group 2 compounds : reactions

• Reaction w/ oxygen

  • effervesence
  • becomes dull when it reacts with oxygen
• Reaction with dilute acids

  • forms salt + H2
• Properties of oxides

  • solubility increases down the group + resulting solution containing more -OH ions + more alkaline
  • Mg(OH)2 is only slightly soluble [low on conc, pH ~ 10]
  • Ba(OH)2 is much more soluble [greater OH conc, pH ~ 11]
• Reaction with water

  • effervesence
  • very reactive
• Uses of compounds

  • used to make bases + in neutralisations
• Uses of group 2 compounds

  • Neutralising acidic soils - Calcium hydroxide is used by farmers and garderners as 'lime' - it is used to reduce the acidity levels of soil
  • indigestion remedies - magnesium hydroxide in the milk of magnesia neutralises the excess acid producing a salt and water
  • building and construction uses - calcium carbonate - it is present in both limestone and marble and used in the building trade and in the manufacture of glass and steel [rainwater has an acidic pH so leads to gradual erosion of objects made using limestone and marble}