Free Printable 7.1 Acids and Bases

1.

HCO₃^- ion acts as Bronsted-Lowry acid in the reaction

a)

$HCO_3^-(aq)+H_3O^+(aq)\rightarrow2H_2O(l)+CO\ _2$

b)

$HCO_{3^-}(aq)+H_2O(l)→H_2CO_3(aq)+OH^-(aq)$

c)

$HCO_3^-(aq)+OH^-(aq)→H_2O(l)+CO_3^{2^-}\left(aq\right)$

d)

$HCO_3^-(aq)+HSO_4^-(aq)→H_2CO_3(aq)+SO_{4^2}-\left(aq)\right)$

2.

The pH value of a solution of NaOH 2.50x10^-3 M is

a)

2.60

b)

4.50

c)

11.40

d)

12.30

3.

Calculate the concentration of hydroxide ions in an aqueous solution containing 4.0x10^-8 M hydronium ions.

a)

4.0x10^-22

b)

2.5x10^-7

c)

1.0x10^-12

d)

4.0x10^-8

4.

A solution in which [H⁺] = 10^-8 M has a pH of ___ and is ___.

a)

8, acidic

b)

6, acidic

c)

8, basic

d)

6, basic

5.

What is the approximate pH of a solution labeled 6 x 10^-5 M HBr?

a)

4.2

b)

4.5

c)

5.8

d)

9.8

6.

The pH of a solution is 4.80. What is the concentration of hydroxide ions in this solution?

a)

4.2 x 10^-9 M

b)

1.6 x 10^-5 M

c)

3.6 x 10^-12 M

d)

6.3 x 10^-10 M

7.

What is the pH of 500 mL of solution containing 0.0124 grams of Ca(OH)₂ ? (RMM = 74)

a)

3.8

b)

10.2

c)

3.2

d)

10.8

8.

In a sample of pure water, only one of the following statements is always true at all conditions of temperature and pressure. Which one is always true?

a)

[H₃O⁺] = 1.0 x 10^-7 M

b)

pH = 7.0

c)

pOH = 7.0

d)

[H₃O⁺] = [OH^-]

9.

If K_w is 2.9 x 10^-15 at 10^oC, what is the pH of pure water at 10^oC?

a)

6.72

b)

7.00

c)

7.27

d)

7.53

10.

Which of the following is true about a 0.10 M solution of a weak acid, HX?

a)

[X^-] = 0.10 M

b)

[H⁺] = 0.10 M

c)

pH = 1

d)

[HX] > [H⁺]

11.

Which of the following solutions has the lowest pH at 25^oC? (No calculations required.)

a)

0.2 M benzoic acid, Ka = 6.3 x 10^-5

b)

0.2 M methanoic acid, Ka = 1.8 x 10^-4

c)

0.2 M carbonic acid, Ka = 4.4 x 10^-7

d)

0.2 M hypochlorous acid, Ka = 2.9 x 10^-8

12.

Which of the following solutions has the highest pH at 25^oC? (No calculations required.)

a)

Ammonium ion, Ka = 5.8 x 10^-10

b)

Hydrogen sulfate ion, Ka = 1.0 x 10^-2

c)

Hydrogen carbonate ion, Ka = 4.7 x 10^-11

d)

Hydrogen phosphate ion, Ka = 4.2 x 10^-13

13.

The pH of a 0.02 M solution of an unknown weak acid is 3.7. what is the pK_a of this acid?

a)

4.9

b)

5.7

c)

3.2

d)

2.8

14.

A 0.10 M solution of a weak acid, HX, is 0.059% ionized. Calculate K_a for the acid.

a)

3.8 x 10^-9

b)

4.2 x 10^-6

c)

3.5 x 10^-8

d)

6.5 x 10^-7

15.

What is the pH of an 1.2 M HF solution?

Ka = 6.6 x 10^-4moldm^-3

a)

3.10

b)

1.62

c)

1.55

d)

3.25

16.

1. Which reaction is NOT Lewis acid-base reaction?

a)

$C+O_2\rightarrow CO_2$

b)

$BeF_2+2F^-\rightarrow BeF_4^2-$

c)

$NH_3+BF_3\ \rightarrow H_3NBF_3$

d)

$(C_4H_9)_3N+SO_{3\ }\rightarrow\ (C_4H_9)_3NSO_3$

17.

A solution of weak acid, HA 0.2 M ionises 1.8%. Calculate the value of K_a for this acid.

a)

3.6x10^-5

b)

1.8x10^-5

c)

0.9x10^-5

d)

6.5x10^-5

18.

What is meant by salt hydrolysis?

a)

The producing of cation and anion from the reaction between strong base and strong acid.

b)

Salt hydrolysis occurs when any soluble salts dissolve in water

c)

The producing of cation and anion from the reaction between weak acid and weak base.

d)

Salt hydrolysis occurs when there is a reaction between cation, or anion or both and water.

19.

Choose the correct statement about ethanoic acid with a concentration of 2.0x10^-3 M.

a)

Its pH is 2.7

b)

H₃O⁺ concentration is 1.9x10^-4 M

c)

The acid ionised completely in the aqueous solution

d)

The K_a value increases with increasing concentration of the acid.

20.

pH = -log [ $H^+$ ]

a)

True

b)

False

7.1 Acids and Bases

Total questions: 20

Worksheet time: 5hrs 0mins

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