Boil water in a can until steam has driven out the air present inside the can. Remove the can from the flame and place the stopper immediately. When cold water is poured over the can, it is observed that the can collapses inward. Which of the following is the correct reason for it? a)Pressure inside the can is less than the pressure outside it. b)The temperature inside the container is less than the outside temperature. c) Pressure inside the can is equal to the pressure outside it. d) Pressure inside the can is more than the pressure outside it.
Answers
Answer:
Put about two tablespoons of water in an empty aluminum can. Set the can on a stove burner or over a flame until the the water in the can turns to steam. Use an oven mitt or tongs to carefully remove the steaming can from the heat source and immediately turn the can upside down into a bowl of cold water. The whole can does not need to be submerged, just the lip around the open end will do. The can will loudly implode.
If one is available, use a can that has already has the word "Crush" on it.
Explanation
This demonstrates phase change and the effect of unbalanced pressure. When the water in the can is heated, it changes to steam. This steam fills the can, replacing most of the air that was inside of it. When the inverted can is placed in cold water, the steam condenses, leaving the can mostly empty, and thus with a very low pressure inside of it. The difference between the low pressure inside and the atmospheric pressure outside exerts an inward force on the walls of the can, causing it to implode.
(a) pressure inside the can is less than the pressure outside it