Unit 11.1: Water

• Chemical Tests for Water
  • Cobalt (II) chloride: paper turns from blue to pink
  • Anhydrous copper (II) sulfate: powder turns from white to blue
  • Both colour changes are reversible by heating

• Physical Tests for Water
  • Boils at 100°C
  • Freezes at 0°C

• Treatment of water supply 

1. Water is pumped through a screen to trap large particles (twigs, rocks, etc)

2. A coagulant is added to make small suspended…