Question

A gas mixture with a total pressure of 745 mmHg contains each of the following gases at the indicated partial pressures: CO2, 125 mmHg; Ar, 214 mmHg; and O2, 187 mmHg. The mixture also contains helium gas. What is the partial pressure of the helium gas? What mass of helium gas is present in a 12.0-L sample of this mixture at 273 K?

Answer 1

Answer:

$P_{He}=219mmHg$

$m_{He}=0.618gHe$

Explanation:

Hello,

By applying the Dalton's law, we can compute the partial pressure of the helium has:

$P_{tot}=P_{CO_2}+P_{Ar}+P_{O_2}+P_{He}$

Now, solving for the partial pressure of the helium gas we get:

$P_{He}=P_{tot}-P_{CO_2}-P_{Ar}-P_{O_2}=745mmHg-125mmHg-214mmHg-187mmHg\\P_{He}=219mmHg=0.288atm$

On the other hand, the mass of the helium gas is computed via the ideal gas equation in terms of the helium's mass:

$PV=\frac{m_{He}}{M_{He}}RT\\m_{He}=\frac{M_{He}PV}{RT} =\frac{4g/mol*0.288atm*12L}{0.082\frac{atm*L}{mol*K}*273K}\\ m_{He}=0.618gHe$

Best regards.