Acids

• Acids

  • an acid is a substance that produces hydrogen ions when dissolved in water
  • have a sour taste
  • conduct electricity due to presence of mobile ions produced when dissolved in water
  • turn blue litmus paper red
  • react with metals to form salts and hydrogen gas (MASH)
  • neutralisation : react with bases (e.g. metal oxides and metal hydroxides) to from salt and water (AAWS)
  • react with carbonates to form salts, water and carbon dioxide (ACSCW)
• Examples of Acids

  • hydrochloric acid HCl
  • nitric acid HNO3
  • Sulfuric acid H2SO4
  • Ethanoic acid CH3COOH
• Strong and Weak Acids

  • hydrochloric acid, nitric acid and sulfuric acid are strong acids
  • ethanoic acid is a weak acid CH3COOH -> CH3COO- + H+
  • strong acids ionise completely in aqueous solutions
  • strength of an acid refers to the extent of ionisation of the acid in an aqueous solution
  • strength remains the same even if concentration is changed
• Basicityof acids


  • refers to the number of hydrogen ions per acid molecule
  • e.g. HCl is monobasic and H2SO4 is dibasic