I need help with chemistry please!!???

Question

we were doing a lab today and i got stumped by this:
when you heat a can over a flame for a few seconds and then put it into a tray with water, why does the water get sucked into the can when before, when not heated, it floated??

Answer 1

The air in the can got hot and expanded out of the can. When put in cold water the air left in the can contracted and made a lower pressure area. The water outside the can rushed into the can to equalize the pressure. This does not happen unless there is a difference in pressure such as the one caused by heating the can/air.