Question

The vapour density of ${\mathrm{CO}}_2$ gas is 22 . Find its molecular mass

Answer 1

Part 1: Molecular mass:-

The collective atomic masses of all atoms present in a molecule altogether is called the molecular mass.

Part 2: Vapour density:-

Vapour density is the density of a gas given in terms of the mass of 1 molecule of substance(gas) divided by the mass of 2 atoms of hydrogen at STP. $\frac{\mathrm{Mass}\mathrm{of}1\mathrm{molecule}\mathrm{of}\mathrm{substance}\left(\mathrm{gas}\right)}{\mathrm{Mass}\mathrm{of}2\mathrm{atoms}\mathrm{of}\mathrm{hydrogen}}$

Therefore, the relative molecular mass $=2\times \mathrm{vapour}\mathrm{density}$

Part 3: Calculating the molecular mass of ${\mathrm{CO}}_2$:-

The molecular of ${\mathrm{CO}}_2$is

$$\begin{gathered} =2\times \mathrm{vapour}\mathrm{density} \\ =2\times 22(\because \mathrm{vapour}\mathrm{density}=22) \\ =44\mathrm{g} \end{gathered}$$

Hence, the molecular mass of ${\mathrm{CO}}_2$having a vapour density of 22 is $44\mathrm{g}$.