6.1 PROPERTIES OF ACIDS AND ALKALIS

• Properties of Acid

  • pH value less than 7
  • Tastes sour
  • Corrosive
  • Turns blue litmus paper red
  • Reacts with metals to produce hydrogen gas
• Properties of Alkali

  • pH value more than 7
  • Tastes bitter
  • Corrosive
  • Turns red litmus blue
  • Does not react with metals
• Phenolphthalein

  Acid: Colourless

  Neutral: Colourless

  Alkali: Pink
• Universal indicator

  Acid: Red

  Neutral: Green

  Alkali: Blue
• Methyl orange

  Acid: Red

  Neutral: Yellow

  Alkali: Blue
• Blue litmus paper

  Acid: Red

  Neutral: Blue

  Alkali: Blue
• Red litmus paper

  Acid: Red

  Neutral: Red

  Alkali: Blue
• Acidic

  • vinegar
  • lemon juice
• Alkaline

  • soap
  • toothpaste
• Use of Acids and Alkalis in Daily Life

  • vinegar - cooking
  • detergent - washing clothes
  • agriculture
  • industry
  • medicine
• Acid

  • Tartaric acid
  • Carbonic acid - Fizzy frink
  • Sulphuric acid - Car battery
  • Vinegar - Pickle
• Alkalli

  • Potassium hydroxide - Soap
  • Ammonia - Fertiliser
  • Magnesium hydroxide - Antacid pills
  • Sodium hydroxide - Detergent