1. Hydrogen production
   1. metal + acid ---> hydrogen + a salt
      1. vigour
         1. reactivity of metal
            1. magnesium (most reactive in this list)
            2. aluminim (2)
            3. Zinc (3)
            4. iron (4)
      2. salts
         1. named after acid
            1. hydrochloric
            2. chlorides
            3. sulphuric
            4. sulphates
   2. lab preparation
2. Combustion
   1. 2H2 (g) + O2 (g) --> 2H2O (l)
   2. + oxygen
      1. = water
   3. jet of burning hydrogen
      1. cold surface
         1. hydrogen oxide
         2. condenses
3. Test for water
   1. anhydrous copper sulphate
      1. white powder
      2. + water
         1. turns blue
      3. CuSO4 (s) + 5H2O ---> CuSO4.5H2O (s)
         1. heat copper (III) sulphate
            1. Blue to white
   2. pure water
      1. boil at 100C only
      2. + impurities
         1. boil at other temperatures
         2. + calcium chloride
            1. boiling 102C
4. Chlorine
   1. hydrogen + halogen
      1. hydrogen halide
   2. explosion
      1. heat
      2. sunlight
      3. ultraviolet light
   3. H2 (g) + Cl2 (g) ---> 2HCl (g)