I have a pot with some (bottled) water and added (sea) salt. It has a pencil (graphite) and tin foil (aluminum). The pencil is connected to the positive outlet of a solar panel and the tinfoil is connected to the negative outlet of the solar panel (effectively 'charging' the electrolytic cell).

To ensure I don't come to harm, I would like to know:

A) What chemical(s) gas(es) are produced at the pencil? B) What chemical(s) gas(es) are produced at the tin foil? C) What will the chemical composition of the water generally be (assuming I've been charging it a while)? (Acidic, toxic, etc?).


Voltage determines the kind of reactions, amperage determines the amounts. The positive graphite electrode is the oxidizing anode. It will evolve oxygen and chlorine and be eroded to carbon dioxide, carbon monoxide, and chloro-organics. The negative aluminum electrode is the reducing cathode. It will reduce Na+ to elemental sodium that immediately reacts with water to make lye and hydrogen. The lye will erode the aluminum into more hydrogen and aluminum hydroxide gel, plus some black slime for about 1% alloy-reinforcing precipitated intermetallics in the aluminum foil (usually 8111 alloy). Lye plus chlorine gives hypochlorite bleach that will erode both electrodes, and do a little disproportionation into chloride plus chlorite, then that perhaps into chloride and chlorate.

Sodium carbonate (washing soda) is a more benign electrolyte, but it is an alkali hazard to eyes and skin. A glass is a more inert container. Do not short the electrodes, do it outdoors and stay upwind. Avoid electrolyte or product contact with your eyes and skin.

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  • $\begingroup$ Do you know how I would be able to easily test for the presence of lye (assuming I have no scientific equipment to hand)? $\endgroup$ – user4838 Mar 14 '14 at 17:54

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