Question

A mixture of 14.0 grams of H2, 84.0 grams of N2, and 64.0 grams of O2 are placed in a flask. The partial pressure of the O2 is 78.00 torr. What is the total pressure in the flask

Answer 1

Answer:

$P_{tot}=465.27torr$

Explanation:

Hello there!

In this case, according to the given information, it will be possible for us to use the Dalton's law, in order to solve this problem. However, we first need to calculate the mole fraction of oxygen by firstly calculating the moles of each gas:

$n_{H_2}=\frac{14.0g}{2.02g/mol} =6.93mol\\\\n_{N_2}=\frac{84.0g}{28.02g/mol}=3.00mol\\\\n_{O_2}=\frac{64.0}{16.00g/mol} =2.00mol$

Next, we calculate such mole fraction as follows:

$x_{O_2}=\frac{2}{6.93+3+2} =0.168$

Then, given the following equation:

$P_{O_2}=P_{tot}*x_{O_2}$

So we solve for the total pressure as follows:

$P_{tot}=\frac{P_{O_2}}{x_{O_2}} \\\\P_{tot}=\frac{78.00torr}{0.168} \\\\P_{tot}=465.27torr$

Regards!