Question

A sample of gas is collected over water at a temperature of 35.0◦C when the barometric pressure reading is 642 torr. What is the partial pressure of the dry gas, given PH2O = 42.2 torr? Answer in units of torr.

Answer 1

Answer: The partial pressure of the dry gas is 599.8 torr

Explanation:

According to Dalton's law, the total pressure is the sum of individual pressures.

$p_{total}=p_{dry gas}+p_{H_2O}$

Given : $p_{total}$ =total pressure of gases = 642 torr

$p_{dry gas}$ = partial pressure of dry gas = ?

$p_{H_2O}$ = partial pressure of water = 42.2 torr

putting in the values we get:

$642torr=p_{\text {dry gas}}+42.2torr$  

$p_{\text {dry gas}}=599.8torr$

Thus the partial pressure of the dry gas is 599.8 torr