CHEMISTRY DEMONSTARTION

DISAPPEARING METAL

Aim: To show that bases are corrosive to metals.

Concept : Al will react with aqueous NaOH to give Sodium Aluminate with rapid evolution of H2 gas.In aqueous reaction conditions NaAlO2 will be accompanied by 2H2O i.e. “NaAlO2.2H2O”.

This actually exists as Al[OH4]- ions i.e. Sodium tetrahydroxoaluminate(III) ions. This reaction is highly exothermic and hence the solution heats up.The bubbles appears due to the evolution of Hydrogen gas

Materials required: beaker, glasses, sodium hydroxide pallets ( base), aluminium foil (metal),

Procedure:
1. Weigh 2gms of sodium hydroxide pallets
2. Add the sodium hydroxide pallets to 10mg of water.
3. Stir until all the pallets gets dissolved in the water.
4. Crumble a  small piece of aluminium foil.
5. Place it gently in the sodium hydroxide solution
6. observe

Observation:
The solution starts to boil with bubbles around the aluminium foil followed by this the aluminium foil starts disappearing leaving a while powdery substance floating in the solution.


Reaction :

2 Al +2 NaOH +6 H2O ----->  2 Na[Al(OH)4]+ 3H2

Application:

A drain cleaner is typically a chemical- based ased consumer product  which contains base that unblocks sewer pipes or clogged wastewater drains by reacting with the metal waste. 

when Drano is poured down a clogged drain; the hydrogen gas produced forces gunk out of the drain.