Question 4 of 10
A sample of a hydrate of copper(II) sulfate is found to contain 36.08% by mass
water. What is the formula of the hydrate?
A) CuSO, 2 H,0
B) CuSO4-5 H2O
C) CuSO4.5H2O
D) CuSO43 H2O

The correct answer to the question is option C. CuSO₄.5H₂O

We'll begin by calculating the percentage of CuSO₄ in the compound. This can be obtained as follow:

H₂O = 36.08%

CuSO₄ = 100 – H₂O

CuSO₄ = 100 – 36.08

Finally, we shall determine the formula of the compound. This can be obtained as follow:

Molar mass of CuSO₄ = 159.55 g/mol

Molar mass of H₂O = 18 g/mol  

CuSO₄ = 63.92%

H₂O = 36.08%

Divide by their molar mass

CuSO₄ = 63.92 / 159.55 = 0.4

H₂O = 36.08 / 18 = 2

Divide by the smallest

CuSO₄ = 0.4 / 0.4 = 1

H₂O = 2 / 0.4 = 5

Therefore, the formula of the compound is CuSO₄.5H₂O.

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