Question

A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 42.9 kPa. What is the partial pressure of carbon dioxide if the partial pressure of oxygen is 6.6 kPa and the partial pressure of nitrogen is 23.0 kPa?

Answer 1

The total Pressure equals the sum of all pressures contained 

Since total pressure and the pressure of nitrogen and oxygen is given, finding the pressure of carbon dioxide is given by: 

Pressure of Carbon dioxide = 42.9- 6.6- 23.0 
=13.3kPa 

Answer 2

Answer : The partial pressure of the carbon dioxide gas is, 13.3 kPa

Solution :

According to the Dalton's law of partial pressures, the total pressure of an ideal gas mixture is equal to the sum of the partial pressures of the gases in the mixture.

$P_T=P_{O_2}+P_{N_2}+P_{CO_2}$

where,

$P_T$ = total pressure = 42.9 kPa

$P_{O_2}$ = partial pressure of oxygen gas = 6.6 kPa

$P_{N_2}$ = partial pressure of nitrogen gas = 23.0 kPa

$P_{CO_2}$ = partial pressure of carbon dioxide gas = ?

Now put all the given values in the above formula, we get the partial pressure of carbon dioxide gas.

$42.9=6.6+23.0+P_{CO_2}$

$P_{CO_2}=13.3kPa$

Therefore, the partial pressure of the carbon dioxide gas is, 13.3 kPa