•     Tongs             • Table spoon

•     Oven mitten (or glove)                

*  Note: if ice is readily available in your classroom, add some to your water for an even more spectacular result

Instructions

           This very reliable and dramatic demonstration of atmospheric pressure will shock and amaze your students. A small amount of water boiled inside a soft drink can causes it to implode instantaneously when submerged into cold water. The loud crunch is echoed by a long “woooh!” followed closely by “do it again, do it again!”

1 Fill a bowl or jar almost to the brim with cold (if possible, refrigerated) water.

 Note: tap water works fine but colder water yields more spectacular results – use refrigerated or icy water if possible

3.    Use tongs to hold the soft drink can over the flame of a gas burner until the water boils (you’ll hear the water bubbling). Keep boiling the water for approximately 15 seconds.

 Note: hold the tongs with your wrist facing up as shown so you can invert the can in one smooth

        motion – you’ll need your spare hand to turn off the gas burner

4.    Turn off the flame with your spare hand, bring the can above the bowl of water, then turn it upside down submerge the hole into the cold water.

 Note: don’t turn the can over until it is over the bowl because the remaining water will spill – you will hear loud fizzing as the water inside the can runs down onto the hotter parts of the cane - you don’t need to

submerge the whole can in the water

This demonstration is safe if the common sense precautions associated with the use of a portable gas stove are observed. Discuss the safety precautions you are taking with your students and insist that they only attempt to repeat this demonstration under the supervision of an adult.

Teacher notes

The imploding can demonstrates several scientific concepts which are summarised below.