General Chemistry I
posted by Emily .
A sample of gas occupies a volume of 59.9 mL. As it expands, it does 126.2 J of work on its surroundings at a constant pressure of 798 torr. What is the final volume of the gas?
a. 61.1 mL
b. 1,250 mL
c. 218 mL
d. 1,490 mL
e. None of the above
I used the work function w = -PΔV and I performed the following conversions:
-126.6 J = -1.2458 L*atm
798 torr = .9524 atm
I plugged these values in to the equation:
-1.2458 L*atm = (.9524 atm)(ΔV)
ΔV = 1.30806 L
I then added the original volume of 59.9 mL to this value to get around 1,367 mL for the final volume, but this is apparently incorrect. I found if I subtracted 59.9 mL from 1.30806 L I got the correct answer, but I didn't know if this was the proper way to reach the answer.
So long story short, is subtracting the value of the original volume from ΔV correct, and if so, why?