Question

1. choose the best answer. which compound contains the highest percent composition of copper? $\ce{cu2so4}$ $\ce{cuso4}$ $\ce{cuso3}$ $\ce{cu2so3}$

Explanation:

Step1: Get molar masses

Molar mass of Cu = $63.55\ \text{g/mol}$, S = $32.07\ \text{g/mol}$, O = $16.00\ \text{g/mol}$

Step2: Calculate %Cu for $\text{Cu}_2\text{SO}_4$

Total mass: $2\times63.55 + 32.07 + 4\times16.00 = 223.17\ \text{g/mol}$
$\%Cu = \frac{2\times63.55}{223.17} \times 100\% \approx 57.0\%$

Step3: Calculate %Cu for $\text{CuSO}_4$

Total mass: $63.55 + 32.07 + 4\times16.00 = 159.62\ \text{g/mol}$
$\%Cu = \frac{63.55}{159.62} \times 100\% \approx 39.8\%$

Step4: Calculate %Cu for $\text{CuSO}_3$

Total mass: $63.55 + 32.07 + 3\times16.00 = 143.62\ \text{g/mol}$
$\%Cu = \frac{63.55}{143.62} \times 100\% \approx 44.3\%$

Step5: Calculate %Cu for $\text{Cu}_2\text{SO}_3$

Total mass: $2\times63.55 + 32.07 + 3\times16.00 = 207.17\ \text{g/mol}$
$\%Cu = \frac{2\times63.55}{207.17} \times 100\% \approx 61.2\%$

Step6: Compare percentages

$61.2\% > 57.0\% > 44.3\% > 39.8\%$

Answer:

$\text{Cu}_2\text{SO}_3$