Oxides, acids and bases

• oxides --> compounds containing oxygen
• metallic 


  -basic oxides --> all other metals

  -amphoteric oxides --> aluminium, zinc oxide and lead oxide
• non-metallic


  -acidic oxides --> more than 1 oxygen (SO2, NO, NO2)

  -neutral oxides --> one oxygen (H20, C0)
• basic oxide + water --> alkali
• acidic oxide + water --> acid
• Basic oxide

  basic oxide + acid --> salt + water
• alkalis are strong bases that react with acids to form salts and water
• Acidic oxide

  acidic oxide + base --> salt + water
• basic oxides --> reacts with acid to form salt + water
• amphoteric oxides --> react with both acids and alkali to form salt + water
• acidic oxides --> react with alkali/base to form salt + water
• neutral oxides --> do not react with both acid and alkali
• 3 reactions of acids

  1)Acid + Base/Alkali --> salt +water

  2)Acid + Metal --> salt + hydrogen gas

  3)Acid + Metal carbonate --> salt + carbon dioxide + water
• Alkali 


  -produce hydroxide ions in aqueous solution

  -a soluble base which dissolves in water to produce OH- ions
• Acids


  -a substance that produces hydrogen ions, H2, when dissolved in water
• Base(alkali)


  -any metal oxide or hydroxide that reacts with an acid to produce salt + water only
• Acids physical properties 


  -sour taste

  -corrosive(only for strong acids)

  -turns damp blue litmus paper red

  -pH <7

  -conducts electricity in aqueous solutions
• Alkali physical properties


  -bitter

  -soapy and slippery

  -corrosive (only for strong alkalis)

  -turns damp red litmus paper blue

  -pH >7

  -conducts electricity in aqueous solutions
• Acids chemical properties


  -acid + metal --> salt + hydrogen gas

  -acid + metal carbonate --> salt + carbon dioxide gas + water

  
  

  neutralisation :

  -acid + metal oxide --> salt + water

  -acid + metal hydroxide --> salt + water
• Alkali/Bases chemical properties


  -alkali + ammonium salt --> salt + ammonium gas + water

  neutralisation :

  -alkali + acid --> salt + water
• Acids - controlling pH of soil (neutralisation)

  -due to too much fertilisers or acid rain

  -use calcium hydroxide (slaked lime) or calcium oxide (quicklime)