Question

The weight of $1\times {10}^{22}$ molecules of $CuS{O}_4\cdot 5H_{2}O$ is:

(nearest integer)

Answer 1

Weight of $6.023\times {10}^{23}$ molecules $=$ Molecular weight of $CuS{O}_4\cdot 5H_{2}O=249g$ $=$ $1$ mol of $CuS{O}_4\cdot 5H_{2}O$

Weight of $1\times {10}^{22}$ molecules of $CuS{O}_4\cdot 5H_{2}O$ $=\frac{249\times 1\times {10}^{22}}{6.023\times {10}^{23}}=4.13g$ $\approx$ $4$