The drain cleaner

The reaction of aluminium with caustic soda can be represented as:

At STP (273.15 K and 1 atm), 54 g (2 × 27 g) of Al gives 3 × 22400 ml of Hydrogen

⇒ 0.15 g Al gives i.e. 3×22400×0.15/54 = 186.67 ml of Hydrogen.

At STP,

Let the volume of dihydrogen V₂ be at p₂ = 0.987 atm (since 1 bar = 0.987 atm) and T₂ = 293.15K.

⇒ 20°C = (273.15 + 20) K = 293.15 K.

⇒ = constant

So,

⇒

⇒ V₂ = 203ml

Therefore, 203 ml of dihydrogen will be released.