Question

Samples of the gases O₂, N₂, CO₂ and CO under the same conditions of temperature and pressure contain the same number of molecules x. The molecules of oxygen occupy V litres and have a mass of 8 g under the same conditions of temperature and pressure.

What is the volume occupied by:

1. x molecules of N₂,
2. 3x molecules of CO,
3. What is the mass of CO₂ in grams?
4. In answering the above questions, which law have you used?

Answer 1

Equal vols. of all gases under similar conditions of temperature and pressure occupy equal number of molecules.

(a) x molecules of nitrogen occupies vol. = V litres

(b) 3x molecules of CO gas occupy vol = 3 V litres

(c) x molecules of O₂ = `8/32= 1/4` molecule of O₂

∴ x molecules of CO₂ = `1/4` molecule of CO₂

∴ Mass of CO₂ present in the sample = `1/4 xx "gram molecular mass of CO"_2`

= `1/4 xx 44`

= 11 g

(d) Avogadro's Law.