Question

If 2.38 mol of a gas has a volume of 120.0 mL, what is the volume of 1.97 mol of the gas at the same temperature and pressure?

Answer 1

According to the Avogadro's law, equal volumes of all gases contain equal number of moles under the same conditions of temperature and pressure.

Here the initial volume, $V_{1} = 120.0 mL$

Initial moles of the gas, $n_{1}=2.38 mol$

Final volume of the gas $V_{2} = ?$

Final moles of the gas $n_{2}= 1.97 mol$

Plugging in the Avogadro's equation,

$\frac{V_{1}}{n_{1}} = \frac{V_{2}}{n_{2}}$

$\frac{120.0 mL}{2.38 mol} = \frac{V_{2}}{1.97 mol}$

$V_{2} = 99.33 mL$

Therefore the 1.97 mol of the gas occupies 99.33 mL at constant temperature and pressure.