Question

A flask contains a mixture of N2 and O2 at STP. If the partial pressure exerted by the N2 is 40.0 kPa, the partial pressure of O2 is?

Answer 1

Answer: The partial pressure of
`O_2` is 61.325 kPa.

Explanation:

STP is the abbreviation for Standard Temperature and Pressure. The standard temperature is 273 K and the standard pressure is 1 atm pressure.

1 atm = 101.325 kPa

According to Dalton's law, the total pressure of a mixture of gases is the sum of individual pressures exerted by the constituent gases.

`p_(total)=p_A+p_B`

Thus
`p_(total)=p_(N_2)+p_(O_2)`

Given:

`p_(N_2)= 40 kPa`

`p_(total)=101.325kPa`

`101.325kPa=40kPa+p_(O2)`

`p_(O_2)=61.325kPa`

Answer 2

The partial pressure of O2 can be calculated by subtracting the total pressure with the partial pressure of N2 in the system. Therefore, the pressure of O2 would be 101.325 kPa - 40.0 kPa = 61.325 kPa. The total sum of all partial pressures should always equal to the total pressure of certain system.