Alloys, Hardness of Water & Important Chemical Compounds


Stainless steel Fe + Cr + Ni
Brass Cu (80 %) + Zn (20 %)   (Golden in Color)
Bronze Cu (90 %) + Sn (10 %)
Solder Pb (50 %) + Sn (50 %)
Steel Fe + C
Magnalium Al + Mg
Amalgam Hg + Ag + Sn + Zn  (used by dentists to fill teeth)
Duralium Al + Mg + Cu + Mn (making aircrafts, satellites & kitchenware)


Hardness of Water

Soft  Water
  • Produces leather with soap readily
Hard Water
  • Does not produce leather with soap readily
  • Due to the presence of bicarbonates, sulphates & chlorides of “Calcium & Magnesium”


Hardness of Water

Temporary Hardness Due to the presence of bicarbonates which can be removed easily by boiling & filtering
Permanent Hardness Due to the presence of sulphates & chlorides which cannot be removed by simply boiling water
Heavy Water Deuterium oxide (D2O) – Used as a moderator


Important Chemical Compounds

Cao (Quick Lime) 
  • Used for white wash of houses after diluting with water i.e. Ca (OH)2 or slacked lime
  • Also used in glass & cement manufacturing
  • Used in purification of sugar
Washing Soda (Na2CO3.10H2O) 
  • Used as detergent (Have cleaning properties)
  • Na2CO3 anhydrous is known as Fly Ash
  • Removes permanent hardness of water
  • Used to make Borax
Bleaching Powder (CaOCl2) 
  • Also known as chlorides of lime
  • Bleaching agent in CaOCl2 is chlorine (makes colored substance colorless)
  • Used in disinfecting water supply, bleaching cotton & in paper industry
Baking Soda (NaHCO3) 
  • Used for faster cooking of food & baking cakes, breads etc.
  • Used as Fire extinguishers (H2SO4 + NaHCO3 à CO2, which cuts oxygen supply)
  • Also used as antacid
Plaster of Paris (CaSO4.1/2H2O) 
  • Made by heating gypsum (CaSO4.2H2O)
  • Used in Plasters, fire proofing, wall smoothening, Making chalks &  Statues
  • Na & K salt of long chain of fatty acids (carboxylic acid)
  • Na salts – Hard soaps,    K Salts – Soft soaps (Shaving foam & shampoo)
  • Basic in nature
  • On adding common salt, solubility of soap decreases in water (Salting out)
  • Na salt of long chain of benzene sulphonic acid or alkyl hydrogen sulphate
  • Used for washing even with hard water


Important Chemical Compounds – Colours

White Vitriol Zinc Sulphate
Blue Vitriol Copper sulphate (Aq)
Green Vitriol Ferrous Sulphate
Wolfram Tungeston
Super Halogen Fluorine
Plastic Sulphur Allotrope of sulphur (super cooled liquid)
Chlorine – Yellowish Green Graphite – Black
Sulphur – Yellow Bromine – Reddish Brown
Phosphorus Red, White & Black (White – Most Reactive)
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