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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: o1ocups on April 08, 2009, 04:51:13 AM

Title: Why do some redox reactions contain two reduction reactions?
Post by: o1ocups on April 08, 2009, 04:51:13 AM

I don't understand why that happens. Wouldn't that make the reaction not a redox reaction?

For example: Na2SO4 (aq)

I have another question about this one: why does Na+(aq) + e- --> Na(s) occur in the cathode instead of the water reduction reaction? The Na+(aq) half reaction potential is -2.71 which is a lot lower than that of water. I thought the most positive reaction is the reaction that will occur.

Title: Re: Why do some redox reactions contain two reduction reactions?
Post by: o1ocups on April 08, 2009, 05:37:10 AM

Sorry, ignore my additional question about Na2SO4(aq). It was electrolysis.

Title: Re: Why do some redox reactions contain two reduction reactions?
Post by: AWK on April 08, 2009, 09:02:17 AM

Doing electrolysis of Na2SO4 you do in fact electrolysis of water.

Title: Re: Why do some redox reactions contain two reduction reactions?
Post by: o1ocups on April 08, 2009, 10:23:11 AM

Quote from: AWK on April 08, 2009, 09:02:17 AM

Doing electrolysis of Na2SO4 you do in fact electrolysis of water.

Yeah I know, but if you don't look at the water you do have two reduction reactions...

And I vaguely remember doing one other problem with two reduction reactions.

I guess my question should be: is it possible for a redox reaction to contain two reduction reactions?

Title: Re: Why do some redox reactions contain two reduction reactions?
Post by: sjb on April 08, 2009, 11:02:39 AM

It's always possible that you have more than one reaction going on in a system.

So A  :rarrow: A'; B  :rarrow: B' and C  :rarrow: C' . You may not need the presence of B to make the others go.

Title: Re: Why do some redox reactions contain two reduction reactions?
Post by: o1ocups on April 08, 2009, 03:28:01 PM

Quote from: sjb on April 08, 2009, 11:02:39 AM

It's always possible that you have more than one reaction going on in a system.

So A  :rarrow: A'; B  :rarrow: B' and C  :rarrow: C' . You may not need the presence of B to make the others go.

So you mean for some reactions, the only reason the species are written together is because they are contained within the same system? If they were to be released into a more open environment you would just write them as two separate equations?