01 Planet Earth

• Filtration is used to separate insoluble solids from a solution.
• Evaporation is used to obtain solute from solution.
• Crystallization is used to obtain more pure solute from a solution.
• Distillation is used to obtain pure water from sea water.
• Anti-bumping granules is used in distillation to ensure even heating.
• Procedure for flame test

  1. Cleaning: dip platinum or nichrome wire into concentrated hydrochloric acid and burn. Repeat until no special colour is observed.
  2. Dip wire into concentrated hydrochloric acid.
  3. Dip wire into the crushed sample of salt.
  4. Burn the wire in a non-luminous flame
• Water turns dry cobalt (II) chloride paper from blue to pink.
• Water turns anhydrous copper (II) sulphate from white to blue.
• Test for chloride ion:

  1. Dissolve the sample in water
  2. Add acidified silver nitrate solution

  Formation of white precipitate indicates the presence of chloride ion.
• In electrolysis of sea water, chlorine gas is formed in the positive electrode while hydrogen gas is formed in the negative electrode. Sodium hydroxide remains.
• Hydrogen is used in manufacture of ammonia and as rocket fuel.
• Hydrogen and chlorine are used in manufacture of hydrochloric acid.
• Chlorine is used to sterilize drinking water, to sterilize swimming pool water, and in manufcature of PVC and organic solvents.
• Chlorine and sodium hydroxide are used in manufacture of bleach.
• Sodium hydroxide is used in the manufacture of soaps and detergents.
• Calcium carbonate turns into calcium oxide and carbon dioxide when heated.
• Calcium oxide reacts with water to form calcium hydroxide.
• Calcium hydroxide is slightly soluble in water.
• Calcium hydroxide solution reacts with carbon dioxide to form calcium carbonate.
• Calcium carbonate reacts with dilute hydrochloric acid to form calcium chloride, water, and carbon dioxide.
• Calcium carbonate reacts with water and carbon dioxide to form calcium hydrogencarbonate.
• Test for carbonate ion:

  1. Add dilute hydrochloric acid to the sample.
  2. If colourless bubbles that turn limewater from colourless to milky evolve, carbonate ion is present.