A helium balloon is filled to a volume of 2.88 x 103 L at 722 mm Hg and 19°C. When the balloon is released, it rises to an altitude where the pressure and temperature are 339 mm Hg and -55oC, respectively. What is the volume of the balloon (in L)?

Answer 1

Since PV/T is constant, you want V such that
(339*V) / (273-55) = (722 * 2.88*10^3) / (273+19)