Question

The diagram below shows the collection of H2 gas over water at 25°C. The total pressure in the tube is 760.0 torr. What is the pressure exerted by the hydrogen gas alone? (Hint: water vapor pressure = 23.8 torr @ 25°C)

Answer 1

Answer: 736.2 torr

Explanation: 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_(H_2O)+p_(H_2)`

Given:
`p_(total)=760 torr`

`p_(H_2O)=23.8torr`

`p_(H_2)= ?torr`

Thus
`760torr=23.8torr+p_(H_2)`

`p_(H_2)=736.2torr`

Thus pressure exerted by the hydrogen gas alone is 736.2 torr.