PROCEDURE
1. Prepare 50ml of 4M KOH solution.
2. Add small pieces of aluminium foil (about 1 gm) in the conical
flask containing the KOH solution. Since during this step hydrogen
gas is evolved, this step must be done in a well-ventilated area.
3. After all of aluminium has reacted, filter the solution to remove
any insoluble impurities.
4. Allow the filtrate to cool. Now add slowly conc. H2SO4
until insoluble Al(OH)3 just forms in the solution
5. Gently heat the mixture until the Al(OH)3 ppt. dissolves.
Leave the solution overnight for the crystallization to continue.
6. Take out the crystals and wash them with 50/50 ethanol-water
mixture.
7. Determine the mass of the alum crystals.
OBSERVATIONS
Mass of aluminium metal = 1 gm
Mass of potash alum = 13 gm
Colour = White
Shape of crystals = Octahedral
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