Hot-Air Balloon Physics Fun Facts!

How does heating the air inside a hot-air balloon affect the number of moles of air present?

When a hot-air balloon is heated, what happens to the number of moles of air inside?

Answer:

Heating the air inside a hot-air balloon actually causes the number of moles of air present to decrease!

When the air of a hot-air balloon is heated, the density decreases, causing the molecules inside the balloon to occupy a larger volume. Some molecules flow out of the balloon to make room for the remaining molecules, resulting in a slight decrease in the number of moles of air present after heating compared to the original number. This decrease in moles helps create buoyancy for the balloon!

The ratio of the number of moles in the heated balloon to the original number of moles is less than 1, reflecting the decrease in moles due to expansion upon heating.