At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

Question

Philoid · Accepted Answer

Density (d) of the substance at temperature (T) can be given by the expression,

⇒

Now, density of oxide (d₁) is given by,

⇒

Where, M₁ and P₁ are mass and pressure of the oxide respectively.

Density of dinitrogen gas (d₂) is given by,

⇒ d₂ =

Where,M₂ and P₂ are the mass and pressure of the oxide respectively.

According to the given question,

⇒ d₁ = d₂

Molecular mass of nitrogen, M₂ = 28 g/mol

⇒ M₁P₁ = M₂P₂

Therefore, we can write

Hence molar mass

⇒

⇒ M = 70 g/mol

Hence, the molecular mass of the oxide is 70 g/mol