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Worksheets

Pka and Pkb

Total questions: 11

Worksheet time: 8mins

Name
Class
Date
1.

calculate the Ka of a solution with a pKb of 3.38

a)

3.38x10-11

b)

6.76x10-11

c)

2.40x10-11

d)

2.39x10-11

2.

calculate the pKb of solution with a pKa of 6.9

a)

7.1

b)

6.5

c)

14

d)

9.6

3.

Calculate the Kb of a solution that has a pKb of 4.2

a)

0.62

b)

6.3x10-5

c)

9.8

d)

4.2

4.

The magnitude of Kw indicates that ______________.

a)

water autoionizes very slowly

b)

water autoionizes very quickly

c)

water autoionizes only to a very small extent

d)

the autoionization of water is exothermic

5.

How would you calculate Kb for the formate ion (HCOO–), given that the Ka for formic acid (HCOOH) is 1.8 × 10–4? (Kw=1.0 × 10–14)

a)

Kb = Ka × Kw

b)

Kb = Kw / Ka

c)

Kb = Ka / Kw

d)

Kb = Kw + Ka

6.

In which of the following aqueous solutions does the weak acid exhibit the highest percentge of ionization?

a)

.01 M HC2H3O2 . (Ka 1.8 x 10 -5)

b)

.01 M HNO2 . ( Ka =4.5 x 10 -4)

c)

.01 M HClO . (Ka= 3.0 x 10 -8)

d)

.01 M HF (Ka= 6.8 x 10 -4)

7.

HA is a weak acid. Which equilibrium corresponds to the equilibrium constant Kb for A-?

a)

HA (aq) + H2O (l) <---> H2A+ (aq) + OH-(aq)

b)

A- (aq) + H3O+ (aq) <---> HA (aq) + H2O (l)

c)

HA (aq) + OH- (aq) <---> H2O (l) + H+ (aq)

d)

A- (aq) + H2O (l) <---> HA (aq) + OH- (aq)

e)

A- (aq) + OH- (aq) <---> HOA2- (aq)

8.

A- is a weak base. Which equilibrium corresponds to the equilibrium constant Ka for HA?

a)

HA (aq) + H2O (l) <---> H2A+ (aq) + OH- (aq)

b)

A- (aq) + H3O+ (aq) <---> HA (aq) + H2O (l)

c)

HA (aq) + H2O (l) <---> H3O+ (aq) + A- (aq)

d)

A- (aq) + H2O (l) <---> HA (aq) + OH- (aq)

e)

A- (aq) + OH- (aq) <---> HOA2- (aq)

9.

Using the data in the table, which of the conjugate bases below is the weakest base?

a)

OAc-

b)

C7H5O2-

c)

NO2-

d)

F-

e)

OAc- and C7H5O2-

10.

Using the data in the table, which of the conjugate acids below is the weakest acid?

a)

HClO

b)

HCO3-

c)

H2S

d)

NH3CH3+

e)

H2S and HClO

11.

Z- is a weak base. An aqueous solution of NaZ is prepared by dissolving 0.350 mol of NaZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 8.93 at 25.0 0C. What is the Kb of the solution?

a)

1.2 x 10-5

b)

6.9 x 10 -9

c)

2.1 x 10 -10

d)

2.8 x 10 -12