How many liters of hydrogen will be released when 72 g of water is decomposed by electric current?

The problem is solved according to the reaction equation:

2H2O → 2H2 ↑ + O2 ↑.

The molar mass of water is M (H2O) = 2 × Ar (H) + Ar (O) = 2 × 1 + 16 = 18 g / mol.

The amount of water n (H2O) = m (H2O): M (H2O) = 72: 18 = 4 mol.

According to the reaction equation, from 2 moles of water, 2 moles of hydrogen are obtained (seen by the coefficients in front of the formulas of these substances in the reaction equation). This means that 4 moles of water were formed from 4 moles of hydrogen. We find the volume of hydrogen by the formula:

V (H2) = n (H2) × V m (H2) = 4 × 22.4 = 89.6 liters.