Question

1. A certain solution has a concentration of 1.0 x 10^-4 M of OH^-. Which of the following statements is true?

Select one:

A. The solution has a pH of 10.

B. The solution is acidic.

C. The solution has a pH of 4.

D. The solution has a H⁺ concentration of 1.0 x 10^-4 M as well.

2. How do you know an acid is weak?

Select one:

a. It does not totally dissociate in water, setting up a reversible reaction.

b. It totally dissociates into ions in water.

c. It will not enter the gas phase.

d. It turns blue when reacted with metals.

3. Which of the following is a weak acid?

Select one:

a. HCl

b. H₂SO₄

c. HF

d. HNO_3'

4. The designation pH means:

Select one:

a. negative log of H+ concentration

b. negative log of H- concentration

c. negative log of OH- concentration

d. negative log of OH+ concentration

Answer 1

(1) concentration of 1.0 x 10^-4 M of OH^-

This means concentration of [OH-] = 1.0 x 10^-4 M

then p[OH] = -log [OH-]

p[OH-] = -log[1.0 x 10^-4]

p[OH] = 4

Now, from relation: pH + p[OH] = 14

pH = 14 - p[OH]

pH = 14 - 4

pH = 10 and solution is basic (correct option a.)

(2) Correct option (a.) It does not totally dissociate in water, setting up a reversible reaction.

Weak acids can not 100% ionize.

(3) Among given acids, only HF is weak acid with pKa value 3.17

Correct option (c.) HF

(4) Correct option: (a.) negative log of H+ concentration

pH = -log[H+]