Question

A sample of NaNO3 was fully decomposed into its elements, and the resulting gas was collected over water at 34°C. If the total pressure of the collected gas was 760 torr, and the vapor pressure of water at 34°C is 40.0 torr, what was the partial pressure of N2 gas in the flask?

Answer 1

Answer is: the partial pressure of nitrogen gas is 720.0 torr.

The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture.

p(mixture) = p(water) + p(nitrogen).

p(water) = 40.0 torr; partial pressure of the water.

p(nitrogen) = p(mixture) - p(water).

p(nitrogen) = 760.0 torr - 40.0 torr.

p(nitrogen) = 720.0; patial pressure of N₂.