A balloon containing helium gas has a volume of 1.25 L at room temperature (23 oC). The balloon is heated to at temperature of 85 oC . Assuming no change in pressure, what is the new volume of the balloon?

Explanation:

The pressure stays constant, so we are dealing with volume and temperature, so we use Charles's Law. This states the temperature and volume of a gas are directly proportional. The formula is:

We know the original balloon has a volume of 1.25 liters at a temperature of 23 degrees celsius. These values can be substituted in.

The new volume is unknown, but the temperature is increased to 85 degrees Celsius.

We are trying to solve for the new volume, V₂. It is being divided by 85 degrees Celsius. The inverse of division is multiplication, so we multiply both sides by 85°C.

The units of degrees Celsius cancel.

The original measurements have at least 2 significant figures, so our answer must have 2. For the number we found, that is the tenth place.

The 1 in the hundredth place (in bold above) tells us to leave the 6 in the tenth place.

The new volume of the balloon is approximately 4.6 liters.