A gas of mass 32 gms has a volume of 20 litres at S.T.P .Calculate the gram molecular weight of the gas.

Step 1. Mass of gas = 32 gms

Volume of gas = 20 litres at S.T.P

Step 2. The mass of 22.4 litres of gas at S.T.P is equal to its gram molecular mass.

Step 3. 20 litres of gas at S.T.P weights = 32 gm

Then, 22.4 litres of gas will weight

$=\frac{32}{20}\times 22.4$

$=35.84\mathrm{gm}$

Therefore, Gram molecular weight of the gas is 35.84 gm.