When the balloon is rubbed on a pair of jeans, electrons are wiped from the jeans to the balloon, causing a net negative charge on the balloon. The charged balloon is held near a thin stream of water. Charges in the water rearrange so that the positive charges in the water become attracted to the negatively charged balloon, and the stream of water bends. The rearranging of charges is pronounced because water is a polar molecule.
When ammonium nitrate is dissolved in water it feels cold, which indicates an endothermic reaction.
NH4NO3 (s) → NH4+ (aq) + NO3- (aq)
This demo simulates what happens when Drano is poured down a clogged drain; the hydrogen gas produced forces gunk out of the drain. Also, this demonstration is a good safety example of why bases need to be handled carefully – they can be corrosive, especially to metals. If the hydrogen gas is collected and ignited, this demo shows the safety hazards that evolved gases can have.
2Al + 2NaOH + 6H2O → 2NaAl(OH)4 + 3H2