Question

If the vapor pressure of water (
`P_(H_2O)`) at 20.0°C is 17.5 mm Hg, and the atmospheric pressure measured by a barometer (
`P_(total)`) was 757.3 mm Hg, what is the partial pressure of H₂ gas (
`P_(H_2)`) in the gas mixture in a buret? (Use Dalton’s Law of Partial Pressures to solve for
`P_(H_2)`)

Answer 1

739.8 mmHg

Step-by-step explanation:

By Dalton's Law of Partial Pressures, the total pressure of a gas mixture is the sum of the partial pressure of its components. The partial pressure is the pressure that the substance would have if it was alone in the same conditions of the mixture (same temperature and volume). So:

`P_(total) = P_{H_(2)O} + P_{H_(2)}`

757.3 = 17.5 +
`P_{H_(2)}`

`P_{H_(2)}` = 757.3 - 17.5

`P_{H_(2)}` = 739.8 mmHg