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  • 1. Acids and Bases
  • 2. What are these? Lemon Coke Vinegar Acids
  • 3. What is an Acid?
    • An acid is a substance that produces hydrogen ions, H + in water.
    • An acid therefore can conduct electricity .
    • pH < 7
    • It has a sour taste.
    • It has a stinging feeling .
    • It is corrosive .
  • 4. What are these? Window Cleaner Floor Cleaner Baking Soda Bases
  • 5. What is an Alkali?
    • An alkali is a substance that produces hydroxide ions, OH - in water.
    • An alkali can conduct electricity.
    • pH > 7
    • It has a bitter taste.
    • It is caustic .
    • It is corrosive .
  • 6. Examples of Acids I n the preparation of fertilizers and explosives HNO 3 Nitric acid In fizzy drinks H 2 CO 3 Carbonic acid In oranges and lemons C 6 H 8 O 7 Citric acid In vinegar CH 3 COOH Acetic acid In car battery H 2 SO 4 Sulphuric acid In gastric juice in the stomach HCl Hydrochloric acid Where can it be found? Chemical formula Names of acids
  • 7. Acidic or not? Yes Nitric acid HNO 3 (aq) No water H 2 O (s) Yes Ethanoic acid/acetic acid CH 3 COOH(aq) Yes Sulphuric acid H 2 SO 4 (aq) Is it Acidic? Name of compound Chemical name
  • 8. Strength of an Acid
    • The strength of an acid depends on the extent of ionisation .
    • The acid is stronger when more molecules are ionised.
  • 9. Strong Acids : acid molecule Dissolved in water : acid ions _ + _ _ _ _ + + + + _ +
  • 10. Strong Acids
    • A strong acid is one in which all the acid molecules become ions in water.
    • Examples: Hydrochloric acid, HCl (aq)
    • Sulphuric acid, H 2 SO 4 (aq)
    • Nitric acid, HNO 3 (aq)
  • 11. Weak Acids : acid molecule : acid ions Dissolved in water _ + _ +
  • 12. Weak Acids
    • A weak acid is one in which only a few acid molecules become ions in water.
    • Examples: Acetic acid, CH 3 COOH (aq)
    • Citric acid, C 6 H 8 O 7 (aq)
    • Carbonic acid, H 2 CO 3 (aq)
  • 13. Reaction of Acids with Metals
    • General Equation:
    • Metal + Acid  Salt + Hydrogen gas
    • Observation:
    • The metal dissolves
    • and effervescence occurs.
    • The gas extinguishes a burning
    • splint with a ‘pop’ sound.
  • 14. Reaction of Acids with Metals
      • Mg(s) + 2HCl(aq) 
      • Ca (s) + H 2 SO 4 (aq) 
      • Zn (s) + H 2 SO 4 (aq)  ZnSO 4 (aq) + H 2 (g)
    MgC l 2 (aq) + H 2 (g) Magnesium chloride + hydrogen gas CaSO 4 (aq) + H 2 (g) Calcium sulphate + hydrogen gas Zinc + sulphuric acid Magnesium + H ydrochloric acid  Calcium + Sulphuric acid   Zinc + sulphate
      • H ydrogen
      • gas
  • 15. Reaction of Acids with Carbonates
    • General Equation:
    • Metal + Acid  Salt + Water + Carbon Carbonate dioxide gas
  • 16. Reaction of Acids with Carbonates
    • Observation:
    • The metal dissolve and effervescence occurs. The gas forms a white precipitate with limewater.
  • 17. Reaction of Acids with Carbonates MgC l 2 (aq) + H 2 O (l)+ CO 2 (g) Magnesium chloride + water + carbon dioxide CaCO 3 (s) + H 2 SO 4 (aq) Calcium + sulphuric Carbonate acid
      • MgC O 3 (s) + 2HCl(aq) 
    Magnesium + carbonate H ydrochloric acid 
      •  CaSO 4 (aq) + H 2 O ( l ) + CO 2 ( g )
    Calcium + sulphate
      • Water +
      • Carbon
      • dioxide
      • gas
  • 18. Reaction of Acids with Alkalis
    • General Equation:
    • Alkali + Acid  Salt + Water
  • 19. Reaction of Acids with Bases
    • Base: Metal oxides, Metal hydroxides
    • NaOH + HCl 
    • KOH + H 2 SO 4 
    Sodium hydroxide Hydrochloric acid Potassium hydroxide Sulphuric acid + + + +   NaC l (aq) + H 2 O (l) Sodium chloride water K 2 SO 4 (aq) + H 2 O (l) Potassium sulphate water
  • 20. Uses of Acids Acids Preserving food -acetic acid in vinegar M aking industrial products -nitric acid in fertilisers -sulphuric acid in detergents Rust removal from iron and steel -Sulphuric acid -Hydrochloric acid Car battery -Sulphuric acid
  • 21. Complete the Puzzle
    • Across
    • Acids react with _______ to give salt and water only.
    • 5. Only _______ solution of acids have acidic properties.
    • 6. In a strong acid, the acid molecules are _______ ionised.
    • 8. Ethanoic acid is an example of a _______ acid.
    • 9. Acids have a _______ taste.
    • Down
    • 2. _______ acid is an example of a strong acid which is found in car battery.
    • 3. _______ react with acids to give off a gas that forms a white precipitate with limewater.
    • 4. When dissolved in water, acid molecules can ionise to give _______ ions.
    • 7. Hydrogen gas is evolved when acids reac t with _______.
  • 22. Answer
    • Across
    • Acids react with bases to give salt and water only.
    • 5. Only aqueous solution of acids have acidic properties.
    • 6. In a strong acid, the acid molecules are completel y ionised.
    • 8. Ethanoic acid is an example of a weak acid.
    • 9. Acids have a sour taste.
  • 23. Answer Down 2. Sulphuric acid is an example of a strong acid which is found in car battery. 3. Carbonates react with acids to give off a gas that forms a white precipitate with limewater. 4. When dissolved in water, acid molecules can ionise to give hydrogen ions. 7. Hydrogen gas is evolved when acids reac t with metals .
  • 24. Summary
    • An acid is a substance that produces hydrogen ions in water.
    • Only an aqueous solution of acid has acidic properties.
    • HCl (aq)  H + (aq) + Cl - (aq)
    • The greater the extent of ionisation, the stronger the acid.
  • 25. Summary
    • An acid
    • - pH < 7
    • - turn blue litmus paper red.
    • - taste sour
    • - stinging feeling
    • - is corrosive (for strong acids)
    • - can conduct electricity.
  • 26. Summary
    • Reactions of acids with
    • 1. metals
    • Metal + Acid  Salt + Hydrogen gas
    • 2. carbonates
    • Metal + Acid  Salt + Water + Carbon Carbonate dioxide gas
    • 3. bases
    • Base + Acid  Salt + Water
  • 27. Summary
    • An alkali
    • - pH > 7
    • - turn red litmus paper blue
    • - taste bitter
    • - caustic
    • - is corrosive (for strong alkalis)
    • - can conduct electricity.
  • 28. pH Indicators
    • Methyl orange:
  • 29. pH Indicators
    • Universal Indicator
  • 30. pH Indicators
    • Phenolphthalein