Honors Chemistry

Answers to Chapter 14 Study Questions

 

1. Fill in the following table:

[H+]

[OH]

pH

pOH

acid, base or neutral?

1.0 x 10-4 M

1.0 x 10-10 M

4.0

10.0

acid

1.0 x 10-7 M

1.0 x 10-7 M

7.0

7.0

neutral

1.0 x 10-12 M

1.0 x 10-2 M

12.0

2.0

base

1.0 M

1.0 x 10-14 M

0.0

14.0

acid

3.2 x 10-4 M

3.2 x 10-11 M

3.5

10.5

acid

4.6 x 10-3 M

2.2 x 10-12 M

2.3

11.7

acid

1.2 x 10-3 M

8.2 x 10-12 M

2.9

11.1

acid

 

2. a) strong, acid, HNO3(aq) H+(aq) + NO3-(aq)

b) weak, acid, HF (aq) H+(aq) + F-(aq)

c) weak, base, F-(aq) + H2O HF(aq) + OH-(aq)

d) amphoteric, acid: HSO3-(aq) H+(aq) + SO32-(aq);

base: HSO3-(aq) + H2O H2SO3 (aq) + OH-(aq)

e) strong, base, KOH(s) K+(aq) + OH-(aq)

 

3. a) HCl = strong acid; [H+] = = 1.0 x 10-3 M; pH = 3.0

b) NaOH = strong base; [NaOH] = = 0.010 mol/L =

[OH-] = [NaOH] = 1.0 x 10-2 M; [H+] = 1.0 x 10-12 M; pH = 12.0

 

c) HBr = strong acid; 5.0 mL = 5.0 x 10-3 L; V1 x M1 = V2 x M2

(5.0 x 10-3 L) x (0.40 M) = (20 L) x M2; M2 = (5.0 x 10-3 L) x (0.40 M)/(20 L)

M2 = 1.0 x 10-4 M = [H+]; pH = 4.0.

d) Ka = ; [H+] = [A-] = x; [HA] 0.10 M; 6.4 x 10-5 =

x2 = (6.4 x 10-5)(0.10) = 6.4 x 10-6 M; x = (6.4 x 10-6) = 2.5 x 10-3; pH = 2.6

e) Kb = ; [HClO] = [OH-] = x; [ClO-] 0.20 M;

Ka Kb = 10-14; Kb = = 2.9 10-7

Kb = ; 2.9 10-7 = ; x2 = (2.9 x 10-7)(0.20 M) = 5.8 x 10-8

x = [OH-] = (5.8 x 10-8) = 2.4 x 10-4 M; pOH = 3.6; pH = 14.0 - 3.6 = 10.4

f) 0.10 mol H+ and 0.10 mol OH- 0.10 mol H2O; 0.10 mol H+ remains in 1.0 L.

[H+] = (0.10 mol)/(1.0 L) = 1.0 x 10-1 M; pH = 1.0

4. a) H2CO3(aq) H+(aq) + HCO3-(aq)

b) Ka =

c) pH = 3.68; [H+] = [HCO3-] = 10-3.68 = 2.1 x 10-4 M; [H2CO3] 0.10 M

Ka = ; Ka = = 4.4 x 10-7

d) Ka Kb = 1.0 x 10-14; Kb = (1.0 x 10-14)/(4.4 x 10-7) = 2.3 x 10-8

 

5. a) It can be an H+ acceptor.

b) CH3COOH

c) CH3COO-(aq) + H2O CH3COOH(aq) + OH-(aq)

 

6. a) HNO2(aq) + OH-(aq) NO2-(aq) + H2O

acid1 base2 base1 acid2

 

7. weakest acid strongest acid: HCN < HC2H3O2 < HF < HCl

weakest base strongest base: Cl- < F- < C2H3O2- < CN-

 

8. a) basic

b) acidic (NH4+ is an acid, NO3- is neutral)

c) neutral

d) basic (Na+ is neutral; F- is a weak base)