Question

What is the approximate mass of $1$ litre of nitrous oxide, $N_{2}O$, at $STP$ ? (Answer in grams)

• A. $1$
• B. $2$
• C. $11.2$
• D. $22$
• E. $44$

Answer 1

The correct option is B $2$

At $STP$, 1 mole of nitrous oxide occupies a volume of 22.4 $L$.
The atomic masses of $N$ and $O$ are 14 $g/mol$ and 16 $g/mol$ respectively.
The molar mass of nitrous oxide
$N_{2}O=2\left(14\right)+16=44$ $g/mol$
Thus 44 $g$ (1 mole) $N_{2}O=$ 22.4 $L$ at $STP$.
$1L$ $N_{2}O=\frac{44}{22.4}=2$ $L$