4. Acids and Redox

• Acids

  Release H+ ions when in aqueous solution
• Strong acids

  Strong acids completely dissociate in solution.
• Oxidation is a loss of electrons.
• Reduction is a gain of electrons.
• An oxidising agent accepts electrons and get reduced.
• A reducing agent donates electrons and gets oxidised.
• The oxidation number for an atom will increase by 1 for each electron lost.
• The oxidation number will decrease by 1 for each electron gained.
• When metals form compounds, they generally donate electrons to form positive ions, meaning they usually have positive oxidation numbers.
• When non-metals form compounds, they generally gain electrons, meaning they usually have negative oxidation numbers.
• Hydrochloric acid


  HCl
• Sulphuric acid


  H2SO4
• Nitric acids


  HNO3
• Ethanoic acid


  CH3COOH
• Sodium hydroxide


  NaOH
• Potassium hydroxide


  KOH
• Ammonia


  NH3
• Alkalis release OH- ions in aqueous solution.
• Acid + base


  Salt + water
• Alkali + acid


  Salt + water
• Metal + acid

  Salt + hydrogen
• Metal carbonate + acid

  Salt + water + carbon dioxide