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elements of the sea (equilibrium (Kc tells position of equilibrium (Kc >…

- - - - chlorine= pale yellow
      - bromine= yellow/ orange
      - iodine= brown
    - - chlorine= pale yellow
      - bromine= orange/ red
      - iodine= purple
- - - - AgCl= precip dissolves in dilute ammonia solution to give colourless solution
      - AgBr= precip remains unchanged if dilute ammonia solution is added but will dissolve in concentrated ammonia to give colourless solution
      - AgI= precip doesn't dissolve
- - - - 1) use wires and clips to connect each electrode to the power supply. The electrode connected to the positive pole will be the anode and the electrode connected to the negative pole will be the cathode
      - 2) usually inert electrodes are needed (platinum/ carbon electrodes) so they don't react and interfere with the electrolysis
      - 3) place electrodes in a beaker containing the electrolyte making sure the electrodes aren't touching
      - 4) turn power supply on
      - 5) depending on electrolyte used, the products will form as metals (thin layer on the surface of the cathode - plating) or as gases (bubbles at cathode or anode)
  - - - if the metal is less reactive that hydrogen e.g. silver/ copper the metal WILL BE FORMED
      - if the metal is more reactive than hydrogen e.g. group1/2 and aluminium hydrogen gas will be formed (from hydrogen ions in water)
    - - if the solution doesn't contain a halide, oxygen WILL BE FORMED (4OH- ---> O2 + 2H2O + 4e-
      - if the solution is concentrated and contains a halide then the halogen will be formed
      - if the solution contains a halide but is dilute, oxygen will be formed
- - - - 1) at the cathode 2 hydrogen ions accept 2 electrons to become one hydrogen molecule - 2H+ + 2e- ---> H2
      - 2) at the anode two chloride ions lose their electrons and become one chlorine molecule - 2Cl- --> Cl2 + 2e-
      - 3) the sodium ions stay in solution because they are more reactive than hydrogen
      - 4) sodium ions and hydroxide ions (from water) are left behind while hydrogen and chlorine are removed, so sodium hydroxide is left in the solution
    - - in dilute solutions the Cl- ions aren't discharged - they hang on to their electrons. The OH- ions lose electrons instead and the products at the anode are oxygen and water (4OH- ---> 4e- + 2H2O + O2
  - - - brine contains some bromide ions
      - chlorine is more reactive than bromine, so when u bubble chlorine gas through brine, the chlorine will displace the bromine
      - 2Br- + Cl2 ---> Br2 + 2Cl-
      - the bromine is condensed into a liquid and purified
    - - brine contains iodide ions
      - chlorine is more reactive than iodine, so bubbling chlorine gas through brine will displace iodine
      - 2I- + Cl2 ---> I2 + 2Cl-
      - the iodine is purified and condensed into a grey solid