Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: lordofdarkness on June 18, 2005, 10:30:52 PM
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What are the products of the electrolysis of saltwater using aluminium for anodes"?
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I'm not sure on this one but it wouldn't be to safe if the Cl and Na parted ways. You'd have chlorine gas and a volatile compound that'll want to react. Plus you'll get hydrogen in a rich oxygen enviroment (because of the O coming from the H20). Doesn't sound safe to me.
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at the cathode u'll obtain hydrogen (nothing to do with the atmosphere, just the water in the your solution)
2H+ +2 e- --> H2
and at the anode u'll obtain chlorine or oxygen, depending on the concentration of chloride ions because there are 2 possible reactions
4OH- --> 2H2O + O2 + 4e-
or
2Cl- --> Cl2 + 2e-
aluminium being oxidised is a small possibility, because its oxide layer prevents it from participating in the reaction.
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aluminium being oxidised is a small possibility, because its oxide layer prevents it from participating in the reaction.
In case of water hydolysis OH- will dissolve oxide layer as aluminum is amphoteric.
No exact idea about what will happen on the electrode surface if the chlorine evolves, but I doubt aluminum anode will survive long in such environement.
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The Aluminum won't last long at all. As the electrolysis takes place, you'll be forming a fairly strong sodium hydroxide solution which will eat away at the aluminum forming a lot of hydrogen gas. You'll also have the chlorine gas reacting directly with the aluminum where the oxide layer has been eroded away. Finally, the little bits of HCl that form as a result of the dissolution of chlorine gas will eat away at the aluminum as well.
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I'm doing this as well and I'm a little worried that Aluminum Chloride could be created through this, am I safe or should I not continue with using aluminum as my anode?
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For aqueous electrolysis, don't use aluminium electrodes. You'd only get an ugly mess. Take stainless steel or graphite. Saline batteries contain a graphite electrode which you can extract, if minding the other compounds in the battery.
Electrolysis of salt water: no, you are NOT safe. This is not a matter of electrodes. Salt water electrolysis releases chlorine and hypochlorite, and both are harmful. It's a matter of ventilation and of production rate. A simple base like NaOH would be better.
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