a student collects a sample of hydrogen gas over water when the atmospheric pressure is 99.4kpa and the temperature is 23.0C what is the pressure of the hydrogen gas?

Given:

Atmospheric pressure = 99.4 kPa

Temperature = 23 C

To determine:

The pressure of H2 gas collected over water

Explanation:

Based on Dalton's Law of partial pressures

P (total) = P (water) + P (H2)

PH2 = Ptotal - Pwater

where: Ptotal = atmospheric pressure = 99.4 kPa

Pwater = vapor pressure of water at 23 C = 2.81 kPa

PH2 = 99.4 - 2.81 = 99.59 kPa

Ans: The pressure of H2 gas is 99.6 kPa