How many grams of oxygen are collected in a reaction where 247 mL of oxygen gas is collected over water at a temperature of 25°C and a total pressure of 697 torr? And would i just convert 697 torr into atm and use that for pressure? And how do i find the molar mass of the problem?

Answer 1

I think I worked through this earlier.
First you need to determine the gas pressure less the water vapor.
Ptotal = pO2 + pH2O
697 = pO2 -vapor pressure H2O @ 25C.
Then convert pO2 to atm (divide by 760).
Then use PV = nRT and solve for n = number of mols. Finally,
n = grams/molar mass. You know n and grams, solve for molar mass.