Question

Equal volumes of ammonia gas and chlorine gas are kept in two different containers under the same conditions of temperature and pressure. Find the number of molecules contained in chlorine gas when the mass of ammonia is 34 g. [Atomic weight: C1 = 35.5, H = 1, N = 14]

Answer 1

Given: Mass of ammonia = 34 g

Atomic weight of Nitrogen (N) = 14

Atomic weight of Hydrogen (H) = 1

Equal volumes of gases at the same temperature and pressure contain an equal number of molecules.

So, number of molecules in NH₃ = number of molecules in Cl₂

Molar Mass of NH₃ = 14 + (3 × 1)

= 17 g/mol

Number of moles = `"Mass"/"Molar mass"`

Moles of NH₃ = `(34 "g")/(17 "g/mol")`

= 2 moles

Number of molecules = Moles × Avogadro’s number

= 2 × 6.023 × 10²³

= 1.2046 × 10²⁴