In a 0.20 M solution, a weak acid is 3.0% dissociated. (a)

What is the role of water in the Arrhenius acid-base definition?

What do Arrhenius acids have in common? What do Arrhenius bases have in common? Explain neutralization in terms of the Arrhenius acid-base definition. What data led Arrhenius to propose this idea of neutralization?

Why is the Arrhenius acid-base definition too limited? Give an example for which the Arrhenius definition does not apply.

What do strong and weak mean for acids and bases? Ka values of weak acids vary over more than 10 orders of magnitude. What do the acids have in common that makes them weak

Which of the following are Arrhenius acids? (a) H2O (b) Ca(OH)2 (c) H3PO3 (d) HI

Which of the following are Arrhenius acids? (a) NaHSO4 (b) CH4 (c) NaH (d) H3N

Which of the following are Arrhenius bases? (a) H3AsO4 (b) Ba(OH)2 (c) HClO (d) KOH

Which of the following are Arrhenius bases? (a) CH3COOH (b) HOH (c) CH3OH (d) H2NNH2

Write the Ka expression for each of the following in water: (a) HCN (b) HCO3 ? (c) HCOOH

Write the Ka expression for each of the following in water: (a) CH3NH3 (b) HClO (c) H2S

Write the Ka expression for each of the following in water: (a) HNO2 (b) CH3COOH (c) HBrO2

Write the Ka expression for each of the following in water: (a) H2PO4 ? (b) H3PO2 (c) HSO4

Use Appendix C to rank the following in order of increasing acid strength: HIO3, HI, CH3COOH, HF

Use Appendix C to rank the following in order of decreasing acid strength: HClO, HCl, HCN, HNO2.

Classify each as a strong or weak acid or base: (a) H3AsO4 (b) Sr(OH)2 (c) HIO (d) HClO4

Classify each as a strong or weak acid or base: (a) CH3NH2 (b) K2O (c) HI (d) HCOOH

Classify each as a strong or weak acid or base: (a) RbOH (b) HBr (c) H2Te (d) HClO

Classify each as a strong or weak acid or base: (a) HOCH2CH2NH2 (b) H2SeO4 (c) HS? (d) B(OH)3

What is an autoionization reaction? Write equations for the autoionization reactions of H2O and of H2SO4.

What is the difference between Kc and Kw for the autoionization of water?

(a) What is the change in pH when [OH] increases by a factor of 10? (b) What is the change in [H3O] when the pH decreases by 3 units?

Which solution has the higher pH? Explain. (a) A 0.1 M solution of an acid with Ka ? 1?104 or one with Ka ? 4?105 (b) A 0.1 M solution of an acid with pKa ? 3.0 or one with pKa ? 3.5 (c) A 0.1 M solution or a 0.01 M solution of a weak acid (d) A 0.1 M solution of a weak acid or a 0.1 M solution of a strong acid (e) A 0.1 M solution of an acid or a 0.01 M solution of a base (f) A solution of pOH 6.0 or one of pOH 8.0

(a) What is the pH of 0.0111 M NaOH? Is the solution neutral, acidic, or basic? (b) What is the pOH of 1.35?103 M HCl? Is the solution neutral, acidic, or basic?

(a) What is the pH of 0.0333 M HNO3? Is the solution neutral, acidic, or basic? (b) What is the pOH of 0.0347 M KOH? Is the solution neutral, acidic, or basic?

(a) What is the pH of 6.14?103 M HI? Is the solution neutral, acidic, or basic? (b) What is the pOH of 2.55 M Ba(OH)2? Is the solution neutral, acidic, or basic?

(a) What is the pH of 7.52?104 M CsOH? Is the solution neutral, acidic, or basic? (b) What is the pOH of 1.59? 03 M HClO4? Is the solution neutral, acidic, or basic?

(a) What are [H3O], [OH], and pOH in a solution with a pH of 9.85? (b) What are [H3O], [OH], and pH in a solution with a pOH of 9.43? 18

(a) What are [H3O], [OH], and pOH in a solution with a pH of 3.47? (b) What are [H3O], [OH], and pH in a solution with a pOH of 4.33? 18

(a) What are [H3O], [OH], and pOH in a solution with a pH of 4.77? (b) What are [H3O], [OH], and pH in a solution with a pOH of 5.65? 18

(a) What are [H3O], [OH], and pOH in a solution with a pH of 8.97? (b) What are [H3O], [OH], and pH in a solution with a pOH of 11.27? 18

How many moles of H3O or OH must you add per liter of HA solution to adjust its pH from 3.15 to 3.65? Assume a negligible volume change.

How many moles of H3O or OH must you add per liter of HA solution to adjust its pH from 9.33 to 9.07? Assume a negligible volume change.

How many moles of H3O or OH must you add to 5.6 L of HA solution to adjust its pH from 4.52 to 5.25? Assume a negligible volume change.

How many moles of H3O or OH must you add to 87.5 mL of HA solution to adjust its pH from 8.92 to 6.33? Assume a negligible volume change.

The two molecular scenes below depict the relative concentrations of H3O (purple) in solutions of the same volume (with counter ions and solvent molecules omitted for clarity). If the pH in scene A is 4.8, what is the pH in scene B?

Like any equilibrium constant, Kw changes with temperature. (a) Given that autoionization is endothermic, how does Kw change with rising T? Explain with a reaction that includes heat as reactant or product. (b) In many medical applications, the value of Kw at 37?C (body temperature) may be more appropriate than the value at 25?C, 1.0?1014. The pH of pure water at 37?C is 6.80. Calculate Kw, pOH, and [OH] at this temperature.

How are the Arrhenius and Brnsted-Lowry acid-base defi- nitions different? How are they similar? Name two BrnstedLowry bases that are not Arrhenius bases. Can you do the same for acids? Explain.

What is a conjugate acid-base pair? What is the relationship between the two members of the pair?

(a) A Brnsted-Lowry acid-base reaction proceeds in the net direction in which a stronger acid and stronger base form a weaker acid and weaker base. Explain. (b) The molecular scene at right depicts an aqueous solution of two conjugate acid-base pairs: HA/A and HB/B. The base in the first pair is represented by red spheres and the base in the second pair by green spheres; solvent molecules are omitted for clarity. Which is the stronger acid? Stronger base? Explain.

What is an amphiprotic species? Name one and write balanced equations that show why it is amphiprotic.

Write balanced equations and Ka expressions for these Brnsted-Lowry acids in water: (a) H3PO4 (b) C6H5COOH (c) HSO4

Write balanced equations and Ka expressions for these Brnsted-Lowry acids in water: (a) HCOOH (b) HClO3 (c) H2AsO4

Give the formula of the conjugate base: (a) HCl (b) H2CO3 (c) H2O

Give the formula of the conjugate base: (a) HPO4 2 (b) NH4 (c) HS 1

Give the formula of the conjugate acid: (a) NH3 (b) NH2 (c) nicotine, C10H14N2

Give the formula of the conjugate acid: (a) O2 (b) SO4 2 (c) H2O

n each equation, label the acids, bases, and conjugate pairs

In each equation, label the acids, bases, and conjugate pairs:

In each equation, label the acids, bases, and conjugate pairs:

In each equation, label the acids, bases, and conjugate pairs:

Write balanced net ionic equations for the following reactions, and label the conjugate acid-base pairs:

Write balanced net ionic equations for the following reactions, and label the conjugate acid-base pairs:

The following aqueous species constitute two conjugate acid-base pairs. Use them to write one acid- base reaction with Kc 1 and another with Kc ? 1: HS, Cl, HCl, H2S.

The following aqueous species constitute two conjugate acid-base pairs. Use them to write one acid- base reaction with Kc 1 and another with Kc ? 1: NO3 , F, HF, HNO3.

Use Figure 18.9 (p. 797) to determine whether Kc 1 for

Use Figure 18.9 (p. 797) to determine whether Kc 1 for

Use Figure 18.9 (p. 797) to determine whether Kc ? 1 for

Use Figure 18.9 (p. 797) to determine whether Kc ? 1 for

In each of the following cases, is the concentration of acid before and after dissociation nearly the same or very different? Explain your reasoning: (a) a concentrated solution of a strong acid; (b) a concentrated solution of a weak acid; (c) a dilute solution of a weak acid; (d) a dilute solution of a strong acid

A sample of 0.0001 M HCl has [H3O] close to that of a sample of 0.1 M CH3COOH. Are acetic acid and hydrochloric acid equally strong in these samples? Explain.

In which of the following solutions will [H3O] be approximately equal to [CH3COO]: (a) 0.1 M CH3COOH; (b) 1?107 M CH3COOH; (c) a solution containing both 0.1 M CH3COOH and 0.1 M CH3COONa? Explain.

Why do successive Kas decrease for all polyprotic acids?

A 0.15 M solution of butanoic acid, CH3CH2CH2COOH, contains 1.51?103 M H3O. What is the Ka of butanoic acid?

A 0.035 M solution of a weak acid (HA) has a pH of 4.88. What is the Ka of the acid?

Nitrous acid, HNO2, has a Ka of 7.1?104 . What are [H3O], [NO2 ], and [OH] in 0.60 M HNO2? 18

Hydrofluoric acid, HF, has a Ka of 6.8?104 . What are [H3O], [F], and [OH] in 0.75 M HF? 18

Chloroacetic acid, ClCH2COOH, has a pKa of 2.87. What are [H3O], pH, [ClCH2COO], and [ClCH2COOH] in 1.25 M ClCH2COOH?

Hypochlorous acid, HClO, has a pKa of 7.54. What are [H3O], pH, [ClO], and [HClO] in 0.115 M HClO?

In a 0.20 M solution, a weak acid is 3.0% dissociated. (a) Calculate the [H3O], pH, [OH], and pOH of the solution. (b) Calculate Ka of the acid.

In a 0.735 M solution, a weak acid is 12.5% dissociated. (a) Calculate the [H3O], pH, [OH], and pOH of the solution. (b) Calculate Ka of the acid.

A 0.250-mol sample of HX is dissolved in enough H2O to form 655 mL of solution. If the pH of the solution is 3.54, what is the Ka of HX?

A 4.85?103 -mol sample of HY is dissolved in enough H2O to form 0.095 L of solution. If the pH of the solution is 2.68, what is the Ka of HY?

The weak acid HZ has a Ka of 2.55?104 . (a) Calculate the pH of 0.075 M HZ. (b) Calculate the pOH of 0.045 M HZ.

The weak acid HQ has a pKa of 4.89. (a) Calculate the [H3O] of 3.5?102 M HQ. (b) Calculate the [OH] of 0.65 M HQ. 1

(a) Calculate the pH of 0.175 M HY, if Ka ? 1.50?104 . (b) Calculate the pOH of 0.175 M HX, if Ka ? 2.001? 02 .

6 (a) Calculate the pH of 0.55 M HCN, if Ka ? 6.2?1010. (b) Calculate the pOH of 0.044 M HIO3, if Ka ? 0.16.

Use Appendix C to calculate the percent dissociation of 0.55 M benzoic acid, C6H5COOH.

Use Appendix C to calculate the percent dissociation of 0.050 M CH3COOH

Use Appendix C to calculate [H2S], [HS], [S2], [H3O], pH, [OH], and pOH in a 0.10 M solution of the diprotic acid hydrosulfuric acid. 1

Use Appendix C to calculate [H2C2O4], [HC2O4 ], [C2O4 2], [H3O], pH, [OH], and pOH in a 0.200 M solution of the diprotic acid oxalic acid. Pr

Acetylsalicylic acid (aspirin), HC9H7O4, is the most widely used pain reliever and fever reducer. Find the pH of 0.018 M aqueous aspirin at body temperature (Ka at 37?C ? 3.6?104 ).

Formic acid, HCOOH, the simplest carboxylic acid, is used in the textile and rubber industries and is secreted as a defense by many species of ants (family Formicidae). Calculate the percent dissociation of 0.75 M HCOOH.

What is the key structural feature of all Brnsted-Lowry bases? How does this feature function in an acid-base reaction?

Why are most anions basic in H2O? Give formulas of four anions that are not basic

Except for the Na spectator ion, aqueous solutions of CH3COOH and CH3COONa contain the same species. (a) What are the species (other than H2O)? (b) Why is 0.1 M CH3COOH acidic and 0.1 M CH3COONa basic?

Write balanced equations and Kb expressions for these Brnsted-Lowry bases in water: (a) Pyridine, C5H5N (b) CO3 2

Write balanced equations and Kb expressions for these Brnsted-Lowry bases in water: (a) Benzoate ion, C6H5COO (b) (CH3)3N

Write balanced equations and Kb expressions for these Brnsted-Lowry bases in water: (a) Hydroxylamine, HONH2 (b) HPO4 2

Write balanced equations and Kb expressions for these Brnsted-Lowry bases in water: (a) Guanidine, (H2N)2CNH (double-bonded N is most basic) (b) Acetylide ion, HCPC

What is the pH of 0.070 M dimethylamine?

What is the pH of 0.12 M diethylamine?

What is the pH of 0.25 M ethanolamine?

What is the pH of 0.26 M aniline?

(a) What is the Kb of the acetate ion? (b) What is the Ka of the anilinium ion, C6H5NH3 ?

(a) What is the Kb of the benzoate ion, C6H5COO? (b) What is the Ka of the 2- hydroxyethylammonium ion, HOCH2CH2NH3 (pKb of HOCH2CH2NH2 ? 4.49)?

(a) What is the pKb of ClO2 ? (b) What is the pKa of the dimethylammonium ion, (CH3)2NH2 ?

(a) What is the pKb of NO2 ? (b) What is the pKa of the hydrazinium ion, H2NNH3 (Kb of hydrazine ? 8.5?107 )? 1

a) What is the pH of 0.150 M KCN? (b) What is the pH of 0.40 M triethylammonium chloride, (CH3CH2)3NHCl?

(a) What is the pH of 0.100 M sodium phenolate, C6H5ONa, the sodium salt of phenol? (b) What is the pH of 0.15 M methylammonium bromide, CH3NH3Br (Kb of CH3NH2 ? 4.4?104 )?

a) What is the pH of 0.65 M potassium formate, HCOOK? (b) What is the pH of 0.85 M NH4Br?

(a) What is the pH of 0.75 M NaF? (b) What is the pH of 0.88 M pyridinium chloride, C5H5NHCl?

Sodium hypochlorite solution, sold as chlorine bleach, is potentially dangerous because of the basicity of ClO, the active bleaching ingredient. What is [OH] in an aqueous solution that is 6.5% NaClO by mass? What is the pH of the solution? (Assume d of solution ? 1.0 g/mL.)

Codeine (C18H21NO3) is a narcotic pain reliever that forms a salt with HCl. What is the pH of 0.050 M codeine hydrochloride (pKb of codeine ? 5.80)?

Across a period, how does the electronegativity of a nonmetal affect the acidity of its binary hydride?

How does the atomic size of a nonmetal affect the acidity of its binary hydride?

A strong acid has a weak bond to its acidic proton, whereas a weak acid has a strong bond to its acidic proton. Explain.

Perchloric acid, HClO4, is the strongest of the halogen oxoacids, and hypoiodous acid, HIO, is the weakest. What two factors govern this difference in acid strength?

Choose the stronger acid in each of the following pairs: (a) H2SeO3 or H2SeO4 (b) H3PO4 or H3AsO4 (c) H2S or H2Te

Choose the weaker acid in each of the following pairs: (a) HBr or H2Se (b) HClO4 or H2SO4 (c) H2SO3 or H2SO

Choose the stronger acid in each of the following pairs: (a) H2Se or H3As (b) B(OH)3 or Al(OH)3 (c) HBrO2 or HBrO

Choose the weaker acid in each of the following pairs:(a) HI or HBr (b) H3AsO4 or H2SeO4 (c) HNO3 or HNO2

Use Appendix C to choose the solution with the lower pH: (a) 0.5 M CuSO4 or 0.25 M Al2(SO4)3 (b) 0.3 M ZnCl2 or 0.3 M PbCl2

Use Appendix C to choose the solution with the lower pH: (a) 0.1 M FeCl3 or 0.1 M AlCl3 (b) 0.1 M BeCl2 or 0.1 M CaCl2

Use Appendix C to choose the solution with the higher pH: (a) 0.2 M Ni(NO3)2 or 0.2 M Co(NO3)2 (b) 0.35 M Al(NO3)3 or 0.35 M Cr(NO3)3

Use Appendix C to choose the solution with the higher pH: (a) 0.1 M NiCl2 or 0.1 M NaCl (b) 0.1 M Sn(NO3)2 or 0.1 M Co(NO3)2

What determines whether an aqueous solution of a salt will be acidic, basic, or neutral? Give an example of each type of salt.

Why is aqueous NaF basic but aqueous NaCl neutral?

The NH4 ion forms acidic solutions, and the CH3COO ion forms basic solutions. However, a solution of ammonium acetate is almost neutral. Do all of the ammonium salts of weak acids form neutral solutions? Explain your answer.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) KBr; (b)NH4I; (c) KCN.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) Cr(NO3)3; (b) NaHS; (c) Zn(CH3COO)2.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) Na2CO3; (b) CaCl2; (c) Cu(NO3)2.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) CH3NH3Cl; (b) KClO4; (c) CoF2

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) SrBr2; (b) Ba(CH3COO)2; (c) (CH3)2NH2Br.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) Fe(HCOO)3; (b) KHCO3; (c) K2S.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) (NH4)3PO4; (b) Na2SO4; (c) LiClO.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral: (a) Pb(CH3COO)2; (b) Cr(NO2)3; (c) CsI

Rank the following salts in order of increasing pH of their 0.1 M aqueous solutions: (a) KNO3, K2SO3, K2S, Fe(NO3)2 (b) NH4NO3, NaHSO4, NaHCO3, Na2CO3

Rank the following salts in order of decreasing pH of their 0.1 M aqueous solutions: (a) FeCl2, FeCl3, MgCl2, KClO2 (b) NH4Br, NaBrO2, NaBr, NaClO2

The methoxide ion, CH3O, and amide ion, NH2 , are very strong bases that are leveled by water. What does this mean? Write the reactions that occur in the leveling process. What species do the two leveled solutions have in common?

Explain the differing extents of dissociation of H2SO4 in CH3COOH, H2O, and NH3.

In H2O, HF is weak and the other hydrohalic acids are equally strong. In NH3, however, all the hydrohalic acids are equally strong. Explain.

What feature must a molecule or ion have for it to act as a Lewis base? A Lewis acid? Explain the roles of these features.

How do Lewis acids differ from Brnsted-Lowry acids? How are they similar? Do Lewis bases differ from BrnstedLowry bases? Explain

(a) Is a weak Brnsted-Lowry base necessarily a weak Lewis base? Explain with an example. (b) Identify the Lewis bases in the following reaction: (c) Given that Kc 1 for the reaction in part (b), which Lewis base is stronger?

In which of the three acid-base concepts can water be a product of an acid-base reaction? In which is it the only product?

(a) Give an example of a substance that is a base in two of the three acid-base definitions, but not in the third. (b) Give an example of a substance that is an acid in one of the three acid-base definitions, but not in the other two.

Which are Lewis acids and which are Lewis bases? (a) Cu2 (b) Cl (c) SnCl2 (d) OF2

Which are Lewis acids and which are Lewis bases? (a) Na (b) NH3 (c) CN (d) BF3

Which are Lewis acids and which are Lewis bases? (a) BF3 (b) S2 (c) SO3 2 (d) SO3

Which are Lewis acids and which are Lewis bases? (a) Mg2 (b) OH (c) SiF4 (d) BeCl2

Identify the Lewis acid and Lewis base in each equation:

Identify the Lewis acid and Lewis base in each equation:

Classify the following as Arrhenius, Brnsted-Lowry, or Lewis acid-base reactions. A reaction may fit all, two, one, or none of the categories

Classify the following as Arrhenius, Brnsted-Lowry, or Lewis acid-base reactions. A reaction may fit all, two, one, or none of the categories

Pantothenic acid (C9H17NO5; vitamin B3) is shown below. This biologically active molecule is an optical isomer that behaves like a monoprotic Brnsted-Lowry acid in water. CN H2O BA HCN OH N2 3H2BA 2NH3 Al(OH)3 3HNO3BA Al3 3H2O 3NO3 Cu2 4Cl BA CuCl4 2 AlCl3 Cl BA AlCl4 2HCl BA H2 Cl2 H2SO4 NH3BA HSO4 NH4 Ag 2NH3BA Ag(NH3)2 4CO Ni BA Ni(CO)4 H2O HBA OH H2 Fe3 2H2O BA FeOH2 H3O F BF3BA BF4 CO2 H2O BA H2CO3 Na 6H2O BA Na(H2O)6 N H O C (a) Use the molecular formula to write the equation for the reaction of pantothenic acid with water and the Ka expression. (b) Which C atom is the chiral center? 18.146 Chloral (Cl3CCH O) forms a monoh

Chloral (Cl3CCH O) forms a monohydrate, chloral hydrate, the sleep-inducing depressant called knockout drops in old movies. (a) Write two possible structures for chloral hydrate, one involving hydrogen bonding and one that is a Lewis adduct. (b) What spectroscopic method could be used to identify the real structure? Explain

In humans, blood pH is maintained within a narrow range: acidosis occurs if the blood pH is below 7.35, and alkalosis occurs if the pH is above 7.45. Given that the pKw of blood is 13.63 at 37C (body temperature), what is the normal range of [H3O] and of [OH] ? in blood?

The disinfectant phenol, C6H5OH, has a pKa of 10.0 in water, but 14.4 in methanol. (a) Why are the values different? (b) Is methanol is a stronger or weaker base than water? (c) Write the dissociation reaction of phenol in methanol. (d) Write an expression for the autoionization constant of methanol.

When carbon dioxide dissolves in water, it undergoes a multistep equilibrium process, with Koverall ? 4.5?10?7 , which is simplified to the following: (a) Classify each step as a Lewis or a Brnsted-Lowry reaction. (b) What is the pH of nonpolluted rainwater in equilibrium with clean air ( in clean air ? 3.2?10?4 atm; Henrys law constant for CO2 at 25C is 0.033 mol/L atm)? (c) What is [CO3 2?] in rainwater (Ka of HCO3 ? ? 4.7?10?11)? (d) If the partial pressure of CO2 in clean air doubles in the next few decades, what will the pH of rainwater become?

Seashells are mostly calcium carbonate, which reacts with H3O according to the equation If Kw increases at higher pressure, will seashells dissolve more rapidly near the surface of the ocean or at great depths? Explain.

Many molecules with central atoms from Period 3 or higher take part in Lewis acid-base reactions in which the central atom expands its valence shell. SnCl4 reacts with (CH3)3N as follows: CaCO3(s)H3O (aq) BA Ca2 (aq)HCO3 ?(aq)H2O(l) PCO2 H2CO3(aq) H2O(l) BA HCO3 ?(aq) H3O(aq) CO2(g) H2O(l) BA H2CO3(aq) 828 Chapter 18 Acid-Base Equilibria beaker A is at equilibrium. Calculate Q for B, C, and D to determine which, if any, is also at equilibrium. (b) For any not at equilibrium, in which direction does the reaction proceed? (c) Does dilution affect the extent of dissociation of a weak acid? Explain. + Sn Cl N C H (a) Identify the Lewis acid and the Lewis base in the reaction. (b) Give the nl designation of the sublevel of the central atom in the acid before it accepts the lone pair. 18.152

A chemist makes four successive 1:10 dilutions of 1.0?10?5 M HCl. Calculate the pH of the original solution and of each diluted solution (through 1.0?10?9 M HCl).

Chlorobenzene, C6H5Cl, is a key intermediate in the manufacture of dyes and pesticides. It is made by the chlorination of benzene, catalyzed by FeCl3, in this series of steps: (1) (2) (3) (4) (a) Which of the step(s) is (are) Lewis acid-base reactions? (b) Identify the Lewis acids and bases in each of those steps

The beakers shown contain 0.300 L of aqueous solutions of a moderately weak acid HY. Each particle represents 0.010 mol; solvent molecules are omitted for clarity. (a) The reaction in beaker A is at equilibrium. Calculate Q for B, C, and D to determine which, if any, is also at equilibrium. (b) For any not at equilibrium, in which direction does the reaction proceed? (c) Does dilution affect the extent of dissociation of a weak acid? Explain.

Hydrogen peroxide, H2O2 (pKa ? 11.75), is a bleaching agent and antiseptic. It is sold as 3% H2O2 by mass and contains 0.001% H3PO4 by mass to stabilize the solution. Which contributes more H3O to the solution, the H2O2 or the H3PO4?

The strength of an acid or base is related to its strength as an electrolyte. (a) Is the electrical conductivity of 0.1 M HCl higher, lower, or the same as that of 0.1 M CH3COOH? Explain. (b) Is the electrical conductivity of 1?10?7 M HCl higher, lower, or the same as that of 1?10?7 M CH3COOH? Explain

Esters, RCOOR?, are formed by the reaction of carboxylic acids, RCOOH, and alcohols, R?OH, where R and R? are hydrocarbon groups. Many esters are responsible for the odors of fruit and, thus, have important uses in the food and cosmetics industries. The first two steps in the mechanism of ester formation are (1) (2) Identify the Lewis acids and Lewis bases in these two steps.

Three beakers contain 100. mL of 0.10 M acid, either HCl, HClO2, or HClO. (a) Find the pH of each. (b) Describe quantitatively how to make the pH equal in the beakers through the addition of water only.

Human urine has a normal pH of 6.2. If a person eliminates an average of 1250. mL of urine per day, how many H ions are eliminated per week?

Liquid ammonia autoionizes like water: where (am) represents solvation by NH3. (a) Write the ion- product constant expression, Kam. (b) What are the strongest acid and base that can exist in NH3(l)? (c) HNO3 and HCOOH are leveled in NH3(l). Explain with equations. (d) At the boiling point (?33C), Kam ? 5.1?10?27. Calculate [NH4 ] at this temperature. (e) Pure sulfuric acid also autoionizes. Write the ion-product constant expression, Ksulf, and find the concentration of the conjugate base at 20C (Ksulf ? 2.? 0?4 at 20C). 18

Autoionization (see Problem 18.160) occurs in methanol (CH3OH) and in ethylenediamine (NH2CH2CH2NH2). (a) The autoionization constant of methanol (Kmet) is 2?10?17. What is [CH3O?] in pure CH3OH?(b) The concentration of NH2CH2CH2NH in pure NH2CH2CH2NH2 is 2?108 M. What is the autoionization constant of ethylenediamine (Ken)?

Thiamine hydrochloride (C12H18ON4SCl2) is a watersoluble form of thiamine (vitamin B1; Ka ? 3.37?107 ). How many grams of the hydrochloride must be dissolved in 10.00 mL of water to give a pH of 3.50?

Tris(hydroxymethyl)aminomethane, known as TRIS or THAM, is a water-soluble base used to synthesize surfactants and pharmaceuticals, as an emulsifying agent in cosmetics, and in cleaning mixtures for textiles and leather. In biomedical research, solutions of TRIS are used to maintain nearly constant pH for the study of enzymes and other cellular components. Given that the pKb is 5.91, calculate the pH of 0.075 M TRIS

When Fe3 salts are dissolved in water, the solution becomes acidic due to formation of Fe(H2O)5OH2 and H3O. The overall process involves both Lewis and Brnsted-Lowry acid-base reactions. Write the equations for the process.

What is the pH of a vinegar with 5.0% (w/v) acetic acid in water?

How would you differentiate between a strong and a weak monoprotic acid from the results of the following procedures? (a) Electrical conductivity of an equimolar solution of each acid is measured. (b) Equal molarities of each are tested with pH paper. (c) Zinc metal is added to solutions of equal concentration.

At 50?C and 1 atm, Kw ? 5.19?1014. At these conditions, find (a) [H3O] in pure water, (b) [H3O] in 0.010 M NaOH, and (c) [OH] in 0.0010 M HClO4. (d) Find [H3O] in 0.0100 M KOH at 100?C and 1000 atm (Kw ? 1.10?1012). (e) Find the pH of pure water at 10? and 1000 atm. 1

The catalytic efficiency of an enzyme is called its activity and refers to the rate at which it catalyzes the reaction. Most enzymes have optimum activity over a relatively narrow pH range, which is related to the pH of the local cellular fluid. The pH pro- files of three digestive enzymes are shown. Problems 829 PH3BCl3(s) is introduced into a 3.0-L container at a certain temperature, 8.4?103 mol of PH3 is present at equilibrium: (a) Find Kc for the reaction at this temperature. (b) Draw a Lewis structure for the reactant. 18.172 A 1.000 m solution of chloroacetic acid (ClCH2COOH) freezes at 1.93?C. Find the Ka of chloroacetic acid. (Assume the molarities equal the molalities.) 18.173 Sodium stearate (C17H35COONa) is a major component of bar soap. The Ka of the stearic acid is 1.3?105 . What is the pH of 10.0 mL of a solution containing 0.42 g of sodium stearate? 18.174 Calcium propionate [Ca(CH3CH2COO)2; calcium propanoate] is a mold inhibitor used in food, tobacco, and pharmaceuticals. (a) Use balanced equations to show whether aqueous calcium propionate is acidic, basic, or neutral. (b) Use Appendix C to find the resulting pH when 8.75 g of Ca(CH3CH2COO)2 dissolves in enough water to give 0.500 L of solution. 18.175 A site in Pennsylvania receives a total annual deposition of 2.688 g/m2 of sulfate from fertilizer and acid rain. The ratio by mass of ammonium sulfate/ammonium bisulfate/sulfuric acid is 3.0/5.5/1.0. (a) How much acid, expressed as kg of sulfuric acid, is deposited over an area of 10. km2 ? (b) How many pounds of CaCO3 are needed to neutralize this acid? (c) If 10. km2 is the area of an unpolluted lake 3 m deep and there is no loss of acid, what pH would be attained in the year? (Assume constant volume.) 18.176 (a) If Kw ? 1.139?1015 at 0?C and 5.474?1014 at 50?C, find [H3O] and pH of water at 0?C and 50?C. (b) The autoionization constant for heavy water (deuterium oxide, D2O) is 3.64?1016 at 0?C and 7.89?1015 at 50?C. Find [D3O] and pD of heavy water at 0?C and 50?C. (c) Suggest a reason for these differences. 18.177 HX ( ? 150. g/mol) and HY ( ? 50.0 g/mol) are weak acids. A solution of 12.0 g/L of HX has the same pH as one containing 6.00 g/L of HY. Which is the stronger acid? Why? 18.178 The beakers below depict the aqueous dissociations of weak acids HA (blue and green) and HB (blue and yellow); solvent molecules are omitted for clarity. If the HA solution is 0.50 L, and the HB solution is 0.25 L, and each particle represents 0.010 mol, find the Ka of each acid. Which acid, if either, is stronger? PH3BCl3(s) BA PH3(g) BCl3(g). Enzyme activity pH Pepsin Salivary amylase Trypsin 2 4 6 8 10 Salivary amylase begins digestion of starches in the mouth and has optimum activity at a pH of 6.8; pepsin begins protein digestion in the stomach and has optimum activity at a pH of 2.0; and trypsin, released in pancreatic juices, continues protein digestion in the small intestine and has optimum activity at a pH of 9.5. Calculate [H3O] in the local cellular fluid for each enzyme. 18.169 Acet

Acetic acid has a Ka of 1.8?105 , and ammonia has a Kb of 1.8?105 . Find [H3O], [OH], pH, and pOH for (a) 0.240 M acetic acid and (b) 0.240 M ammonia. 1

The uses of sodium phosphate include clarifying crude sugar, manufacturing paper, removing boiler scale, and washing concrete. What is the pH of a solution containing 33 g of Na3PO4 per liter? What is [OH] of this solution?

The Group 5A(15) hydrides react with boron trihalides in a reversible Lewis acid-base reaction. When 0.15 mol of PH3BCl3(s) is introduced into a 3.0-L container at a certain temperature, 8.4?103 mol of PH3 is present at equilibrium: (a) Find Kc for the reaction

A 1.000 m solution of chloroacetic acid (ClCH2COOH) freezes at 1.93?C. Find the Ka of chloroacetic acid. (Assume the molarities equal the molalities.)

Sodium stearate (C17H35COONa) is a major component of bar soap. The Ka of the stearic acid is 1.3?105 . What is the pH of 10.0 mL of a solution containing 0.42 g of sodium stearate?

Calcium propionate [Ca(CH3CH2COO)2; calcium propanoate] is a mold inhibitor used in food, tobacco, and pharmaceuticals. (a) Use balanced equations to show whether aqueous calcium propionate is acidic, basic, or neutral. (b) Use Appendix C to find the resulting pH when 8.75 g of Ca(CH3CH2COO)2 dissolves in enough water to give 0.500 L of solution

A site in Pennsylvania receives a total annual deposition of 2.688 g/m2 of sulfate from fertilizer and acid rain. The ratio by mass of ammonium sulfate/ammonium bisulfate/sulfuric acid is 3.0/5.5/1.0. (a) How much acid, expressed as kg of sulfuric acid, is deposited over an area of 10. km2 ? (b) How many pounds of CaCO3 are needed to neutralize this acid? (c) If 10. km2 is the area of an unpolluted lake 3 m deep and there is no loss of acid, what pH would be attained in the year? (Assume constant volume.)

(a) If Kw ? 1.139?1015 at 0?C and 5.474?1014 at 50?C, find [H3O] and pH of water at 0?C and 50?C. (b) The autoionization constant for heavy water (deuterium oxide, D2O) is 3.64?1016 at 0?C and 7.89?1015 at 50?C. Find [D3O] and pD of heavy water at 0?C and 50?C. (c) Suggest a reason for these differences. 18.1

HX ( ? 150. g/mol) and HY ( ? 50.0 g/mol) are weak acids. A solution of 12.0 g/L of HX has the same pH as one containing 6.00 g/L of HY. Which is the stronger acid? Why?

The beakers below depict the aqueous dissociations of weak acids HA (blue and green) and HB (blue and yellow); solvent molecules are omitted for clarity. If the HA solution is 0.50 L, and the HB solution is 0.25 L, and each particle represents 0.010 mol, find the Ka of each acid. Which acid, if either, is stronger?

In his acid-base studies, Arrhenius discovered an important fact involving reactions like the following: (a) Complete the reactions and use the data for the individual ions in Appendix B to calculate each H?rxn. (b) Explain your results and use them to predict H?rxn for

Putrescine [NH2(CH2)4NH2], found in rotting animal tissue, is now known to be in all cells and essential for normal and abnormal (cancerous) growth. It also plays a key role in the formation of GABA, a neurotransmitter. A 0.10 M aqueous solution of putrescine has [OH] ? 2.1?103 . What is the Kb?

The molecular scene depicts the relative concentrations of H3O (purple) and OH (green) in an aqueous solution at 25?C. (Counter ions and solvent molecules are omitted for clarity.) (a) Calculate the pH. (b) How many H3O ions would you have to draw for every OH ion to depict a solution of pH 4? 18

Polymers are not very soluble in water, but their solubility increases if they have charged groups. (a) Casein, a milk protein, contains many COO groups on its side chains. How does the solubility of casein vary with pH? (b) Histones are proteins essential to the function of DNA. They are weakly basic due to the presence of side chains with NH2 and NNH groups. How does the solubility of a histone vary with pH?

Hemoglobin (Hb) transports oxygen in the blood: In blood, [H3O] is held nearly constant at 4?108 M. (a) How does the equilibrium position change in the lungs? (b) How does it change in O2-deficient cells? (c) Excessive vomiting may lead to metabolic alkalosis, in which [H3O] in blood decreases. How does this condition affect the ability of Hb to transport O2? (d) Diabetes mellitus may lead to metabolic acidosis, in which [H3O] in blood increases. How does this condition affect the ability of Hb to transport O2? 18

Nitrogen is discharged from wastewater treatment facilities into rivers and streams, usually as NH3 and NH4 : One strategy for removing it is to raise the pH and strip the NH3 from solution by bubbling air through the water. (a) At pH 7.00, what fraction of the total nitrogen in solution is NH3, defined as [NH3]/([NH3] [NH4 ])? (b) What is the fraction at pH 10.00? (c) Explain the basis of ammonia stripping. 1

Kevlar, a polymeric aromatic amide, is synthesized from the monomers p-phenylenediamine (left) and terephthaloyl chloride (right). The polymer strands are initially aligned randomly, but they are dissolved and spun to give a lightweight, flexible product that is five times stronger than steel of the same weight. (a) Describe this step in terms of a Lewis acid-base reaction. (b) Would you expect water or ammonia to react faster with an acid chloride? Explain

A solution of propanoic acid (CH3CH2COOH), made by dissolving 7.500 g in sufficient water to make 100.0 mL, has a freezing point of 1.890?C. (a) Calculate the molarity of the solution. (b) Calculate the molarity of the propanoate ion. (Assume the molarity of the solution equals the molality.) (c) Calculate the percent dissociation of propanoic acid.

The antimalarial properties of quinine (C20H24N2O2) saved thousands of lives during construction of the Panama Canal. This substance is a classic example of the medicinal wealth of tropical forests. Both N atoms are basic, but the N (colored) of the 3? amine group is far more basic (pKb ? 5.1) than the N within the aromatic ring system (pKb ? 9.7). (a) A saturated solution of quinine in water is only 1.6?103 M. What is the pH of this solution? (b) Show that the aromatic N contributes negligibly to the pH of the solution. (c) Because of its low solubility, quinine is given as the salt quinine hydrochloride (C20H24N2O2HCl), which is 120 times more soluble than quinine. What is the pH of 0.33 M quinine hydrochloride? (d) An antimalarial concentration in water is 1.5% quinine hydrochloride by mass (d ? 1.0 g/mL). What is the pH?

Drinking water is often disinfected with Cl2, which hydrolyzes to form HClO, a weak acid but powerful disinfectant: The fraction of HClO in solution is defined as (a) What is the fraction of HClO at pH 7.00 (Ka of HClO ? 2.9?108 )? (b) What is the fraction at pH 10.00?

The following scenes represent three weak acids HA (where A ? X, Y, or Z) dissolved in water (H2O is not shown): [HClO] [HClO] [ClO] Cl2(aq) 2H2O(l) HClO(aq) H3O(aq) Cl(aq) The first step in the reaction of an amine with an acid chloride is HX HY HZ HA = H3O+ = A = (a) Rank the acids in order of increasing Ka. (b) Rank the acids in order of increasing pKa. (c) Rank the conjugate bases in order of increasing pKb. (d) What is the percent dissociation of HX? (e) If equimolar amounts of the sodium salts of the acids (NaX, NaY, and NaZ) were dissolved in water, which solution would have the highest pOH? The lowest pH? CH C