AF

 Chapter 13:Acids and Bases

Properties of acids

  • Acid: any substance that releases hydrogen ions, H+, in aqueous solution
    • [ ] Aqueous solutions of acids are electrolytes,
  • Acids have a sour taste
    • [ ] Example: Lemons, vinegar, and sour candies all contain acids.
  • Acids change the color of certain acid-base indicates.
  • Acids react with active metals to yield hydrogen gas.
  • Acids react with bases to produce a salt compound and water.
  • Turn blue litmus red
  • Turn methyl orange red
  • Turns Phenolphthalein colourless
  • TiUniversal indicator Red /orange
  • Contains PH-level below 7

Organic acid

  • Organic Acid : found in natural products such as plants and animals.
    • [ ] They are sour to taste.
    • [ ] These acids are relatively harmless.( For example), they are not corrosive etc.
    • [ ] Example of some common organic acids: Ethanoic acid, citric acid, lactic acid.

Inorganic acid

  • Inorganic acids: are corrosive, they have a sour taste and turn blue litmus red.
    • [ ] Hydrochloric acid
    • [ ] Sulphuric acid
    • [ ] Nitric acid

Weak and strong acid

  • Strong acid which is completely ionized in an aqueous solution.

    • [ ] Eg: Hydrogen chloride (HCl), sulphuric acid, nitric acid.

  • Weak acid which partially ionises in an acquous solution.

  • [ ] Eg:carbonic, ethanoic , sulphurous, citric , carbonic.

Bases

  • Bases: form a class of chemical substances which include all metal oxides and hydroxides.
    • [ ] A soluble base is called an 'alkali' an in aqueous solution, it produces hydroxide ion (OH-)

Properties of Bases

  • Proton acceptors
    • [ ] as they contain hydroxide ions
  • PH greater than 7
  • Bitter taste
  • Bases effect indicators
  • Turn red litmus Blue
  • Phenolphthalein turns purple/pink
  • Universal indicator Blue
  • Methyl orange YELLOW
  • Slippery solutions
  • Bases neutralise acids
  • React with acids to form salt and water
  • Examples of bases: Sodium hydroxide, potassium hydroxide, acqeuous ammonia, calcium hydroxide, magnesium oxide, copper (II) oxide.

Reactions

  • Metal and acid➡️ salt and hydrogen

  • [ ] Eg: zinc + sulphuric acid➡️ zinc sulphate+ Hydrogen

  • Metal oxide + acid ➡️ salt and water

  • [ ] Eg: Copper(II) oxide + sulphuric acid➡️ copper sulphate+ water

  • Metal hydroxide + acid ➡️salt and water

  • [ ] Eg: Potassium hydroxide+ hydrochloric acid ➡️ potassium chloride + water

  • Metal carbonate + acid ➡️salt+water+ carbon dioxide

  • [ ] Eg: Zinc carbonate+ nitric acid ➡️ zinc nitrate +water+ carbon dioxide

Oxides

  • Basic oxides :solid metal oxides, some of which dissolve in water to form alkalis
  • Acidic oxides :non-metal oxides, which dissolve in water to form acids
  • Neutral oxides :non-metal oxides which are usually insoluble in water and have neither acidic nor basic properties
  • Amphoteric oxides : metal oxides which can react with both acids and alkalis to form salts and water.