C2h

C2h

1. Solution In Water

   • Water pumped underground to the salt deposit
   • Salt dissolves forming a solution of brine. This is then pumped above ground and to a purification plant.
   • This is safer than sending miners underground but causes subsidence, which can damage buildings as the ground is unstable.
     • Subsidence happens as there is not enough salt left in the ground, so the weight of the ground above causes it to sink downwards, which causes damage to buildings and roads.
   • Water is evaporated from the brine under different pressures in the plant, to make the process more efficient. The salt then crystalises and is separated from any remaining brine by using a centrifuge or filtering.

2. Rock salt mining

   • Big equipment and manual workers are used to extract rock salt.
   • This method can be dangerous for the workers and leaves impurities such as reddish clay.
   • This salt is used to grit roads as it doesn't have to be pure.

3. Electrolysis of brine

   • Products
     • Chlorine
       • Disinfectant and purifier, used to make hydrochloric acid and plastics.
     • Sodium hydroxide
       • Manufacture of paper, for processed food products and removing pollutants from water.
     • Hydrogen
       • Use to make hydrochloric acid and as a potential pollution free fuel.
   • Using electric current to bring a chemical change and make new chemicals.
   • Electrolysis of brine looks to make chlorine out of salt.
     • Hydrogen and sodium hydroxide are produced but must not tough each other as they react.
       • As they are reactive inert (un-reactive) solution must be used to separate them. This is the sodium hydroxide.
     • Hydrogen gas forms at the cathode as it is positive. Chlorine gas forms at the anode as it is negatively charged. Sodium hydroxide solution forms.
     • Anode (+)
       • Cl-: chlorine gas forms here
       • Oxidation happens as electrons are lost.
       • 2Cl- - 2e- goes to Cl 2
     • Cathode
       • Reduction happens as electrons are gained.
       • H+ gas is formed here
       • 2h= = 2e- goes to H2

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