Question

For each of the salts #1 and #2, match the salts A,B,C,D that can be compared directly, using K_sp values, to estimate solubilities.

(If more than one salt can be directly compared, include all the relevant salts by writing your answer as a string of characters without punctuation, e.g, ABC.)

1. Barium Sulfite

2. Magnesium Hydroxide

A. MnCO3

B. Fe(OH)2

C. Ag2SO4

D.Ni(CN)2

Write the expression for K in terms of the solubility ,s, for each salt when dissolved in water. Example : 4s^2 or s^2

Barium sulfite_____

Magnesium hydroxide _____

Answer 1

Barium sulfite = BaSO3

BaSO3 -----> Ba²⁺ + SO3^2-

so salt that can be compared with it will be, A

MnCO3----> Mn²⁺ + CO3^2-

2.Magnesium Hydroxide = Mg(OH)2

Mg(OH)2 ----> Mg²⁺ + 2OH^-

so salt that can be compared with it will be B and D

B.Fe(OH)2 ----> Fe²⁺ + 2OH^-

D.Ni(CN)2 ----> Ni²⁺ + 2CN^-

Expression for K

barium sulfite-

BaSO3----> Ba²⁺ + SO3^2-

s s

so, K = [Ba²⁺][SO3^2-] = s.s = s²

Magnesium hydroxide

Mg(OH)₂---> Mg²⁺ + 2OH^-

s 2s

K = s.(2s)² = s.4s² = 4s³