is present as NH4 1?

Write the equation relating Ka for a weak acid and Kb for its conjugate base. Use NH3 and its conjugate acid NH4 1 to derive the relationship between Ka and Kb.

From the relationship KaKb 5 Kw, what can you deduce about the relative strengths of a weak acid and its conjugate base?

Carbonic acid is a diprotic acid. Explain what that means

Write all the species (except water) that are present in a phosphoric acid solution. Indicate which species can act as a Brnsted acid, which as a Brnsted base, and which as both a Brnsted acid and a Brnsted base.

The first and second ionization constants of a diprotic acid H2A are Ka1 and Ka2 at a certain temperature. Under what conditions will [A22] 5 Ka2 ?

Compare the pH of a 0.040 M HCl solution with that of a 0.040 M H2SO4 solution. (Hint: H2SO4 is a strong acid; Ka for HSO4 2 5 1.3 3 1022 .)

What are the concentrations of HSO4 2, SO4 22, and H1 in a 0.20 M KHSO4 solution?

Calculate the concentrations of H1, HCO3 2, and CO3 22 in a 0.025 M H2CO3 solution.

List four factors that affect the strength of an acid.

How does the strength of an oxoacid depend on the electronegativity and oxidation number of the central atom?

Predict the acid strengths of the following compounds: H2O, H2S, and H2Se.

Compare the strengths of the following pairs of acids: (a) H2SO4 and H2SeO4, (b) H3PO4 and H3AsO4.

Which of the following is the stronger acid: CH2ClCOOH or CHCl2COOH? Explain your choice.

Consider the following compounds: OOOH CH3OOOH phenol methanol Experimentally, phenol is found to be a stronger acid than methanol. Explain this difference in terms of the structures of the conjugate bases. (Hint: A more stable conjugate base favors ionization. Only one of the conjugate bases can be stabilized by resonance.)

Define salt hydrolysis. Categorize salts according to how they affect the pH of a solution.

Explain why small, highly charged metal ions are able to undergo hydrolysis

Al31 is not a Brnsted acid but Al(H2O)31 6 is. Explain

Specify which of the following salts will undergo hydrolysis: KF, NaNO3, NH4NO2, MgSO4, KCN, C6H5COONa, RbI, Na2CO3, CaCl2, HCOOK.

Predict the pH (. 7, , 7, or < 7) of aqueous solutions containing the following salts: (a) KBr, (b) Al(NO3)3, (c) BaCl2, (d) Bi(NO3)3.

Predict whether the following solutions are acidic, basic, or nearly neutral: (a) NaBr, (b) K2SO3, (c) NH4NO2, (d) Cr(NO3)3

A certain salt, MX (containing the M1 and X2 ions), is dissolved in water, and the pH of the resulting solution is 7.0. Can you say anything about the strengths of the acid and the base from which the salt is derived?

In a certain experiment a student finds that the pHs of 0.10 M solutions of three potassium salts KX, KY, and KZ are 7.0, 9.0, and 11.0, respectively. Arrange the acids HX, HY, and HZ in the order of increasing acid strength.

Calculate the pH of a 0.36 M CH3COONa solution.

Calculate the pH of a 0.42 M NH4Cl solution.

Predict the pH (. 7, , 7, < 7) of a NaHCO3 solution.

Predict whether a solution containing the salt K2HPO4 will be acidic, neutral, or basic.

Classify the following oxides as acidic, basic, amphoteric, or neutral: (a) CO2, (b) K2O, (c) CaO, (d) N2O5, (e) CO, (f) NO, (g) SnO2, (h) SO3, (i) Al2O3, (j) BaO.

Write equations for the reactions between (a) CO2 and NaOH(aq), (b) Na2O and HNO3(aq).

Explain why metal oxides tend to be basic if the oxidation number of the metal is low and acidic if the oxidation number of the metal is high. (Hint: Metallic compounds in which the oxidation numbers of the metals are low are more ionic than those in which the oxidation numbers of the metals are high.)

Arrange the oxides in each of the following groups in order of increasing basicity: (a) K2O, Al2O3, BaO, (b) CrO3, CrO, Cr2O3

Zn(OH)2 is an amphoteric hydroxide. Write balanced ionic equations to show its reaction with (a) HCl, (b) NaOH [the product is Zn(OH)4 22].

Al(OH)3 is an insoluble compound. It dissolves in excess NaOH in solution. Write a balanced ionic equation for this reaction. What type of reaction is this?

What are the Lewis definitions of an acid and a base? In what way are they more general than the Brnsted definitions?

In terms of orbitals and electron arrangements, what must be present for a molecule or an ion to act as a Lewis acid (use H1 and BF3 as examples)? What must be present for a molecule or ion to act as a Lewis base (use OH2 and NH3 as examples)

Classify each of the following species as a Lewis acid or a Lewis base: (a) CO2, (b) H2O, (c) I2, (d) SO2, (e) NH3, (f) OH2, (g) H1, (h) BCl3.

Describe the following reaction in terms of the Lewis theory of acids and bases: AlCl3(s) 1 CI2(aq) AlCl2 4 (aq)

Which would be considered a stronger Lewis acid: (a) BF3 or BCl3, (b) Fe21 or Fe31? Explain.

All Brnsted acids are Lewis acids, but the reverse is not true. Give two examples of Lewis acids that are not Brnsted acids.

Determine the concentration of a NaNO2 solution that has a pH of 8.22

Determine the concentration of a NH4Cl solution that has a pH of 5.64.

The diagrams here show three weak acids HA (A 5 X, Y, or Z) in solution. (a) Arrange the acids in order of increasing Ka. (b) Arrange the conjugate bases in increasing order of Kb. (c) Calculate the percent ionization of each acid. (d) Which of the 0.1 M sodium salt solutions (NaX, NaY, or NaZ) has the lowest pH? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.) HX HY HZ

A typical reaction between an antacid and the hydrochloric acid in gastric juice is NaHCO3(s) 1 HCl(aq) NaCl(aq) 1 H2O(l) 1 CO2(g) Calculate the volume (in L) of CO2 generated from 0.350 g of NaHCO3 and excess gastric juice at 1.00 atm and 37.0C

To which of the following would the addition of an equal volume of 0.60 M NaOH lead to a solution having a lower pH? (a) water, (b) 0.30 M HCl, (c) 0.70 M KOH, (d) 0.40 M NaNO3.

The pH of a 0.0642 M solution of a monoprotic acid is 3.86. Is this a strong acid?

Like water, liquid ammonia undergoes autoionization: NH3 1 NH3 NH1 4 1 NH2 2 (a) Identify the Brnsted acids and Brnsted bases in this reaction. (b) What species correspond to H1 and OH2 and what is the condition for a neutral solution?

HA and HB are both weak acids although HB is the stronger of the two. Will it take a larger volume of a 0.10 M NaOH solution to neutralize 50.0 mL of 0.10 M HB than would be needed to neutralize 50.0 mL of 0.10 M HA?

A solution contains a weak monoprotic acid HA and its sodium salt NaA both at 0.1 M concentration. Show that [OH2] 5 Kw/Ka.

The three common chromium oxides are CrO, Cr2O3, and CrO3. If Cr2O3 is amphoteric, what can you say about the acid-base properties of CrO and CrO3?

Use the data in Table 15.3 to calculate the equilibrium constant for the following reaction: HCOOH(aq) 1 OH2(aq) HCOO2(aq) 1 H2O(l2

Use the data in Table 15.3 to calculate the equilibrium constant for the following reaction: CH3COOH(aq) 1 NO2 2 (aq) CH3COO2(aq) 1 HNO2(aq)

Most of the hydrides of Group 1A and Group 2A metals are ionic (the exceptions are BeH2 and MgH2, which are covalent compounds). (a) Describe the reaction between the hydride ion (H2) and water in terms of a Brnsted acid-base reaction. (b) The same reaction can also be classified as a redox reaction. Identify the oxidizing and reducing agents

Calculate the pH of a 0.20 M ammonium acetate (CH3COONH4) solution.

Novocaine, used as a local anesthetic by dentists, is a weak base (Kb 5 8.91 3 1026 ). What is the ratio of the concentration of the base to that of its acid in the blood plasma (pH 5 7.40) of a patient?

Which of the following is the stronger base: NF3 or NH3? (Hint: F is more electronegative than H.)

Which of the following is a stronger base: NH3 or PH3? (Hint: The NH bond is stronger than the PH bond.)

The ion product of D2O is 1.35 3 10215 at 25C. (a) Calculate pD where pD 5 2log [D1]. (b) For what values of pD will a solution be acidic in D2O? (c) Derive a relation between pD and pOD

Give an example of (a) a weak acid that contains oxygen atoms, (b) a weak acid that does not contain oxygen atoms, (c) a neutral molecule that acts as a Lewis acid, (d) a neutral molecule that acts as a Lewis base, (e) a weak acid that contains two ionizable H atoms, (f) a conjugate acid-base pair, both of which react with HCl to give carbon dioxide gas.

What is the pH of 250.0 mL of an aqueous solution containing 0.616 g of the strong acid trifluoromethane sulfonic acid (CF3SO3H)?

(a) Use VSEPR to predict the geometry of the hydronium ion, H3O1. (b) The O atom in H2O has two lone pairs and in principle can accept two H1 ions. Explain why the species H4O21 does not exist. What would be its geometry if it did exist?

HF is a weak acid, but its strength increases with concentration. Explain. (Hint: F2 reacts with HF to form HF2 2. The equilibrium constant for this reaction is 5.2 at 25C.)

When chlorine reacts with water, the resulting solution is weakly acidic and reacts with AgNO3 to give a white precipitate. Write balanced equations to represent these reactions. Explain why manufacturers of household bleaches add bases such as NaOH to their products to increase their effectiveness.

When the concentration of a strong acid is not substantially higher than 1.0 3 1027 M, the ionization of water must be taken into account in the calculation of the solutions pH. (a) Derive an expression for the pH of a strong acid solution, including the contribution to [H1] from H2O. (b) Calculate the pH of a 1.0 3 1027 M HCl solution.

Calculate the pH of a 2.00 M NH4CN solution

Calculate the concentrations of all species in a 0.100 M H3PO4 solution.

Identify the Lewis acid and Lewis base that lead to the formation of the following species: (a) AlCl2 4 , (b) Cd(CN)22 4 , (c) HCO2 3 , (d) H2SO4.

Very concentrated NaOH solutions should not be stored in Pyrex glassware. Why? (Hint: See Section 11.7.

In the vapor phase, acetic acid molecules associate to a certain extent to form dimers: 2CH3COOH(g) (CH3COOH)2(g) At 51C the pressure of a certain acetic acid vapor system is 0.0342 atm in a 360-mL flask. The vapor is condensed and neutralized with 13.8 mL of 0.0568 M NaOH. (a) Calculate the degree of dissociation () of the dimer under these conditions: (CH3COOH)2 2CH3COOH (Hint: See Problem 14.117 for general procedure.) (b) Calculate the equilibrium constant KP for the reaction in (a).

Calculate the concentrations of all the species in a 0.100 M Na2CO3 solution.

Henrys law constant for CO2 at 38C is 2.28 3 1023 mol/L ? atm. Calculate the pH of a solution of CO2 at 38C in equilibrium with the gas at a partial pressure of 3.20 atm.

Hydrocyanic acid (HCN) is a weak acid and a deadly poisonous compoundin the gaseous form (hydrogen cyanide) it is used in gas chambers. Why is it dangerous to treat sodium cyanide with acids (such as HCl) without proper ventilation?

How many grams of NaCN would you need to dissolve in enough water to make exactly 250 mL of solution with a pH of 10.00?

A solution of formic acid (HCOOH) has a pH of 2.53. How many grams of formic acid are there in 100.0 mL of the solution?

Calculate the pH of a 1-L solution containing 0.150 mole of CH3COOH and 0.100 mole of HCl.

A 1.87-g sample of Mg reacts with 80.0 mL of a HCl solution whose pH is 20.544. What is the pH of the solution after all the Mg has reacted? Assume constant volume

You are given two beakers, one containing an aqueous solution of strong acid (HA) and the other an aqueous solution of weak acid (HB) of the same concentration. Describe how you would compare the strengths of these two acids by (a) measuring the pH, (b) measuring electrical conductance, (c) studying the rate of hydrogen gas evolution when these solutions are reacted with an active metal such as Mg or Zn.

Use Le Chteliers principle to predict the effect of the following changes on the extent of hydrolysis of sodium nitrite (NaNO2) solution: (a) HCl is added, (b) NaOH is added, (c) NaCl is added, (d) the solution is diluted

Describe the hydration of SO2 as a Lewis acid-base reaction. (Hint: Refer to the discussion of the hydration of CO2 on p. 705.)

The disagreeable odor of fish is mainly due to organic compounds (RNH2) containing an amino group, NH2, where R is the rest of the molecule. Amines are bases just like ammonia. Explain why putting some lemon juice on fish can greatly reduce the odor

A solution of methylamine (CH3NH2) has a pH of 10.64. How many grams of methylamine are there in 100.0 mL of the solution?

A 0.400 M formic acid (HCOOH) solution freezes at 20.758C. Calculate the Ka of the acid at that temperature. (Hint: Assume that molarity is equal to molality. Carry your calculations to three significant figures and round off to two for Ka.)

Both the amide ion (NH2 2) and the nitride ion (N32) are stronger bases than the hydroxide ion and hence do not exist in aqueous solutions. (a) Write equations showing the reactions of these ions with water, and identify the Brnsted acid and base in each case. (b) Which of the two is the stronger base?

The atmospheric sulfur dioxide (SO2) concentration over a certain region is 0.12 ppm by volume. Calculate the pH of the rainwater due to this pollutant. Assume that the dissolution of SO2 does not affect its pressure.

Calcium hypochlorite [Ca(OCl)2] is used as a disinfectant for swimming pools. When dissolved in water it produces hypochlorous acid Ca(OCl)2(s) 1 2H2O(l) 2HClO(aq) 1 Ca(OH)2(s) which ionizes as follows: HClO(aq) H1(aq) 1 ClO2(aq) Ka 5 3.0 3 1028 As strong oxidizing agents, both HClO and ClO2 can kill bacteria by destroying their cellular components. However, too high a HClO concentration is irritating to the eyes of swimmers and too high a concentration of ClO2 will cause the ions to decompose in sunlight. The recommended pH for pool water is 7.8. Calculate the percent of these species present at this pH.

Explain the action of smelling salt, which is ammonium carbonate [(NH4)2CO3]. (Hint: The thin film of aqueous solution that lines the nasal passage is slightly basic.)

About half of the hydrochloric acid produced annually in the United States (3.0 billion pounds) is used in metal pickling. This process involves the removal of metal oxide layers from metal surfaces to prepare them for coating. (a) Write the overall and net ionic equations for the reaction between iron(III) oxide, which represents the rust layer over iron, and HCl. Identify the Brnsted acid and base. (b) Hydrochloric acid is also used to remove scale (which is mostly CaCO3) from water pipes (see p. 126). Hydrochloric acid reacts with calcium carbonate in two stages; the first stage forms the bicarbonate ion, which then reacts further to form carbon dioxide. Write equations for these two stages and for the overall reaction. (c) Hydrochloric acid is used to recover oil from the ground. It dissolves rocks (often CaCO3) so that the oil can flow more easily. In one process, a 15 percent (by mass) HCl solution is injected into an oil well to dissolve the rocks. If the density of the acid solution is 1.073 g/mL, what is the pH of the solution?

Which of the following does not represent a Lewis acid-base reaction? (a) H2O 1 H1 H3O1 (b) NH3 1 BF3 H3NBF3 (c) PF3 1 F2 PF5 (d) Al(OH)3 1 OH2 Al(OH)4 2

True or false? If false, explain why the statement is wrong. (a) All Lewis acids are Brnsted acids, (b) the conjugate base of an acid always carries a negative charge, (c) the percent ionization of a base increases with its concentration in solution, (d) a solution of barium fluoride is acidic

How many milliliters of a strong monoprotic acid solution at pH 5 4.12 must be added to 528 mL of the same acid solution at pH 5 5.76 to change its pH to 5.34? Assume that the volumes are additive.

Calculate the pH and percent ionization of a 0.80 M HNO2 solution.

Consider the two weak acids HX (molar mass 5 180 g/mol) and HY (molar mass 5 78.0 g/mol). If a solution of 16.9 g/L of HX has the same pH as one containing 9.05 g/L of HY, which is the stronger acid at these concentrations?

Hemoglobin (Hb) is a blood protein that is responsible for transporting oxygen. It can exist in the protonated form as HbH1. The binding of oxygen can be represented by the simplified equation HbH1 1 O2 HbO2 1 H1 (a) What form of hemoglobin is favored in the lungs where oxygen concentration is highest? (b) In body tissues, where the cells release carbon dioxide produced by metabolism, the blood is more acidic due to the formation of carbonic acid. What form of 7 hemoglobin is favored under this condition? (c) When a person hyperventilates, the concentration of CO2 in his or her blood decreases. How does this action affect the above equilibrium? Frequently a person who is hyperventilating is advised to breathe into a paper bag. Why does this action help the individual?

A 1.294-g sample of a metal carbonate (MCO3) is reacted with 500 mL of a 0.100 M HCl solution. The excess HCl acid is then neutralized by 32.80 mL of 0.588 M NaOH. Identify M

Prove the statement that when the concentration of a weak acid HA decreases by a factor of 10, its percent ionization increases by a factor of 110. State any assumptions.

Calculate the pH of a solution that is 1.00 M HCN and 1.00 M HF. Compare the concentration (in molarity) of the CN2 ion in this solution with that in a 1.00 M HCN solution. Comment on the difference.

Teeth enamel is hydroxyapatite [Ca3(PO4)3OH]. When it dissolves in water (a process called demineralization), it dissociates as follows: Ca5(PO4)3OH 5Ca21 1 3PO4 32 1 OH2 The reverse process, called remineralization, is the bodys natural defense against tooth decay. Acids produced from food remove the OH2 ions and thereby weaken the enamel layer. Most toothpastes contain a fluoride compound such as NaF or SnF2. What is the function of these compounds in preventing tooth decay?

Use the vant Hoff equation (see Problem 14.119) and the data in Appendix 3 to calculate the pH of water at its normal boiling point

At 28C and 0.982 atm, gaseous compound HA has a density of 1.16 g/L. A quantity of 2.03 g of this compound is dissolved in water and diluted to exactly 1 L. If the pH of the solution is 5.22 (due to the ionization of HA) at 25C, calculate the Ka of the acid.

A 10.0-g sample of white phosphorus was burned in an excess of oxygen. The product was dissolved in enough water to make 500 mL of solution. Calculate the pH of the solution at 25C

Calculate the pH of a 0.20 M NaHCO3 solution. (Hint: As an approximation, calculate hydrolysis and ionization separately first, followed by partial neutralization.)

(a) Shown here is a solution containing hydroxide ions and hydronium ions. What is the pH of the solution? (b) How many H3O1 ions would you need to draw for every OH2 ion if the pH of the solution is 5.0? The color codes are H3O1 (red) and OH2 (green). Water molecules and counter ions are omitted for clarity

In this chapter, HCl, HBr, and HI are all listed as strong acids because they are assumed to be ionized completely in water. If, however, we choose a solvent such as acetic acid that is a weaker Brnsted base than water, it is possible to rank the acids in increasing strength as HCl , HBr , HI. (a) Write equations showing proton transfer between the acids and CH3COOH. Describe how you would compare the strength of the acids in this solvent experimentally. (b) Draw a Lewis structure of the conjugate acid CH3COOH1 2

Use the data in Appendix 3 to calculate the Hrxn for the following reactions: (a) NaOH(aq) 1 HCl(aq) S NaCl(aq) 1 H2O(l) and (b) KOH(aq) 1 HNO3(aq) S KNO3(aq) 1 H2O(l). Comment on your results.

Malonic acid [CH2(COOH)2] is a diprotic acid. Compare its two Ka values with that of acetic acid (CH3COOH) (Ka ), and account for the differences in the three Ka values.

Look up the contents of a Tums tablet. How many tablets are needed to increase the pH of the gastric juice in a persons stomach from 1.2 to 1.5?

Phosphorous acid, H3PO3(aq), is a diprotic acid with Ka1 5 3 3 1022 . (a) After examining the Ka values in Table 15.5, estimate Ka2 for H3PO3(aq) and calculate the pH of a 0.10 M solution of Na2HPO3(aq). (b) The structure of H3PO3 is given in Figure 15.5. Explain why H3PO4(aq) is a triprotic acid, but H3PO3(aq) is only a diprotic acid.

Chicken egg shells are composed primarily of calcium carbonate, CaCO3. In a classic demonstration carried out in chemistry and biology classes, vinegar is used to remove the shell from an uncooked egg, revealing the semipermeable membrane that surrounds the egg keeping it intact. Refer to the Chemical Mystery on p. 774 to see a schematic diagram of a chicken egg. Estimate the minimum amount of vinegar required to remove the entire shell from the egg