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MgCl + HCL(aq) + electrolysis = ???????

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my question is that in this scenario what would the result be? i heard that MgCl under electrolysis will produce mg(s) + cl(g) which is what i am after. i am hoping that mg(s) would then react with the water to produce hydrogen(g) and Mg(oh)2 which would react with the HCl to form MgCl + 2(H20)



does this make sense or am i missing something?

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You are forgetting that the electrolysis will brake up HCl into hydrogen and Chlorine gas, and speaking from a generalized perspective, pure chlorine gas, is not something you want to deal with in large quantities, unless you observe necessary safety conduct. The magnesium, however is more likely to react with the HCl directly, rather than the H2O, leading to the formation of magnesium chloride. However, as the HCl decomposes, you'll get hydrogen as well as oxygen. It is my understanding that you are doing this, in an aqueous, HCl solution, to forgo the high temperatures involved in using molten chloride salts, however the method is rather inethical, as you shall obtain hydrogen as well as chlorine gas. You'ld also have to be careful in choosing your anode and cathode, as these can sometime initiate other reactions. To conclude such a method would not be practical. Your end product, which you'ld expect to be chlorine, would be intermixed with hydrogen, and as such, would result in impurities, due to the formation of HCl, and any present hydrogen.


2HCl > Cl2 + H2

Mg(Cl)2 > Mg2+ + Cl2

Mg2+ + 2HCl > Mg(Cl)2 + H2

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Time and time again, people post here (in these forums) thinking that electrolysis will magically break up any salt into its component parts in aqueous solution. It wont. Especially if your salt contains very reactive metals. Particularly metals which would normally react with water.

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  • 2 weeks later...

In regards to your question regarding magnesium oxide, yes it will react with water, in a similar fashion to calcium oxide, however, it is not something that you can attain by electrolysis. I recommend attaining oxide, through the decomposition of magnesium hydroxide, which can be done at a relatively low heat. A simple method to attain magnesium hydroxide is to add epsom salt (MgSO4) to an ammonia solution. You'll quickly get a milky white precipitate which can be easily filered out. (magnesium hydroxide) In regards to any compounds you make, I recommend use of MSDS's (material safety data sheets). Just do a google search, they're incredibly useful. Cheers!


MgSO4 + 2NH4OH > Mg(OH)2 + (NH4)2SO4


Mg(OH)2 > MgO + H2O


(The last reaction can then be performed in reverse, by dropping the magnesia into water)


MgO + H2O > Mg(OH)2


The best part is that, as the reaction with water, gives you hydroxide, you can simply filter the magnesium hydroxide from the solution, and perform the reaction again, decomposing, and then combining with water. (Though it does begin to get old over time)

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