Calculate the solubility in mol dm-³ of 40g of CuSO4 dissolved in 100g of water at 120°C. [Cu = 64, S = 32, O = 16]

A. 4.00
B. 2.50
C. 0.40
D. 0.25

Correct Answer:

Option B – 2.50

Explanation

Solubility = number of moles of solution/vol of solution
100g of water = 100 cm³ = 0.1 dm³.

CuSO4 = 160g/mol

No of moles of CuSO4 in 40g = 40/160
= 0.25 mol.

Solubility = 0.25/0.1
= 2.5 moldm−³.