posted by Lupe .
The total pressure in a vessel containing hydrogen collected over water at 25.0°C was 0.8 atm. The vapor pressure of water at that temperature is 23.8. what was he pressure of the oxygen in torr?
Ptotal = pO2 + pH2O
I would convert 0.8 atm to torr, substitute into Ptotal and solve for pO2 (in torr).