Question

the weight of a substance that displaces 22.4 litre air at ntp is

Answer 1

According to Avocado's law :

22.4 litres of any gas = 1 mole.

Air has four components of gases:

Nitrogen = 78%

Oxygen = 21%

Argon = 1%

CO₂ = 0.03%

From one mole of air :

Nitrogen = 0.78 moles

Oxygen = 0.21 moles

Argon = 0.001 moles

CO₂ = 0.0003 moles


Their masses are :

Nitrogen = 28 (molecular mass of Nitrogen) × 0.78 = 21.84 grams

Oxygen = 32 (molecular mass of oxygen) × 0.21 = 6.72 grams

Argon = 39.948 (molecular mass of Argon) × 0.001 = 0.039948 grams.

The total mass of the air components is :

21.84 + 6.72 + 0.0132 + 0.039948 = 28.613grams

Mass of air displaced = mass of substance. = 28.613grams.

Weight = mass × gravitational acceleration

Convert mass to Kilograms.

28.613 / 1000 = 0.028613 kg

Weight = 0.028613 × 10 = 0.28613N

0.28613 N.