Question

What will be the pressure of the gaseous mixture when 0.5 L of H2 at 0.8 bar and 2.0 L of dioxygen at 0.7 bar are introduced in a 1L vessel at 27°C? 

Answer 1

From the equation Pv = n RT for the two gases. We can write

0.8 x 0.5 = n_H2 x RT  or n_H2  = 0.8 x 0.5 / RT

ALSO  0.7 x 2.0  = n₀₂ . RT  or n₀₂  = 0.7 x 2 / RT

When introduced in 1 L vessel, then

Px1L = (n₀₂ + n_H2)  RT

Putting the values, we get

P = 0.4 + 1.4 = 1.8 bar

Hence, the total pressure of the gaseous mixture in the vessel is 1.8 bar

Answer 2

Let the partial pressure of H2 in the vessel be P_h2.