On a hot day, a child drinks all the water in a plastic bottle. She then screws the cap back tightly on the bottle, so that the bottle contains only air. She throws the
bottle into a wastebasket, where the Sun shines on it. After a while in the Sun's rays,
the air in the bottle is much hotter than before.
cap screwed on
(i) State what has happened to the pressure of the air in the bottle.
Give a reason for your answer.
(ii) In terms of the behaviour of the air molecules, explain your answer
to a(i)

1. The pressure of air in the bottle increased.

2. When the air in the bottle gets hot the air also expands. like all molecules they are always moving but the air inside the bottle moves a lot. The air molecules bump and crash into one another and on the bottle’s inner walls. The hotter the air gets the more moving and bumping occurs which I turn increase the pressure. Say you continue to apply heat to the bottle. If this is true the bottle will either explode or the threads of the bottle cap and bottle will give way for the air to escape.