Question

A mixture of gases at 760 torr contains 55.0% nitrogen, 25.0% oxygen and 20.0% of carbon di oxide by mole.what is partial pressure of each gas in torr?

Answer 1

calculate total and then for each gas

Answer 2

Solution:

According to Dalton law of partial pressure of gases :

$p_a={P_T}\times X_a$

$p_a=\text{partial pressure of gas a},P_T=\text{total pressure},X_a=\text{mole fraction of gas 'a'}$

$P_T= \text{total pressure}=760 torr$

Mole fraction of nitrogen gas,$X_{N_2}=55.0\%=\frac{55.0}{100}=0.55$

Mole fraction of oxygen,$X_{O_2}=25.0\%=\frac{25.0}{100}=0.25$

Mole fraction of carbon-dioxide,$X_{CO_2}=20.0\%=\frac{20.0}{100}=0.20$

Partial pressure of nitrogen gas,$p_{N_2}=P_T\times X_{N_2}=760\times 0.55=418 torr$

Partial pressure of oxygen,$p_{O_2}=P_T\times X_{O_2}=760\times 0.25=190 torr$

Partial pressure of carbon dioxide,$p_{CO_2}=P_T\times X_{CO_2}=760\times 0.20=152 torr$