1.
Write a detailed description of the alum crystals
Write a detailed description of the alum crystals
Solution
The term alum can refer to different chemical compounds, depending on the cation involved.
Alum is an hydrated sulfate of alluminium and another monovalent cation. the cation is
potassium, the formula is: KAl(SO 4 ) 2 *12H 2 O
Alums are widely double sulphate salts with a general formula AM(S04)2. 12H2O. Where A:
Monovalent cation such as potassium or ammonium. The increased size as well as the lack of
repelling charges cause the alum particles to settle down at the bottom or rise up and float in the
water.
After the particles are neutralized, they clump together because of the London Dispersion Force
which are part of the Van der Waals forces. Basically, weak intermolecular force arising from
quantum-induced instantaneous polarization multipoles in molecules causes even nonpolar
particles to attract each other due to the correlated movements of the electrons in interacting
molecules. Then they settles down.