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Suppose 100mL of oxygen were collected over water in the laboratory at a pressure of 700 torr and 20 degree celsius. What would

Submitted by jjgermitano on Sun, 07/28/2013 - 10:09

Suppose 100mL of oxygen were collected over water in the laboratory at a pressure of 700 torr and 20 degree celsius. What would be the volume of the dry gas at STP?


Use Dalton's law and the vapor pressure of water at 20.0 o C to correct the pressure to units of atmoshperes.

PT = Poxygen +Pwater 
At 20.0 o C find out what is the vapor pressure of water(This can be found on a vapor pressure table.) 

PT = 700 torr 

put it in above equation to find the  Poxygen  and convert it to atmosphere.

now you have pressure of oxygen from above which is your P1 and T1 is 20 degree celsius convert it to kelvins and V1 is 100mL, to find volume at STP , P2 = 1 atm  and T2 = 273 K and V2 is what you need to find , use

P1V1/T1 = P2V2/T2

and find V2