A gas balloon has a volume of 160.0 L when the temperature is 45.0 C. and the pressure is 740.0 mm of mercury. What will its volume be at 20.0 C and 780.0 mm of mercury pressure? The answer is 92.6 L. Show your work of setting up and solving.

2 answers

The gas law is P1V1/T1 = P2V2/T2. Just plust in the numbers and solve for the only unknown. Be sure to convert T from Celsius to kelvin.
P1 = 740 mm Hg
V1 = 160.0 L
T1 = 45.0 C = 273 + 45.0 = ? kelvin
P2 = 780 mm Hg
V2 = ?
T2 = 20 C = 273 + 20 = ? kelvin
Solve for V2 in L. Post your work if you get stuck or don't understand something.
PV/T is constant, so you want V such that
780V/(273+20) = 740*160/(273+45)
I don't get 92.6

Is there something else at work here?