The Membrane Cell
The membrane is made from a polymer which only allows positive ions to pass through it. That means that the only the sodium ions from the sodium chloride solution can pass through the membrane - and not the chloride ions. The advantage of this is that the sodium hydroxide solution being formed in the right-hand compartment never gets contaminated with any sodium chloride solution. The sodium chloride solution being used has to be pure. If it contained any other metal ions, these would also pass through the membrane and so contaminate the sodium hydroxide solution.
Production of the chlorine
Chlorine is produced at the titanium anode according to the equation:
2Cl-(aq) - 2e- --> Cl2 (g)
It is contaminated with some oxygen because of the reaction:
4OH-(aq) - 4e- --> 2H2O (l) + O2 (g)
The chlorine is purified by liquifying it under pressure. The oxygen stays as a gas when it is compressed at ordinary temperatures.
Production of the hydrogen
The hydrogen is produced at the nickel cathode:
2H+(aq) + 2e- --> H2(g)
Production of the sodium hydroxide
An approximately 30 per cent solution of sodium hydroxide solution is also produced at the cathode (see above - in the background chemistry section - for the explanation of what happens at the cathode).
Products listed on our website are either in stock or can be resynthesized within a reasonable time frame. N-octyl-4-metylpyridinium chloride
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