Question

The total pressure is 600 mmHg after 0.50 moles of nitrogen gas, `N_2`, and 1.0 mole of nitrogen dioxide, `NO_2`, gas are mixed in a closed container. There is no reaction between the gases. What is the partial pressure of the nitrogen dioxide?

Answer 1

`P_(NO_2)=400*mm*Hg`

Explanation:

Old `"Dalton's Law of partial pressures"` tells us that in a gaseous mixture, the partial pressure exerted by a component gas is the same as the pressure it would exert if it ALONE occupied the container.

The total pressure is the sum of the individual partial pressures.

Thus `P_"Total"=P_(NO_2)+P_(N_2)=600*mm*Hg`

But `P_(NO_2)=(1.0*molxxRT)/V`

And `P_(N_2)=(0.50*molxxRT)/V=1/2xxP_(NO_2)`

And so `P_"Total"=600*mm*Hg=3/2xxP_(NO_2)`

And finally, `P_(NO_2)=400*mm*Hg`, and `P_(N_2)=200*mm*Hg`; the which satisfies Dalton's Law....