Question

How can I calculate the molar volume of hydrogen gas?

Answer 1

Hint: Molar volume is the volume occupied by one mole of a gas. It is usually calculated at STP and a fixed volume.
- The easiest way to find the molar volume is by diving the molar mass by the mass density. This can be expressed as;
\[{{V}_{m}}=\dfrac{Molar~mass}{Density}\]

Complete step by step answer:
Let us see the way to calculate the molar volume of hydrogen;
- The molar volume of an ideal gas will be 22.4 litres at $0{}^\circ C$ and 1 atm. This will increase to 24 litres at $20{}^\circ C$ and 1 atm.
The actual molar volume of hydrogen gas can be calculated as;
Molar mass of hydrogen gas = 2.0159 g/mol
Experimental density = 0.0899 g/L at $0{}^\circ C$ and 1 atm.
Thus, molar volume will be;
${{V}_{m}}=\dfrac{2.0159g/mol}{0.0899g/L}=22.42L$
Similarly,
Experimental density = 0.0837 g/L at $20{}^\circ C$ and 1 atm.
The molar volume will be;
${{V}_{m}}=\dfrac{2.0159g/mol}{0.0837g/L}=24.08L$
Thus, we can see that the molar volume of hydrogen gas is nearly the same as that of ideal gas. Thus, hydrogen gas behaves as ideal gas.

Note: Experimentally, according to the mole concept of chemistry, one mole of any gas will occupy the volume of 22.4 litres at STP i.e.
1 mole of gas at STP = 22.4 litres of gas
- Molar volume of gas can help us determine the volume of gas as volume of a gas will be the product of amount of gas in moles and molar volume i.e.
Volume = amount (in moles) $\times $ molar volume