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?

Question

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?

Answer 1

And according to this solution I have here the correct answer is b. 1,250 mL~

Answer 2

Never mind, I just found my error; I incorrectly converted between Torr and atm, I should've gotten 1.05 atm instead.