Short Notes on Bases (Acid, Bases and Salts)

BASES:

A base can be defined as a substance capable of releasing one or more OH- ions in aqueous solution. They are bitter in taste and soapy in touch.

A base which completely ionizes in water and thus produces a large amount of hydroxide ions(OH- ions ) is called a  Strong Base / Strong Alkali. e.g. Sodium Hydroxide and Potassium Hydroxide.

A base which is partially ionized in water and thus produces a small amount of hydroxide ions is called a Weak Base / Weak Alkali. e.g.  Ammonium Hydroxide.

Water soluble bases (like Sodium hydroxide and Potassium hydroxide ) are know as Alkalies .

List of some alkalies and their uses:

Name Commercial Name Chemical Formula     Uses
Sodium Hydroxide Caustic Soda NaOH In manufacture of soap, paper, pulp, rayon, refining of petroleum etc.
Potassium hydroxide Caustic Potash KOH In alkaline storage batteries, manufacture of soap, absorbing CO2 gas etc.
Calcium Hydroxide Slaked lime Ca(OH)2 In manufacture of bleaching powder softening of hard water etc.
Magnesium Hydroxide Milk of Magnesia Mg(OH)2 As an antacid to remove acidity from stomach
Aluminum Hydroxide Al(OH)3 As foaming agent in fire extinguishers.
Ammonium Hydroxide  Liquor ammonia NH4OH In removing greases stains from cloths and in cleaning window pane.

Properties Of Bases :

The important properties of bases are:

  1. Bases have a bitter taste.
  2. Bases feels soapy in touch.
  3. Base turn red litmus blue. (Click here  to know more about indicators and color change)
  4. Bases conduct electricity in solution (They are electrolytes): When bases are dissolved in water, it splits    up in ions. Due to the presence of ions the base solution conduct electricity.
  5. Basis react with some metals to form hydrogen gas: Metals like Zinc, Tin and Aluminum react with strong alkalies like NaOH, Caustic Soda, KOH (Caustic Potash) to evolve hydrogen gas. (Click here for detailed experiment).                                                                                                                                                                                                                                                               Zn(s) + 2NaOH(aq) → Na2 + ZnO2(aq) + H2(g)
  6. Basis react with non metal oxides to form salt and water: Acids react with metal oxides, but bases react with oxides of non-metals to form salt and water.For e.g. 2NaOH(aq) + CO2(g) → Na2CO3(aq) + H2O

The Reaction of non metal oxides with bases to form salt and water shows that non metal oxides are acidic in nature.

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