Question

A sample of copper sulphate pentahydrate, $CuSO_4.5H_2O$ contains 3.782 g of Cu. How many grams of oxygen are in this sample ?

• A. 0.952 g
• B. 3.809 g
• C. 4.761 g
• D. 8.576 g

Answer 1

Answer: (D)

8.576 g

Answer 2

$CuSO_{4}\cdot5H_{2}O$ has $1$ mole of copper and $9$ moles of oxygen atoms $63.5\,g\, Cu \equiv 9 \times 16\,g$ of oxygen $3.782\,g\,Cu \equiv \frac{9\times16\times3.782}{63.5}$ $=8.576$ of oxygen