1. Option C12

2.  The chlor-alkali industry refers to the production of chlorine, sodium hydroxide and sodium carbonate.  Cl2 and NaOH are made from the electrolysis of brine solution (salt water).  The commercial methods used include mercury, and diaphragm and membrane cells.

3. Mercury Cell Process  Brine is passed into a cell with positive graphite electrodes.  At these anodes, oxidation of chloride ions takes place over hydroxide ions because of the higher concentration of chloride ions.  A moving layer of mercury acts as the negative electrode (cathode). Mercury is used because instead of hydrogen being reduced, sodium reacts with mercury forming an amalgam. (Na/Hg) Na + (aq) + e - + Hg(l) → Na/Hg(l) The amalgam then travels……

5.  The amalgam travels to a chamber containing water. Here, NaOH and H 2 are produced.  2Na/Hg + H 2 O → 2NaOH + 2Hg + H 2  The mercury is then recycled to be used again

6.  The negative and positive electrodes are separated by a diaphragm.  Diaphragms use asbestos (can cause damage to lungs). Membrane cells use ion-selective membrane technology (allows sodium ions to pass through).  Diaphragm allows sodium chloride to pass through, but prevents hydroxide ions from reaching the anode.  Positive anode is made from titanium. Negative cathode is made from steel.

8.  What is the half reaction at the anode?  2Cl - → Cl 2 + 2e -  What is the reaction happening at the cathode?  2H 2 O + 2e - → 2OH - + H 2  The hydroxide then combines with sodium to produce sodium hydroxide.  Bleach can be produced in a cold environment by reacting chlorine with hydroxide ions: Cl 2 (aq) + 2OH - (aq) → Cl - (aq) + ClO - + H 2 O(l)

9.  Chlorine: Solvents, manufacturing PVC, Bleaching paper products, Disinfecting drinking and swimming pool water, production of inorganic chemicals.  Sodium hydroxide: Manufacture of organic and inorganic chemicals (substitution reactions), Paper (converting wood to pulp), Aluminum industry, making soap.  Hydrogen: Hydrogenation, producing HCl, future use in fuel cells?

10.  Mercury: Supposed to be recycled in the process, but some inevitably escapes into the environment. This mercury reacts with many organic molecules, and intake of these organo-mercury molecules can cause sickness and mercury poisoning. Mercury poisoning can cause damage to the brain and CNS, and cause blindness, kidney failure, diarrhea, and several other problems

11.  Asbestos: Can cause respiratory tract cancer and asbestosis (respiratory disease caused by inhaling asbestos).  Chlorine: Used to make chlorine solvents and CFCs. CFCs form radicals which can deteriorate the ozone layer.