1. Which of these statements about the common-ion effect is most correct? [A] Co

ID: 966905 • Letter: 1

Question

1. Which of these statements about the common-ion effect is most correct?

[A] Common ions alter the equilibrium constant for the reaction of an ionic solid with water.

[B] The solubility of a salt MA is decreased in a solution that already contains either M+ or A

[C] The solubility of a salt MA is affected equally by addition of either A or a non-common ion

[D] The common-ion effect does not apply to unusual ions like SO32

[E] The solubility of a salt remains unaffected on addition of a common ion

2. Consider the equilibrium

B(aq)+H2O(l) HB+(aq)+OH(aq).

Suppose that a salt of HB+ is added to a solution of B at equilibrium

[A] The concentration of B(aq) will increase

[B] The concentration of B(aq) will decrease

[C] The concentration of B(aq) will stay the same

[D] The concentration of OH- will increase

[E] The concentration of OH- will remain the same

3. What is the pH of a buffer prepared by adding 0.708 mol of the weak acid HA to 0.507 mol

NaA in 2.00 L of solution? The dissociation constant of HA is 5.66 x 10-7. Use upto three

decimal points.

[A] 5.412 [B] 6.102 [C] 6.271 [D] 5.512 [E] 6.515

1) [B] The solubility of a salt MA is decreased in a solution that already contains either M+ or A

2) [A] The concentration of B(aq) will increase

3) option [B] 6.102

pH = pKa + log [salt / acid]

= 6.25 + log [0.507 / 0.708]

= 6.102

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.