(i) Using the formula density = mass/volume, explain what will be the effect of heat on the gas kept in a closed bottle.

Question

Expansion of gases:

A gas does not even have a fixed volume. Gas expands on heating but if the gas is kept in a closed box, its volume cannot increase but its pressure increases. This is shown in Fig. Observe Fig. and find out answers to the questions.

(i) Using the formula density = mass/volume, explain what will be the effect of heat on the gas kept in a closed bottle.

(ii) If the bottle is not closed but has a movable piston attached to its open end (see the figure), what will be the effect of heating the gas in the bottle?

Answer 1

(i) The density of the gas will remain the same as there is no change on the mass and volume of the gas.

(ii) The piston will move upwards as the gas expands. Therefore, the expansion of a gas is measured by keeping its pressure constant.