A balloon is filled with 1.50 L of helium gas at sea level, 1.00 atm and 32ºC. The balloon is released and it rises to an altitude of 30,000 ft. If the pressure at this altitude is 228 mm Hg and the temperature is -45ºC, what is the volume of the balloon?
NEED EXPLANATION/WORK

The particle density of atmospheric air at 273.15 K at sea level is 2.687*1025/m3.  Calculate the pressure P.

Solution:

   Reasoning:

   The ideal gas law, PV = NkBT, P = (N/V)kBT = ρparticlekBT.

   Details of the calculation:

   P = (2.687*1025/m3)(1.381*10-23 Pa m3/K)(273.15 K) = 1.01*105 Pa  = 101 kPa.

Problem:

If a helium-filled balloon initially at room temperature is placed in a freezer, will its volume increase, decrease, or remain the same?

Solution:

   Reasoning:

   The ideal gas law states that PV/T is constant.  The pressure in the freezer is atmospheric pressure, the temperature in the freezer is lower that the outside temperature, so the volume of the balloon decreases when it is placed into the freezer.

Explanation:

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.