chemistry
posted by Andrew78 on .
50 ml of Argon is collected at 60.0 degree C and 820.0 torr how much this sample weigh in grams?

Use PV = nRT and solve for n = number of mols. Then n = grams/molar mass and solve for grams. Don't forget T must be in kelvin.

do I need to consider the vapor pressure of Argon at 60.0 degree C

I don't understand your question. The pressure of Ar in the flask is 820 torr. I guess we could call that its vapor pressure.
Remember to convert 820 torr to atm and T to kelvin. 
my instructor said we need to use the pressure due to water vapor. i'm confused

Then you didn't post all of the problem. The problem you posted doesn't have any water in it. If you collected the Ar over water and the total pressure is 820 torr, then
Ptotal = 820 = pAr + pH2O
Look up vapor pressure H2O at 60.0 C and subtract from 820 to find pAr.
Then follow the instructions above.
T must be in kelvin
P must be in atm (for PV = nRT)
V must be in L.