Solution: Consider a solution prepared by mixing a weak acid

Write the simple dissociation (ionization) reaction (omitting water) for each of the following acids. a. hydrochloric acid (HCl) b. acetic acid (HC2H3O2) c. the ammonium ion (NH4 1) d. the anilinium ion (C6H5NH3 1) e. the hydrated aluminum(III) ion [Al(H2O)6]31

Vinegar contains acetic acid and is used in salad dressings. What if acetic acid was a strong acid instead of a weak acid? Would it be safe to use vinegar as a salad dressing?

Using Table 14.2, arrange the following species according to their strengths as bases: H2O, F2, Cl2, NO2 2, and CN2.

Calculate [H1] or [OH2] as required for each of the following solutions at 258C, and state whether the solution is neutral, acidic, or basic. a. 1.0 3 1025 M OH2 b. 1.0 3 1027 M OH2 c. 10.0 M H1

At 608C, the value of Kw is 1 3 10213. a. Using Le Chteliers principle, predict whether the reaction 2H2O1l2mH3O1 1aq2 1 OH2 1aq2 is exothermic or endothermic. b. Calculate [H1] and [OH2] in a neutral solution at 608C.

What if you lived on a planet identical to the earth but for which room temperature was 508C? How would the pH scale be different?

Calculate pH and pOH for each of the following solutions at 258C. a. 1.0 3 1023 M OH2 b. 1.0 M OH

The pH of a sample of human blood was measured to be 7.41 at 258C. Calculate pOH, [H1], and [OH2] for the sample.

a. Calculate the pH of 0.10 M HNO3. b. Calculate the pH of 1.0 3 10210 M HCl

Consider two aqueous solutions of different weak acids, HA and HB. What if all you know about the two acids is that the Ka value for HA is greater than that for HB? Can you tell which of the acids is stronger than the other? Can you tell which of the acid solutions has the lower pH? Defend your answers.

The hypochlorite ion (OCl2) is a strong oxidizing agent often found in household bleaches and disinfectants. It is also the active ingredient that forms when swimmingpool water is treated with chlorine. In addition to its oxidizing abilities, the hypochlorite ion has a relatively high affinity for protons (it is a much stronger base than Cl2, for example) and forms the weakly acidic hypochlorous acid (HOCl, Ka 5 3.5 3 1028 ). Calculate the pH of a 0.100-M aqueous solution of hypochlorous acid.

Calculate the pH of a solution that contains 1.00 M HCN (Ka 5 6.2 3 10210) and 5.00 M HNO2 (Ka 5 4.0 3 1024 ). Also calculate the concentration of cyanide ion (CN2) in this solution at equilibrium.

Calculate the percent dissociation of acetic acid (Ka 5 1.8 3 1025 ) in each of the following solutions: a. 1.00 M HC2H3O2 b. 0.100 M HC2H3O2

Lactic acid (HC3H5O3) is a chemical that accumulates in muscle tissue during exertion. In a 0.100-M aqueous solution, lactic acid is 3.7% dissociated. Calculate the value of Ka for this acid.

Calculate the pH of a 5.0 3 1022 -M NaOH solution

Calculate the pH for a 15.0-M solution of NH3 (Kb 5 1.8 3 1025 ).

Calculate the pH of a 1.0-M solution of methylamine (Kb 5 4.38 3 1024 )

Calculate the pH of a 5.0-M H3PO4 solution and the equilibrium concentrations of the species H3PO4, H2PO4 2, HPO4 22, and PO4 32.

What if the three values of Ka for phosphoric acid were closer to each other in value? Why would this complicate the calculation of the pH for an aqueous solution of phosphoric acid?

Calculate the pH of a 1.0-M H2SO4 solution.

Calculate the pH of a 1.00 3 1022 M H2SO4 solution.

Calculate the pH of a 0.30-M NaF solution. The Ka value for HF is 7.2 3 1024

Calculate the pH of a 0.10-M NH4Cl solution. The Kb value for NH3 is 1.8 3 1025 .

Calculate the pH of a 0.010-M AlCl3 solution. The Ka value for Al(H2O)6 31 is 1.4 3 1025 .

Predict whether an aqueous solution of each of the following salts will be acidic, basic, or neutral. a. NH4C2H3O2 b. NH4CN c. Al2(SO4)3

For each reaction, identify the Lewis acid and base. a. Ni21 1aq2 1 6NH3 1aq2 h Ni1NH32 6 21 1aq2 b. H1 1aq2 1 H2O1aq2mH3O1 1aq2

Define each of the following: a. Arrhenius acid b. BrnstedLowry acid c. Lewis acid Which of the definitions is most general? Write reactions to justify your answer.

Define or illustrate the meaning of the following terms: a. Ka reaction b. Ka equilibrium constant c. Kb reaction d. Kb equilibrium constant e. conjugate acidbase pair

Define or illustrate the meaning of the following terms: a. amphoteric b. Kw reaction c. Kw equilibrium constant d. pH e. pOH f. pKw Give the conditions for a neutral aqueous solution at 258C, in terms of [H1], pH, and the relationship between [H1] and [OH2]. Do the same for an acidic solution and for a basic solution. As a solution becomes more acidic, what happens to pH, pOH, [H1], and [OH2]? As a solution becomes more basic, what happens to pH, pOH, [H1], and [OH2]?

How is acid strength related to the value of Ka? What is the difference between strong acids and weak acids (see Table 14.1)? As the strength of an acid increases, what happens to the strength of the conjugate base? How is base strength related to the value of Kb? As the strength of a base increases, what happens to the strength of the conjugate acid?

Two strategies are followed when solving for the pH of an acid in water. What is the strategy for calculating the pH of a strong acid in water? What major assumptions are made when solving strong acid problems? The best way to recognize strong acids is to memorize them. List the six common strong acids (the two not listed in the text are HBr and HI). Most acids, by contrast, are weak acids. When solving for the pH of a weak acid in water, you must have the Ka value. List two places in this text that provide Ka values for weak acids. You can utilize these tables to help you recognize weak acids. What is the strategy for calculating the pH of a weak acid in water? What assumptions are generally made? What is the 5% rule? If the 5% rule fails, how do you calculate the pH of a weak acid in water?

Two strategies are also followed when solving for the pH of a base in water. What is the strategy for calculating the pH of a strong base in water? List the strong bases mentioned in the text that should be committed to memory. Why is calculating the pH of Ca(OH)2 solutions a little more difficult than calculating the pH of NaOH solutions? Most bases are weak bases. The presence of what element most commonly results in basic properties for an organic compound? What is present on this element in compounds that allows it to accept a proton? Table 14.3 and Appendix 5 of the text list Kb values for some weak bases. What strategy is used to solve for the pH of a weak base in water? What assumptions are made when solving for the pH of weak base solutions? If the 5% rule fails, how do you calculate the pH of a weak base in water?

Table 14.4 lists the stepwise Ka values for some polyprotic acids. What is the difference between a monoprotic acid, a diprotic acid, and a triprotic acid? Most polyprotic acids are weak acids; the major exception is H2SO4. To solve for the pH of a solution of H2SO4, you must generally solve a strong acid problem as well as a weak acid problem. Explain. Write out the reactions that refer to Ka1 and Ka2 for H2SO4. For H3PO4, Ka1 5 7.5 3 1023 , Ka2 5 6.2 3 1028 , and Ka3 5 4.8 3 10213.Write out the reactions that refer to the Ka1 , Ka2 , and Ka3 equilibrium constants. What are the three acids in a solution of H3PO4? Which acid is strongest? What are the three conjugate bases in a solution of H3PO4? Which conjugate base is strongest? Summarize the strategy for calculating the pH of a polyprotic acid in water

For conjugate acidbase pairs, how are Ka and Kb related? Consider the reaction of acetic acid in water CH3CO2H1aq2 1 H2O1l2mCH3CO2 2 1aq2 1 H3O1 1aq2 where Ka 5 1.8 3 1025 . a. Which two bases are competing for the proton? b. Which is the stronger base? c. In light of your answer to part b, why do we classify the acetate ion (CH3CO2 2) as a weak base? Use an appropriate reaction to justify your answer. In general, as base strength increases, conjugate acid strength decreases. Explain why the conjugate acid of the weak base NH3 is a weak acid.To summarize, the conjugate base of a weak acid is a weak base and the conjugate acid of a weak base is a weak acid (weak gives you weak). Assuming Ka for a monoprotic strong acid is 1 3 106 , calculate Kb for the conjugate base of this strong acid. Why do conjugate bases of strong acids have no basic properties in water? List the conjugate bases of the six common strong acids. To tie it all together, some instructors have students think of Li1, K1, Rb1, Cs1, Ca21, Sr21, and Ba21 as the conjugate acids of the strong bases LiOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. Although not technically correct, the conjugate acid strength of these cations is similar to the conjugate base strength of the strong acids. That is, these cations have no acidic properties in water; similarly, the conjugate bases of strong acids have no basic properties (strong gives you worthless). Fill in the blanks with the correct response. The conjugate base of a weak acid is a base. The conjugate acid of a weak base is a acid. The conjugate base of a strong acid is a base. The conjugate acid of a strong base is a acid. (Hint: Weak gives you weak and strong gives you worthless.)

What is a salt? List some anions that behave as weak bases in water. List some anions that have no basic properties in water. List some cations that behave as weak acids in water. List some cations that have no acidic properties in water. Using these lists, give some formulas for salts that have only weak base properties in water. What strategy would you use to solve for the pH of these basic salt solutions? Identify some salts that have only weak acid properties in water. What strategy would you use to solve for the pH of these acidic salt solutions? Identify some salts that have no acidic or basic properties in water (produce neutral solutions). When a salt contains both a weak acid ion and a weak base ion, how do you predict whether the solution pH is acidic, basic, or neutral?

For oxyacids, how does acid strength depend on a. the strength of the bond to the acidic hydrogen atom? b. the electronegativity of the element bonded to the oxygen atom that bears the acidic hydrogen? c. the number of oxygen atoms? How does the strength of a conjugate base depend on these factors? What type of solution forms when a nonmetal oxide dissolves in water? Give an example of such an oxide. What type of solution forms when a metal oxide dissolves in water? Give an example of such an oxide.

Consider two beakers of pure water at different temperatures. How do their pH values compare? Which is more acidic? more basic? Explain

Differentiate between the terms strength and concentration as they apply to acids and bases. When is HCl strong? Weak? Concentrated? Dilute? Answer the same questions for ammonia. Is the conjugate base of a weak acid a strong base?

Sketch two graphs: (a) percent dissociation for weak acid HA versus the initial concentration of HA ([HA]0) and (b) H1 concentration versus [HA]0. Explain both

Consider a solution prepared by mixing a weak acid HA and HCl. What are the major species? Explain what is occurring in solution. How would you calculate the pH? What if you added NaA to this solution? Then added NaOH?

Explain why salts can be acidic, basic, or neutral, and show examples. Do this without specific numbers.

Consider two separate aqueous solutions: one of a weak acid HA and one of HCl. Assuming you started with 10 molecules of each: a. Draw a picture of what each solution looks like at equilibrium. b. What are the major species in each beaker? c. From your pictures, calculate the Ka values of each acid. d. Order the following from the strongest to the weakest base: H2O, A2, Cl2. Explain your order.

You are asked to calculate the H1 concentration in a solution of NaOH(aq). Because sodium hydroxide is a base, can we say there is no H1, since having H1 would imply that the solution is acidic?

Consider a solution prepared by mixing a weak acid HA, HCl, and NaA. Which of the following statements best describes what happens? a. The H1 from the HCl reacts completely with the A2 from the NaA. Then the HA dissociates somewhat. b. The H1 from the HCl reacts somewhat with the A2 from the NaA to make HA, while the HA is dissociating. Eventually you have equal amounts of everything. c. The H1 from the HCl reacts somewhat with the A2 from the NaA to make HA while the HA is dissociating. Eventually all the reactions have equal rates. d. The H1 from the HCl reacts completely with the A2 from the NaA. Then the HA dissociates somewhat until too much H1 and A2 are formed, so the H1 and A2 react to form HA, and so on. Eventually equilibrium is reached. Justify your choice, and for choices you did not pick, explain what is wrong with them

Consider a solution formed by mixing 100.0 mL of 0.10 M HA (Ka 5 1.0 3 1026 ), 100.00 mL of 0.10 M NaA, and 100.0 mL of 0.10 M HCl. In calculating the pH for the final solution, you would make some assumptions about the order in which various reactions occur to simplify the calculations. State these assumptions. Does it matter whether the reactions actually occur in the assumed order? Explain.

A certain sodium compound is dissolved in water to liberate Na1 ions and a certain negative ion. What evidence would you look for to determine whether the anion is behaving as an acid or a base? How could you tell whether the anion is a strong base? Explain how the anion could behave simultaneously as an acid and a base.

Acids and bases can be thought of as chemical opposites (acids are proton donors, and bases are proton acceptors). Therefore, one might think that Ka 5 1yKb. Why isnt this the case? What is the relationship between Ka and Kb? Prove it with a derivation

Consider two solutions of the salts NaX(aq) and NaY(aq) at equal concentrations. What would you need to know to determine which solution has the higher pH? Explain how you would decide (perhaps even provide a sample calculation).

What is meant by pH? True or false: A strong acid solution always has a lower pH than a weak acid solution. Explain.

Why is the pH of water at 258C equal to 7.00?

Can the pH of a solution be negative? Explain.

Is the conjugate base of a weak acid a strong base? Explain. Explain why Cl2 does not affect the pH of an aqueous solution

Match the following pH values: 1, 2, 5, 6, 6.5, 8, 11, 11, and 13 with the following chemicals (of equal concentration): HBr, NaOH, NaF, NaCN, NH4F, CH3NH3F, HF, HCN, and NH3. Answer this question without performing calculations

The salt BX, when dissolved in water, produces an acidic solution. Which of the following could be true? (There may be more than one correct answer.) a. The acid HX is a weak acid. b. The acid HX is a strong acid. c. The cation B1 is a weak acid. Explain

Anions containing hydrogen (for example, HCO3 2 and H2PO4 2) usually show amphoteric behavior. Write equations illustrating the amphoterism of these two anions.

Which of the following conditions indicate an acidic solution at 258C? a. pH 5 3.04 b. [H1] . 1.0 3 1027 M c. pOH 5 4.51 d. [OH2] 5 3.21 3 10212 M

Which of the following conditions indicate a basic solution at 258C? a. pOH 5 11.21 b. pH 5 9.42 c. [OH2] . [H1] d. [OH2] . 1.0 3 1027 M

Why is H3O1 the strongest acid and OH2 the strongest base that can exist in significant amounts in aqueous solutions?

How many significant figures are there in the following numbers: 10.78, 6.78, 0.78? If these were pH values, to how many significant figures can you express the [H1]? Explain any discrepancies between your answers to the two questions.

In terms of orbitals and electron arrangements, what must be present for a molecule or an ion to act as a Lewis acid? What must be present for a molecule or an ion to act as a Lewis base?

Consider the autoionization of liquid ammonia: + + + Label each of the species in the equation as an acid or a base and explain your answer

The following are representations of acidbase reactions: + + + + + + a. Label each of the species in both equations as an acid or a base and explain your answers. b. For those species that are acids, which labels apply: Arrhenius acid, BrnstedLowry acid, Lewis acid? What about the bases?

Give three example solutions that fit each of the following descriptions. a. a strong electrolyte solution that is very acidic b. a strong electrolyte solution that is slightly acidic c. a strong electrolyte solution that is very basic d. a strong electrolyte solution that is slightly basic e. a strong electrolyte solution that is neutral

Derive an expression for the relationship between pKa and pKb for a conjugate acidbase pair. (pK 5 2log K.)

Consider the following statements. Write out an example reaction and K expression that is associated with each statement. a. The autoionization of water. b. An acid reacts with water to produce the conjugate base of the acid and the hydronium ion. c. A base reacts with water to produce the conjugate acid of the base and the hydroxide ion

Which of the following statements is(are) true? Correct the false statements. a. When a base is dissolved in water, the lowest possible pH of the solution is 7.0. b. When an acid is dissolved in water, the lowest possible pH is 0. c. A strong acid solution will have a lower pH than a weak acid solution.d. A 0.0010-M Ba(OH)2 solution has a pOH that is twice the pOH value of a 0.0010-M KOH solution

Consider the following mathematical expressions. a. [H1] 5 [HA]0 b. [H1] 5 (Ka 3 [HA]0)1y2 c. [OH2] 5 2[B]0 d. [OH2] 5 (Kb 3 [B]0)1y2 For each expression, give three solutions where the mathematical expression would give a good approximation for the [H1] or [OH2]. [HA]0 and [B]0 represent initial concentrations of an acid or a base

Consider a 0.10-M H2CO3 solution and a 0.10-M H2SO4 solution. Without doing any detailed calculations, choose one of the following statements that best describes the [H1] of each solution and explain your answer. a. The [H1] is less than 0.10 M. b. The [H1] is 0.10 M. c. The [H1] is between 0.10 M and 0.20 M. d. The [H1] is 0.20 M

Of the hydrogen halides, only HF is a weak acid. Give a possible explanation.

Explain why the following are done, both of which are related to acidbase chemistry. a. Power plants burning coal with high sulfur content use scrubbers to help eliminate sulfur emissions. b. A gardener mixes lime (CaO) into the soil of his garden

Write balanced equations that describe the following reactions. a. the dissociation of perchloric acid in water b. the dissociation of propanoic acid (CH3CH2CO2H) in water c. the dissociation of ammonium ion in water

Write the dissociation reaction and the corresponding Ka equilibrium expression for each of the following acids in water. a. HCN b. HOC6H5 c. C6H5NH3 1

For each of the following aqueous reactions, identify the acid, the base, the conjugate base, and the conjugate acid. a. H2O 1 H2CO3mH3O1 1 HCO3 2 b. C5H5NH1 1 H2OmC5H5N 1 H3O1 c. HCO3 2 1 C5H5NH1mH2CO3 1 C5H5N

For each of the following aqueous reactions, identify the acid, the base, the conjugate base, and the conjugate acid. a. Al1H2O2 6 31 1 H2OmH3O1 1 Al1H2O2 5 1OH2 21 b. H2O 1 HONH3 1mHONH2 1 H3O1 c. HOCl 1 C6H5NH2mOCl2 1 C6H5NH3 1

Classify each of the following as a strong acid or a weak acid. c. d. Cl S O H

Consider the following illustrations: H+ A B Which beaker best illustrates what happens when the following acids are dissolved in water? a. HNO2 d. HF b. HNO3 e. HC2H3O2 c. HCl

Use Table 14.2 to order the following from the strongest to the weakest acid. HClO2, H2O, NH4 1, HClO4

Use Table 14.2 to order the following from the strongest to the weakest base. ClO2 2, H2O, NH3, ClO4

You may need Table 14.2 to answer the following questions. a. Which is the stronger acid, HCl or H2O? b. Which is the stronger acid, H2O or HNO2? c. Which is the stronger acid, HCN or HOC6H5?

You may need Table 14.2 to answer the following questions. a. Which is the stronger base, Cl2 or H2O? b. Which is the stronger base, H2O or NO2 2? c. Which is the stronger base, CN2or OC6H5 2?

Calculate the [OH2] of each of the following solutions at 258C. Identify each solution as neutral, acidic, or basic. a. [H1] 5 1.0 3 1027 M c. [H1] 5 12 M b. [H1] 5 8.3 3 10216 M d. [H1] 5 5.4 3 1025 M

Calculate the [H1] of each of the following solutions at 258C. Identify each solution as neutral, acidic, or basic. a. [OH2] 5 1.5 M b. [OH2] 5 3.6 3 10215 M c. [OH2] 5 1.0 3 1027 M d. [OH2] 5 7.3 3 1024 M

Values of Kw as a function of temperature are as follows: Temperature (8C) Kw 0 1.14 3 10215 25 1.00 3 10214 35 2.09 3 10214 40. 2.92 3 10214 50. 5.47 3 10214 a. Is the autoionization of water exothermic or endothermic? b. Calculate [H1] and [OH2] in a neutral solution at 50.8C.

At 40.8C the value of Kw is 2.92 3 10214. a. Calculate the [H1] and [OH2] in pure water at 40.8C. b. What is the pH of pure water at 40.8C? c. If the hydroxide ion concentration in a solution is 0.10 M, what is the pH at 40.8C?

Calculate the pH and pOH of the solutions in Exercises 45 and 46.

Calculate [H1] and [OH2] for each solution at 258C. Identify each solution as neutral, acidic, or basic. a. pH 5 7.40 (the normal pH of blood) b. pH 5 15.3 c. pH 5 21.0 d. pH 5 3.20 e. pOH 5 5.0 f. pOH 5 9.60

Fill in the missing information in the following table. pH pOH [H1] [OH2] Acidic, Basic, or Neutral? Solution a 6.88 Solution b 8.4 3 10214 M Solution c 3.11 Solution d 1.0 3 1027 M 52. Fill in the missing information in the following table. pH pOH [H1] [OH2] Acidic, Basic, or Neutral? Solution a 9.63 Solution b 3.9 3 1026 M Solution c 0.027 M Solution d 1.22

The pH of a sample of gastric juice in a persons stomach is 2.1. Calculate the pOH, [H1], and [OH2] for this sample. Is gastric juice acidic or basic?

The pOH of a sample of baking soda dissolved in water is 5.74 at 258C. Calculate the pH, [H1], and [OH2] for this sample. Is the solution acidic or basic?

What are the major species present in 0.250 M solutions of each of the following acids? Calculate the pH of each of these solutions. a. HClO4 b. HNO

A solution is prepared by adding 50.0 mL of 0.050 M HBr to 150.0 mL of 0.10 M HI. Calculate [H1] and the pH of this solution. HBr and HI are both considered strong acids.

Calculate the pH of each of the following solutions of a strong acid in water. a. 0.10 M HCl c. 1.0 3 10211 M HCl b. 5.0 M HCl

Calculate the pH of each of the following solutions containing a strong acid in water. a. 2.0 3 1022 M HNO3 c. 6.2 3 10212 M HNO3 b. 4.0 M HNO3

Calculate the concentration of an aqueous HI solution that has pH 5 2.50. HI is a strong acid.

Calculate the concentration of an aqueous HBr solution that has pH 5 4.25. HBr is a strong acid

How would you prepare 1600 mL of a pH 5 1.50 solution using concentrated (12 M) HCl?

A solution is prepared by adding 50.0 mL concentrated hydrochloric acid and 20.0 mL concentrated nitric acid to 300 mL water. More water is added until the final volume is 1.00 L. Calculate [H1], [OH2], and the pH for this solution. [Hint: Concentrated HCl is 38% HCl (by mass) and has a density of 1.19 g/mL; concentrated HNO3 is 70.% HNO3 (by mass) and has a density of 1.42 g/mL.]

What are the major species present in 0.250 M solutions of each of the following acids? Calculate the pH of each of these solutions. a. HNO2 b. CH3CO2H (HC2H3O2

What are the major species present in 0.250 M solutions of each of the following acids? Calculate the pH of each of these solutions. a. HOC6H5 b. HCN

Calculate the concentration of all species present and the pH of a 0.020-M HF solution.

Calculate the percent dissociation for a 0.22-M solution of chlorous acid (HClO2, Ka 5 1.2 3 1022 ).

For propanoic acid (HC3H5O2, Ka 5 1.3 3 1025 ), determine the concentration of all species present, the pH, and the percent dissociation of a 0.100-M solution

A solution is prepared by dissolving 0.56 g benzoic acid (C6H5CO2H, Ka 5 6.4 3 1025 ) in enough water to make 1.0 L of solution. Calculate [C6H5CO2H], [C6H5CO2 2], [H1], [OH2], and the pH of this solution.

Monochloroacetic acid, HC2H2ClO2, is a skin irritant that is used in chemical peels intended to remove the top layer of dead skin from the face and ultimately improve the complexion. The value of Ka for monochloroacetic acid is 1.35 3 1023 . Calculate the pH of a 0.10-M solution of monochloroacetic acid.

A typical aspirin tablet contains 325 mg acetylsalicylic acid (HC9H7O4). Calculate the pH of a solution that is prepared by dissolving two aspirin tablets in enough water to make one cup (237 mL) of solution. Assume the aspirin tablets are pure acetylsalicylic acid, Ka 5 3.3 3 1024

Calculate the pH of a solution that contains 1.0 M HF and 1.0 M HOC6H5. Also calculate the concentration of OC6H5 2 in this solution at equilibrium

A solution is made by adding 50.0 mL of 0.200 M acetic acid (Ka 5 1.8 3 1025 ) to 50.0 mL of 1.00 3 1023 M HCl. a. Calculate the pH of the solution. b. Calculate the acetate ion concentration.

Calculate the percent dissociation of the acid in each of the following solutions. a. 0.50 M acetic acid b. 0.050 M acetic acid c. 0.0050 M acetic acid d. Use Le Chteliers principle to explain why percent dissociation increases as the concentration of a weak acid decreases. e. Even though the percent dissociation increases from solutions a to c, the [H1] decreases. Explain

Using the Ka values in Table 14.2, calculate the percent dissociation in a 0.20-M solution of each of the following acids. a. nitric acid (HNO3) b. nitrous acid (HNO2) c. phenol (HOC6H5) d. How is percent dissociation of an acid related to the Ka value for the acid (assuming equal initial concentrations of acids)?

A 0.15-M solution of a weak acid is 3.0% dissociated. Calculate Ka.

An acid HX is 25% dissociated in water. If the equilibrium concentration of HX is 0.30 M, calculate the Ka value for HX

Trichloroacetic acid (CCl3CO2H) is a corrosive acid that is used to precipitate proteins. The pH of a 0.050-M solution of trichloroacetic acid is the same as the pH of a 0.040-M HClO4 solution. Calculate Ka for trichloroacetic acid

The pH of a 0.063-M solution of hypobromous acid (HOBr but usually written HBrO) is 4.95. Calculate K

A solution of formic acid (HCOOH, Ka 5 1.8 3 1024 ) has a pH of 2.70. Calculate the initial concentration of formic acid in this solution.

A typical sample of vinegar has a pH of 3.0. Assuming that vinegar is only an aqueous solution of acetic acid (Ka 5 1.8 3 1025 ), calculate the concentration of acetic acid in vinegar

One mole of a weak acid HA was dissolved in 2.0 L of solution. After the system had come to equilibrium, the concentration of HA was found to be 0.45 M. Calculate Ka for HA.

You have 100.0 g saccharin, a sugar substitute, and you want to prepare a pH 5 5.75 solution. What volume of solution can be prepared? For saccharin, HC7H4NSO3, pKa 5 11.70 (pKa 5 2log Ka).

Write the reaction and the corresponding Kb equilibrium expression for each of the following substances acting as bases in water. a. NH3 b. C5H5N

Write the reaction and the corresponding Kb equilibrium expression for each of the following substances acting as bases in water. a. aniline, C6H5NH2 b. dimethylamine, (CH3)2NH

Use Table 14.3 to help order the following bases from strongest to weakest. NO3 2, H2O, NH3, C5H5N

Use Table 14.3 to help order the following acids from strongest to weakest. HNO3, H2O, NH4 1, C5H5NH1

Use Table 14.3 to help answer the following questions. a. Which is the stronger base, ClO4 2 or C6H5NH2? b. Which is the stronger base, H2O or C6H5NH2? c. Which is the stronger base, OH2or C6H5NH2? d. Which is the stronger base, C6H5NH2 or CH3NH2?

Use Table 14.3 to help answer the following questions. a. Which is the stronger acid, HClO4 or C6H5NH3 1? b. Which is the stronger acid, H2O or C6H5NH3 1? c. Which is the stronger acid, C6H5NH3 1 or CH3NH3 1?

Calculate the pH of the following solutions. a. 0.10 M NaOH b. 1.0 3 10210 M NaOH c. 2.0 M NaOH

Calculate [OH2], pOH, and pH for each of the following. a. 0.00040 M Ca(OH)2 b. a solution containing 25 g KOH per liter c. a solution containing 150.0 g NaOH per liter

What are the major species present in 0.015 M solutions of each of the following bases? a. KOH b. Ba(OH)2 What is [OH2] and the pH of each of these solutions?

What are the major species present in the following mixtures of bases? a. 0.050 M NaOH and 0.050 M LiOH b. 0.0010 M Ca(OH)2 and 0.020 M RbOH What is [OH2] and the pH of each of these solutions?

What mass of KOH is necessary to prepare 800.0 mL of a solution having a pH 5 11.56?

Calculate the concentration of an aqueous Sr(OH)2 that has pH 510.50.

What are the major species present in a 0.150-M NH3 solution? Calculate the [OH2] and the pH of this solution.

For the reaction of hydrazine (N2H4) in water, H2NNH2 1aq2 1 H2O1l2mH2NNH3 1 1aq2 1 OH2 1aq2 Kb is 3.0 3 1026 . Calculate the concentrations of all species and the pH of a 2.0-M solution of hydrazine in water.

Calculate [OH2], [H1], and the pH of 0.20 M solutions of each of the following amines. a. triethylamine [(C2H5)3N, Kb 5 4.0 3 1024 ] b. hydroxylamine (HONH2, Kb 5 1.1 3 1028 )

Calculate [OH2], [H1], and the pH of 0.40 M solutions of each of the following amines (the Kb values are found in Table 14.3). a. aniline b. methylamine

Calculate the pH of a 0.20-M C2H5NH2 solution (Kb 5 5.6 3 1024 ).

Calculate the pH of a 0.050-M (C2H5)2NH solution (Kb 5 1.3 3 1023).

What is the percent ionization in each of the following solutions? a. 0.10 M NH3 c. 0.10 M CH3NH2 b. 0.010 M NH

Calculate the percentage of pyridine (C5H5N) that forms pyridinium ion, C5H5NH1, in a 0.10-M aqueous solution of pyridine (Kb 5 1.7 3 1029 )

The pH of a 0.016-M aqueous solution of p-toluidine (CH3C6H4NH2) is 8.60. Calculate Kb.

Calculate the mass of HONH2 required to dissolve in enough water to make 250.0 mL of solution having a pH of 10.00 (Kb 5 1.1 3 1028 ).

Write out the stepwise Ka reactions for the diprotic acid H2SO3

Write out the stepwise Ka reactions for citric acid (H3C6H5O7), a triprotic acid.

A typical vitamin C tablet (containing pure ascorbic acid, H2C6H6O6) weighs 500. mg. One vitamin C tablet is dissolved in enough water to make 200.0 mL of solution. Calculate the pH of this solution. Ascorbic acid is a diprotic acid.

Arsenic acid (H3AsO4) is a triprotic acid with Ka1 5 5.5 3 1023 , Ka2 5 1.7 3 1027 , and Ka3 5 5.1 3 10212. Calculate [H1], [OH2], [H3AsO4], [H2AsO4 2], [HAsO4 22], and [AsO4 32] in a 0.20-M arsenic acid solution

Calculate the pH and [S22] in a 0.10-M H2S solution. Assume Ka1 5 1.0 3 1027 ; Ka2 5 1.0 3 10219.

Calculate [CO3 22] in a 0.010-M solution of CO2 in water (usually written as H2CO3). If all the CO3 22 in this solution comes from the reaction HCO3 2 1aq2mH1 1aq2 1 CO3 22 1aq2 what percentage of the H1 ions in the solution is a result of the dissociation of HCO3 2? When acid is added to a solution of sodium hydrogen carbonate (NaHCO3), vigorous bubbling occurs. How is this reaction related to the existence of carbonic acid (H2CO3) molecules in aqueous solution?

Calculate the pH of a 2.0-M H2SO4 solution.

Calculate the pH of a 5.0 3 1023 -M solution of H2SO4.

Arrange the following 0.10 M solutions in order of most acidic to most basic. KOH, KNO3, KCN, NH4Cl, HCl

Arrange the following 0.10 M solutions in order from most acidic to most basic. See Appendix 5 for Ka and Kb values. CaBr2, KNO2, HClO4, HNO2, HONH3ClO4

Given that the Ka value for acetic acid is 1.8 3 1025 and the Ka value for hypochlorous acid is 3.5 3 1028 , which is the stronger base, OCl2 or C2H3O2 2?

The Kb values for ammonia and methylamine are 1.8 3 1025 and 4.4 3 1024 , respectively. Which is the stronger acid, NH4 1 or CH3NH3 1?

Determine [OH2], [H1], and the pH of each of the following solutions. a. 1.0 M KCl b. 1.0 M KC2H3O2

Calculate the concentrations of all species present in a 0.25-M solution of ethylammonium chloride (C2H5NH3Cl).

Calculate the pH of each of the following solutions. a. 0.10 M CH3NH3Cl b. 0.050 M NaCN

Calculate the pH of each of the following solutions. a. 0.12 M KNO2 c. 0.40 M NH4ClO4 b. 0.45 M NaOCl

Sodium azide (NaN3) is sometimes added to water to kill bacteria. Calculate the concentration of all species in a 0.010-M solution of NaN3. The Ka value for hydrazoic acid (HN3) is 1.9 3 1025 .

Papaverine hydrochloride (abbreviated papH1Cl2; molar mass 5 378.85 g/mol) is a drug that belongs to a group of medicines called vasodilators, which cause blood vessels to expand, thereby increasing blood flow. This drug is the conjugate acid of the weak base papaverine (abbreviated pap; Kb 5 8.33 3 1029 at 35.08C). Calculate the pH of a 30.0-mg/mL aqueous dose of papH1Cl2 prepared at 35.08C. Kw at 35.08C is 2.1 3 10214

An unknown salt is either NaCN, NaC2H3O2, NaF, NaCl, or NaOCl. When 0.100 mole of the salt is dissolved in 1.00 L of solution, the pH of the solution is 8.07. What is the identity of the salt?

Consider a solution of an unknown salt having the general formula BHCl, where B is one of the weak bases in Table 14.3. A 0.10-M solution of the unknown salt has a pH of 5.82. What is the actual formula of the salt?

A 0.050-M solution of the salt NaB has a pH of 9.00. Calculate the pH of a 0.010-M solution of HB

A 0.20-M sodium chlorobenzoate (NaC7H4ClO2) solution has a pH of 8.65. Calculate the pH of a 0.20-M chlorobenzoic acid (HC7H4ClO2) solution

Calculate the pH of a 0.050-M Al(NO3)3 solution. The Ka value for Al(H2O)6 31 is 1.4 3 1025 .

Calculate the pH of a 0.10-M CoCl3 solution. The Ka value for Co(H2O)6 31 is 1.0 3 1025 .

Are solutions of the following salts acidic, basic, or neutral? For those that are not neutral, write balanced chemical equations for the reactions causing the solution to be acidic or basic. The relevant Ka and Kb values are found in Tables 14.2 and 14.3. a. NaNO3 c. C5H5NHClO4 e. KOCl b. NaNO2 d. NH4NO2 f. NH4OCl

Are solutions of the following salts acidic, basic, or neutral? For those that are not neutral, write balanced equations for the reactions causing the solution to be acidic or basic. The relevant Ka and Kb values are found in Tables 14.2 and 14.3. a. Sr(NO3)2 c. CH3NH3Cl e. NH4F b. NH4C2H3O2 d. C6H5NH3ClO2 f. CH3NH3CN

Place the species in each of the following groups in order of increasing acid strength. Explain the order you chose for each group. a. HIO3, HBrO3 c. HOCl, HOI b. HNO2, HNO3 d. H3PO4, H3PO3

Place the species in each of the following groups in order of increasing base strength. Give your reasoning in each case. a. IO3 2, BrO3 2 b. NO2 2, NO3 2 c. OCl2, OI2

Place the species in each of the following groups in order of increasing acid strength. a. H2O, H2S, H2Se (bond energies: HOO, 467 kJ/mol; HOS, 363 kJ/mol; HOSe, 276 kJ/mol) b. CH3CO2H, FCH2CO2H, F2CHCO2H, F3CCO2H c. NH4 1, HONH3 1 d. NH4 1, PH4 1 (bond energies: NOH, 391 kJ/mol; POH, 322 kJ/mol) Give reasons for the orders you chose.

Using your results from Exercise 133, place the species in each of the following groups in order of increasing base strength. a. OH2, SH2, SeH2 b. NH3, PH3 c. NH3, HONH2

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers. a. CaO b. SO2 c. Cl2O

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers. a. Li2O b. CO2 c. SrO

Identify the Lewis acid and the Lewis base in each of the following reactions. a. B1OH2 3 1aq2 1 H2O1l2mB1OH2 4 2 1aq2 1 H1 1aq2 b. Ag1 1aq2 1 2NH3 1aq2mAg1NH32 2 1 1aq2 c. BF3 1g2 1 F2 1aq2mBF4 2 1aq2

Identify the Lewis acid and the Lewis base in each of the following reactions. a. Fe31 1aq2 1 6H2O1l2mFe1H2O2 6 31 1aq2 b. H2O1l2 1 CN2 1aq2mHCN1aq2 1 OH2 1aq2 c. HgI2 1s2 1 2I2 1aq2mHgI4 22 1aq2

Aluminum hydroxide is an amphoteric substance. It can act as either a BrnstedLowry base or a Lewis acid. Write a reaction showing Al(OH)3 acting as a base toward H1 and as an acid toward OH2

Zinc hydroxide is an amphoteric substance. Write equations that describe Zn(OH)2 acting as a BrnstedLowry base toward H1 and as a Lewis acid toward OH2.

Would you expect Fe31 or Fe21 to be the stronger Lewis acid? Explain

Use the Lewis acidbase model to explain the following reaction. CO2 1g2 1 H2O1l2 h H2CO3 1aq2

A 10.0-mL sample of an HCl solution has a pH of 2.000. What volume of water must be added to change the pH to 4.000?

Which of the following represent conjugate acidbase pairs? For those pairs that are not conjugates, write the correct conjugate acid or base for each species in the pair. a. H2O, OH2 c. H3PO4, H2PO4 2 b. H2SO4, SO4 22 d. HC2H3O2, C2H3O2 2

A solution is tested for pH and conductivity as pictured below: The solution contains one of the following substances: HCl, NaOH, NH4Cl, HCN, NH3, HF, or NaCN. If the solute concentration is about 1.0 M, what is the identity of the solute?

The pH of human blood is steady at a value of approximately 7.4 owing to the following equilibrium reactions: CO2 1aq2 1 H2O1l2mH2CO3 1aq2mHCO3 2 1aq2 1 H1 1aq2 Acids formed during normal cellular respiration react with the HCO3 2 to form carbonic acid, which is in equilibrium with CO2(aq) and H2O(l). During vigorous exercise, a persons H2CO3 blood levels were 26.3 mM, whereas his CO2 level were 1.63 mM. On resting, the H2CO3 levels declined to 24.9 mM. What was the CO2 blood level at rest?

Hemoglobin (abbreviated Hb) is a protein that is responsible for the transport of oxygen in the blood of mammals. Each hemoglobin molecule contains four iron atoms that are the binding sites for O2 molecules. The oxygen binding is pHdependent. The relevant equilibrium reaction is HbH4 41 1aq2 1 4O2 1g2mHb1O22 4 1aq2 1 4H1 1aq2 Use Le Chteliers principle to answer the following. a. What form of hemoglobin, HbH4 41 or Hb(O2)4, is favored in the lungs? What form is favored in the cells? b. When a person hyperventilates, the concentration of CO2 in the blood is decreased. How does this affect the oxygenbinding equilibrium? How does breathing into a paper bag help to counteract this effect? (See Exercise 146.) c. When a person has suffered a cardiac arrest, injection of a sodium bicarbonate solution is given. Why is this necessary? (Hint: CO2 blood levels increase during cardiac arrest.)

A 0.25-g sample of lime (CaO) is dissolved in enough water to make 1500 mL of solution. Calculate the pH of the solution.

At 258C, a saturated solution of benzoic acid (Ka 5 6.4 3 1025 ) has a pH of 2.80. Calculate the water solubility of benzoic acid in moles per liter.

Calculate the pH of an aqueous solution containing 1.0 3 1022 M HCl, 1.0 3 1022 M H2SO4, and 1.0 3 1022 M HCN

Acrylic acid 1CH2wCHCO2H2 is a precursor for many important plastics. Ka for acrylic acid is 5.6 3 1025 . a. Calculate the pH of a 0.10-M solution of acrylic acid. b. Calculate the percent dissociation of a 0.10-M solution of acrylic acid. c. Calculate the pH of a 0.050-M solution of sodium acrylate (NaC3H3O2).

Classify each of the following as a strong acid, weak acid, strong base, or weak base in aqueous solution. a. HNO2 b. HNO3 c. CH3NH2 g. O OHHC d. NaOH h. Ca(OH)2 e. NH3 i. H2SO4 f. HF

The following illustration displays the relative number of species when an acid, HA, is added to water.a. Is HA a weak or strong acid? How can you tell? b. Using the relative numbers given in the illustration, determine the value for Ka and the percent dissociation of the acid. Assume the initial acid concentration is 0.20 M

Quinine (C20H24N2O2) is the most important alkaloid derived from cinchona bark. It is used as an antimalarial drug. For quinine, pKb1 5 5.1 and pKb2 5 9.7 (pKb 5 2log Kb). Only 1 g quinine will dissolve in 1900.0 mL of solution. Calculate the pH of a saturated aqueous solution of quinine. Consider only the reaction Q 1 H2OmQH1 1 OH2 described by pKb1 , where Q 5 quinine

Codeine (C18H21NO3) is a derivative of morphine that is used as an analgesic, narcotic, or antitussive. It was once commonly used in cough syrups but is now available only by prescription because of its addictive properties. If the pH of a 1.7 3 1023 -M solution of codeine is 9.59, calculate Kb

A codeine-containing cough syrup lists codeine sulfate as a major ingredient instead of codeine. The Merck Index gives C36H44N2O10S as the formula for codeine sulfate. Describe the composition of codeine sulfate. (See Exercise 155.) Why is codeine sulfate used instead of codeine?

The equilibrium constant Ka for the reaction Fe1H2O2 6 31 1aq2 1 H2O1l2m Fe1H2O2 5 1OH2 21 1aq2 1 H3O1 1aq2 is 6.0 3 1023 . a. Calculate the pH of a 0.10-M solution of Fe(H2O)6 31. b. Will a 1.0-M solution of iron(II) nitrate have a higher or lower pH than a 1.0-M solution of iron(III) nitrate? Explain.

Rank the following 0.10 M solutions in order of increasing pH. a. HI, HF, NaF, NaI b. NH4Br, HBr, KBr, NH3 c. C6H5NH3NO3, NaNO3, NaOH, HOC6H5, KOC6H5, C6H5NH2, HNO3

Is an aqueous solution of NaHSO4 acidic, basic, or neutral? What reaction occurs with water? Calculate the pH of a 0.10-M solution of NaHSO4

Calculate the value for the equilibrium constant for each of the following aqueous reactions. a. NH3 1 H3O1mNH4 1 1 H2O b. NO2 2 1 H3O1mHNO2 1 H2O c. NH4 1 1 OH2mNH3 1 H2O d. HNO2 1 OH2mH2O 1 NO2 2

Students are often surprised to learn that organic acids, such as acetic acid, contain OOH groups. Actually, all oxyacids contain hydroxyl groups. Sulfuric acid, usually written as H2SO4, has the structural formula SO2(OH)2, where S is the central atom. Identify the acids whose structural formulas are shown below. Why do they behave as acids, while NaOH and KOH are bases? a. SO(OH)2 b. ClO2(OH) c. HPO(OH)2

For solutions of the same concentration, as acid strength increases, indicate what happens to each of the following (increases, decreases, or doesnt change). a. [H1] d. pOH b. pH e. Ka c. [OH2]

Complete the table for each of the following solutions: [H1] pH pOH [OH2] 0.0070 M HNO3 3.0 M KOH

Consider a 0.60-M solution of HC3H5O3, lactic acid (Ka 5 1.4 3 1024 ). a. Which of the following are major species in the solution? i. HC3H5O3 ii. C3H5O3 2 iii. H1 iv. H2O v. OH2 b. Complete the following ICE table in terms of x, the amount (mol/L) of lactic acid that dissociates to reach equilibrium. [HC3H5O3] [H1] [C3H5O3 2] Initial Change Equilibrium 0.60 2 x c. What is the equilibrium concentration for C3H5O3 2? d. Calculate the pH of the solution

Consider a 0.67-M solution of C2H5NH2 (Kb 5 5.6 3 1024 ). a. Which of the following are major species in the solution? i. C2H5NH2 ii. H1 iii. OH2 iv. H2O v. C2H5NH3 1 b. Calculate the pH of this solution

Rank the following 0.10 M solutions in order of increasing pH. a. NH3 d. KCl b. KOH e. HCl c. HC2H3O

Consider 0.25 M solutions of the following salts: NaCl, RbOCl, KI, Ba(ClO4)2, and NH4NO3. For each salt, indicate whether the solution is acidic, basic, or neutral.

Calculate the pH of the following solutions: a. 1.2 M CaBr2 b. 0.84 M C6H5NH3NO3 (Kb for C6H5NH2 5 3.8 3 10210) c. 0.57 M KC7H5O2 (Ka for HC7H5O2 5 6.4 3 1025

Consider 0.10 M solutions of the following compounds: AlCl3, NaCN, KOH, CsClO4, and NaF. Place these solutions in order of increasing pH.

The pH of 1.0 3 1028 M hydrochloric acid is not 8.00. The correct pH can be calculated by considering the relationship between the molarities of the three principal ions in the solution (H1, Cl2, and OH2). These molarities can be calculated from algebraic equations that can be derived from the considerations given below. a. The solution is electrically neutral. b. The hydrochloric acid can be assumed to be 100% ionized. c. The product of the molarities of the hydronium ions and the hydroxide ions must equal Kw. Calculate the pH of a 1.0 3 1028 -M HCl solution

Calculate the pH of a 1.0 3 1027 -M solution of NaOH in water

Calculate [OH2] in a 3.0 3 1027 -M solution of Ca(OH)2.

Consider 50.0 mL of a solution of weak acid HA (Ka 5 1.00 3 1026 ), which has a pH of 4.000. What volume of water must be added to make the pH 5 5.000?

Making use of the assumptions we ordinarily make in calculating the pH of an aqueous solution of a weak acid, calculate the pH of a 1.0 3 1026 -M solution of hypobromous acid (HBrO, Ka 5 2 3 1029 ). What is wrong with your answer? Why is it wrong? Without trying to solve the problem, explain what has to be included to solve the problem correctly.

Calculate the pH of a 0.200-M solution of C5H5NHF. Hint: C5H5NHF is a salt composed of C5H5NH1 and F2 ions. The principal equilibrium in this solution is the best acid reacting with the best base; the reaction for the principal equilibrium is C5H5NH1 1aq2 1 F2 1aq2m C5H5N1aq2 1 HF1aq2 K 5 8.2 3 1023

Determine the pH of a 0.50-M solution of NH4OCl. (See Exercise 175.)

Calculate [OH2] in a solution obtained by adding 0.0100 mol solid NaOH to 1.00 L of 15.0 M NH3

What mass of NaOH(s) must be added to 1.0 L of 0.050 M NH3 to ensure that the percent ionization of NH3 is no greater than 0.0010%? Assume no volume change on addition of NaOH

Consider 1000. mL of a 1.00 3 1024 -M solution of a certain acid HA that has a Ka value equal to 1.00 3 1024 . How much water was added or removed (by evaporation) so that a solution remains in which 25.0% of HA is dissociated at equilibrium? Assume that HA is nonvolatile.

Calculate the mass of sodium hydroxide that must be added to 1.00 L of 1.00-M HC2H3O2 to double the pH of the solution (assume that the added NaOH does not change the volume of the solution).

Consider the species PO4 32, HPO4 22, and H2PO4 2. Each ion can act as a base in water. Determine the Kb value for each of these species. Which species is the strongest base?

Calculate the pH of a 0.10-M solution of sodium phosphate. (See Exercise 181.)

Will 0.10 M solutions of the following salts be acidic, basic, or neutral? See Appendix 5 for Ka values. a. ammonium bicarbonate b. sodium dihydrogen phosphate c. sodium hydrogen phosphate d. ammonium dihydrogen phosphate e. ammonium formate

a. The principal equilibrium in a solution of NaHCO3 is HCO3 2 1aq2 1 HCO3 2 1aq2mH2CO3 1aq2 1 CO3 22 1aq2 Calculate the value of the equilibrium constant for this reaction. b. At equilibrium, what is the relationship between [H2CO3] and [CO3 22]? c. Using the equilibrium H2CO3 1aq2m2H1 1aq2 1 CO3 22 1aq2 derive an expression for the pH of the solution in terms of Ka1 and Ka2 using the result from part b. d. What is the pH of a solution of NaHCO3?

A 0.100-g sample of the weak acid HA (molar mass 5 100.0 g/mol) is dissolved in 500.0 g water. The freezing point of the resulting solution is 20.00568C. Calculate the value of Ka for this acid. Assume molality equals molarity in this solution

A sample containing 0.0500 mole of Fe2(SO4)3 is dissolved in enough water to make 1.00 L of solution. This solution contains hydrated SO4 22 and Fe31 ions. The latter behaves as an acid: Fe1H2O2 6 31 1aq2mFe1H2O2 5OH21 1aq2 1 H1 1aq2 a. Calculate the expected osmotic pressure of this solution at 258C if the above dissociation is negligible. b. The actual osmotic pressure of the solution is 6.73 atm at 258C. Calculate Ka for the dissociation reaction of Fe(H2O)6 31. (To do this calculation, you must assume that none of the ions go through the semipermeable membrane. Actually, this is not a great assumption for the tiny H1 ion.)

A 2.14-g sample of sodium hypoiodite is dissolved in water to make 1.25 L of solution. The solution pH is 11.32. What is Kb for the hypoiodite ion?

Isocyanic acid (HNCO) can be prepared by heating sodium cyanate in the presence of solid oxalic acid according to the equation 2NaOCN1s2 1 H2C2O4 1s2 h 2HNCO1l2 1 Na2C2O4 1s2 Upon isolating pure HNCO(l), an aqueous solution of HNCO can be prepared by dissolving the liquid HNCO in water. What is the pH of a 100.-mL solution of HNCO prepared from the reaction of 10.0 g each of NaOCN and H2C2O4, assuming all of the HNCO produced is dissolved in solution? (Ka of HNCO 5 1.2 3 1024 .)

A certain acid, HA, has a vapor density of 5.11 g/L when in the gas phase at a temperature of 258C and a pressure of 1.00 atm. When 1.50 g of this acid is dissolved in enough water to make 100.0 mL of solution, the pH is found to be 1.80. Calculate Ka for the acid.

An aqueous solution contains a mixture of 0.0500 M HCOOH (Ka 5 1.77 3 1024 ) and 0.150 M CH3CH2COOH (Ka 5 1.34 3 1025 ). Calculate the pH of this solution. Because both acids are of comparable strength, the H1 contribution from both acids must be considered.

For the following, mix equal volumes of one solution from Group I with one solution from Group II to achieve the indicated pH. Calculate the pH of each solution. Group I: 0.20 M NH4Cl, 0.20 M HCl, 0.20 M C6H5NH3Cl, 0.20 M (C2H5)3NHCl Group II: 0.20 M KOI, 0.20 M NaCN, 0.20 M KOCl, 0.20 M NaNO2 a. the solution with the lowest pH b. the solution with the highest pH c. the solution with the pH closest to 7.00