Question

In water saturated air, the mole fraction of water vapour is 0.02. If the total pressure of the saturated air is 1.2 atm, the partial pressure of dry air is ______.

Options

• 0.98 atm

• 1.18 atm

• 1.76 atm

• 1.176 atm

Answer 1

In water saturated air, the mole fraction of water vapour is 0.02. If the total pressure of the saturated air is 1.2 atm, the partial pressure of dry air is 1.176 atm.

Explanation:

Given: Mole fraction of water vapour = 0.02

Total pressure of saturated air = 1.2 atm

By using Dalton’s law of partial pressure, 

`P_"water" = chi_"water" * P_"total"`

= 0.02 × 1.2

= 0.024 atm

`P_"dry air" = P_"total" - P_"water"`

= 1.2 − 0.024

= 1.176 atm