Question

The pressure and temperature of mixture of 4 kg O₂ and 6 kg N₂ are 4 bar and 27°C. What will be the value of molecular weight of mixture?

1. 40.67
2. 39.87
3. 29.47
4. None of the above

Answer 1

Correct Answer - Option 3 : 29.47

Concept:

\({{\rm{M}}_{{\rm{mix}}}} = \frac{1}{{\frac{{{{\rm{X}}_1}}}{{{{\rm{M}}_1}}} + \frac{{{{\rm{X}}_2}}}{{{{\rm{M}}_2}}}}}\)

Where,

M_mix = Molecular weight of the mixture.

X₁, X₂ = Mass fraction of oxygen and nitrogen.

Mass fraction = The mass fraction is the ratio of the mass of a component in the mixture to the total mass of the mixture. 

M₁, M₂ = Molecular weight of oxygen and nitrogen.

Calculation:

Given:

Mass of oxygen and nitrogen is 4 kg and 6 kg.

∴ \({{\rm{X}}_1} = \frac{4}{{10}} = 0.4,\;{{\rm{X}}_2} = \frac{6}{{10}} = 0.6\;\)

M₁, M₂ = 32, 28.

By using the above formula

\({{\rm{M}}_{{\rm{mix}}}} = \frac{1}{{\frac{{0.4}}{{32}} + \frac{{0.6}}{{28}}}} = 29.47\)