Question

Total pressure of a mixture of H2 and O2 is 1.00 bar. The mixture is allowed to react to form water, which is completely removed to leave only pure H2 at pressure of 0.35 bar. Assuming ideal gas behaviour and that all pressure measurements were made under the same temperature and volume conditions, the composition of the original mixture is

Answer 1

Oxygen- hydrogen composition in original mix was:

0.21667 bar O2 and 0.78333 bar H2

•Avagadro's Law says:

Equal volume of two gases at same pressure and temperature conditions have equal number of molecules.

•1 O2 molecule consumes 2 H2 molecules.

•Since after the reaction only H2 is left, we know all of O2 is consumed.

•This implies what all is consumed 1/3 of it was O2.

Hence, O2 in the mix was at a partial pressure of

(1 - 0.35) 1/3

→ 0.21667

And rest was H2

Hence oxygen- hydrogen composition in original mix was:

0.21667 bar O2 and 0.78333 bar H2.