Saturday, September 5, 2020


Bases are the substances which give hydroxyl ion(OH-) in aqueous solution. Almost all bases are oxide or hydroxide of metals. Most of bases form alkali on aqueous solution. That’s why all alkali are base but all bases are not alkali because all bases do not dissolve in water.

Classification of bases: Bases are classified as strong and weak base. The base which dissolve completely in water and gives sufficient amount of hydroxyl ion in aqueous solution are called strong bases. NaOH and KOH are example of strong bases. The bases which give little amount of hydroxyl ion on dissolving with water are weak base. for example Ca(OH)2 and NH4OH

Properties of bases

  • Bases have generally bitter taste and are slippery on touch
  • Solution of base turns red litmus to blue
  • Strong bases like NaOH and KOH dissolve with oil, fat and grease
  • Base react with acid to form salt and water
  • Solution of base(alkali) react with carbon dioxide to form carbonate

2NaOH + CO2 → Na2CO3 + H2O

  • Bases react with ammonium salts to form ammonia

NH4Cl + NaOH → NH3 + NaCl + H2O

Uses of bases

  • NaOH: making soap, paper production, purification of mineral oil
  • KOH: making shampoo & saving cream
  • Ca(OH)2: production of bleaching powder
  • CaO: cement production, removing hardness of hard water
  • Mg(OH)2: reducing acidity on stomach
  • NH4OH: making chemical fertilizer, plastic production etc


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