Question

Amount of oxygen in $32.2g$ of $N{a}_{2}S{O}_4.10H_{2}O$ is:

• A. $20.8g$
• B. $22.4g$
• C. $2.24g$
• D. $2.08g$

Answer 1

The correct option is B $22.4g$

The molar mass of $N{a}_{2}S{O}_4.10H_{2}O$ is
$2\left(23\right)+32+4\left(16\right)+10\left(18\right)=322$ g/mol.
1 mole of $N{a}_{2}S{O}_4.10H_{2}O$ contains 14 moles of O atoms.
1 mole of $N{a}_{2}S{O}_4.10H_{2}O$ corresponds to $14\times 16=224$ g of O.
Amount of oxygen in 32.2g of $N{a}_{2}S{O}_4.10H_{2}O$ is $32.2\times 224322=22.4$ g