Weight of Air Apparatus

Convince your students that air has weight with this fun demonstration apparatus. Simply weigh the can with air trapped inside. Then connect the demonstration apparatus to a vacuum pump and pump the air out of the can. The convenient built-in valve makes this very easy to do. With the can emptied of air weigh it again. The approximate 0.5-gram difference will be dramatic. Calculate the volume inside the cylinder and calculate the weight of air per liter!