Aweather balloon is filled with helium that occupies a volume of 5.57 104 l at 0.995 atm and 32.0°c. after it is released, it rises to a location where the pressure is 0.720 atm and the temperature is -14.5°c. what is the volume of the balloon at that new location?

6.52 × 10⁴ L. (3 sig. fig.)

Helium is a noble gas. The interaction between two helium molecules is rather weak, which makes the gas rather "ideal."

Consider the ideal gas law:

,

where

The question is asking for the final volume of the gas. Rearrange the ideal gas equation for volume:

.

Both the temperature of the gas, , and the pressure on the gas changed in this process. To find the new volume of the gas, change one variable at a time.

Start with the absolute temperature of the gas:

The volume of the gas is proportional to its temperature if both and stay constant.

.

Now, keep the temperature at and change the pressure on the gas:

The volume of the gas is proportional to the reciprocal of its absolute temperature if both and stays constant. In other words,

(3 sig. fig. as in the question.).

See if you get the same result if you hold constant, change , and then move on to change .