[muffins]

Hey all. I have a general question about redox reactions (just for my own understanding). Is it possible that in one reaction there will be more than one oxidizing or reducing agent? if anyone can, i'd like to see an example of that.

The next is an assignment question that I'm not sure much about. I need to balance the half reactions based on this reaction:
As₂S_3(aq)+NO₃^-_(aq)  H₃AsO_4(aq)+S_(s)+NO_(g)

So I figured that arsenic in As₂S_3(aq) has oxidation number 3+. nitrogen in NO₃^-_(aq) is 5+. then arsenic in H₃AsO_4(aq) is 5+, and nitrogen in NO_(g) is 2+. The question is about S_(s), what is the oxidation number of this? I did a bit of searching and couldn't find much info about sulfur existing in this form. Is it 0 because it's in a solid state? which brings me to ask, do all solids have oxidation number 0?

Thanks alot

[Borek]

Is it possible that in one reaction there will be more than one oxidizing or reducing agent?

That would yield two separate reactions IMHO.

The question is about S_(s), what is the oxidation number of this?

Oxidation number of a free element is always 0.

Note: it should be S(s) (state symbol not subscripted).

[muffins]

Thanks for your quick response Borek!
How do I address this reaction then? It seems like there are 2 reduction agents?

[Borek]

But their ratio is constant, so they work as one.

This is not a trivial one, but your fist half reaction can be a complete oxidation of As₂S₃.

[muffins]

Thank you very much