Question

Find the mass of $29.12\text{L}$ of $S{O}_3$ gas at STP.

• A. $83.2\text{g}$
• B. $63.9\text{g}$
• C. $28.4\text{g}$
• D. $104\text{g}$

Answer 1

The correct option is D $104\text{g}$

1 mole of $S{O}_3$ occupies 22.4 L at STP.
$29.12\text{L}$ will be occupied by $\frac{1}{22.4}\times 29.12=1.3$ moles of $S{O}_3$
$\text{Mass of}S{O}_3=\text{number of moles}\times \text{molar mass}=1.3\times 80=104\text{g}$