If 1 gram of each of the following gases are taken at STP, which of the gases will occupy (a) greatest volume and (b) smallest volume? CO, H20, CH4, NO
Molar volume of a gas is volume occupied by 1 mole of gas at STP $(273.15$ $\mathrm{K}$ and 1 bar pressure) and is equal to $22700 \mathrm{~mL}$
$28 \mathrm{~g}$ of $\mathrm{CO}$ occupy volume $=22700 \mathrm{~mL}$
$\therefore 1 \mathrm{~g}$ of CO occupies volume $=\frac{22700}{28} \mathrm{~mL}$ at STP
Similarly,
$1 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$ occupies volume $=\frac{22700}{18} \mathrm{~mL}$ at STP
$1 \mathrm{~g}$ of $\mathrm{CH}_{4}$ occupies volume $=\frac{22700}{16} \mathrm{~mL}$ at STP
$1 \mathrm{~g}$ of $\mathrm{NO}$ occupies volume $=\frac{22700}{30} \mathrm{~mL}$ at STP
(a) $\mathrm{CH}_{4}$ occupies greatest volume.
(b) NO occupies smallest volume.