A 500. mL sample of hydrogen gas is collected over water at 27 °C. The pressure of the hydrogen and water vapor mixture is 78.5 kPa and the vapor pressure of water at 27 °C is 3.6 kPa. What is the partial pressure of the dry hydrogen gas?

Answer 1

Ptotal = pH2dry + pH2O
You know Ptotal and pH2O, solve for pH2 dry.

Answer 2

Khud Marlo yaar