Question

How many grams of CaC₂O₄ will dissolve in distilled water to make one litre of saturated solution (K_sp = 6.25 × 10^–10 and its molecular mass is 128) : 

(A) 0.0064 g 

(B) 0.0128 g 

(C) 0.0032 g 

(D) 0.0640 g 

Answer 1

Correct option: (C) 0.0032 g

Explanation: 

[Ca²⁺] [C₂O₄^2–] = 6.25 × 10^–10 so solubility = 2.5 × 10^–5 mol/L = 2.5 × 128 × 10^–5 = 3.2 × 10^–3 g/L