Chemistry pressure exerted by different substances at a constant temperature

Question

A 20.0–L tank at a temperature of 27 ℃ contains a mixture of 3.5 moles of oxygen and 6.0 moles of hydrogen. Find the partial pressure exerted by each gas and then complete the equation below to determine the total pressure inside the tank.

P(oxygen) + P(hydrogen) = Total pressure in tank

Answer 1

Hello, Jacob,

This requires use of the ideal gas law PV = nRT. Pressure times Volume is equal to the moles * (gas constant R)*(Temperature in K).

I chose a gas constant with units consistent with the data. Also, C needs to be converted to K.

First, I calculated the pressures of the individual gases. Just plug the numbers into the ideal gas law equation, and make sure the units cancel as expected.

I first calculated the total pressure by adding the moles of O₂ and H₂, for 9.5 moles total. The system pressure is 11.7 atm.

Two separate calculations are needed to arrive at an O₂ partial pressure of 4.31atm and an H₂ partial pressure of 7.38atm. This sums to 11.7atm, as expected.

There are only 2 sig figs in the moles, so use that number in the final answers.

Bob