<p>"H2O2 can act either as an oxidizing agent or a reducing agent depending on the acidity of the solution. Write half-reactions for H2O2 acting as an oxidizing agent and a reducing agent."</p>
<p>So far I've come up with this:
a. Oxidizing agent: 2Co(OH)2 (s) + H2O2 (aq) --> 2Co(OH)3 (s)
b. Reducing agent:
2Co(OH)3 (s) + H2O2 (aq) + 4H+ (aq) --> 2Co2+ (aq) + O2 (g) + 6 H2O (l)</p>
<p>But I'm not sure how to make those into half-reactions. Any help would be awesome.</p>
<p>I have never heard of half-reactions.</p>
<p>Do you mean net-ionic equation?</p>
<p>...Half reactions must include the electron transfer.</p>
<p>So..</p>
<p>Basically it's saying it's a disproportionation redox reaction</p>
<p>2e- + 2H+ + H2O2 --> H2O + H2O (reduction: oxidizing agent)</p>
<p>H2O2 --> O2 + 2H+ + 2e- (oxidation: reducing agent)</p>
<p>I believe.</p>
<p>EDIT:</p>
<p>I believe they also may have wanted this instead </p>
<p>2e- + H2O2 --> 2OH- (basic solution), it's basically the same thing as the first one except it cancels the waters and what not, except I believe the more correct form would still be </p>
<p>2e- + H2O+ H2O2 --> H2O + 2 OH-</p>
<p>So you don't include the thing that's being oxidized (the Co) at all?? It's just a generic thing?</p>
<p>And for this: 2e- + 2H+ + H2O2 --> H2O + H2O (reduction: oxidizing agent)</p>
<p>What are the H+ for? Just to balance out the e-?</p>
<p>Thanks for your help though :)</p>
<p>Also, can you tell me if this similar one is right?</p>
<p>"When NH3 is added to solid Hg2Cl2, some of the mercury ions are oxidized and some are reduced. A reaction where the same substance is both oxidized and reduced is called a disproportionation reaction. Write equatiosn for each of these half reactions."</p>
<p>a. Reduction: Hg2Cl2 (s) + 2e- + 2H+ (aq) --> 2Hg (l) + 2HCl (aq)
b. Oxidation: Hg2Cl2 (s) + 2NH4+ (aq) 2HgNH2Cl (s) + 4e- + 4H+ (aq)</p>
<p>The H+ means it's in acidic solution basically, and yes it is to balance out the charges. The Co I don't really think you need to include it.</p>
<p>It looks pretty right except for the fact that you might want to rewrite it as ions. Because it says some of the IONS are oxidized while this makes it appear more as if the solid itself is oxidized, although personally I do not think it matters that much.</p>
<p>I'm not sure about the oxidation one, but I believe for B you need to use ammonia and not switch it to ammonium because it becomes a complex ion anyways. I'm not that confident on that one. I believe if one is acidic you should rewrite the other as basic.</p>
<p>Oh... in a previous part of the assignment, the equation</p>
<p>Hg2Cl2 (s) + 2NH3 (aq) --> Hg (l) + HgNH2Cl(s) + NH4+ (aq) + Cl- (aq)</p>
<p>was given. But how do you know whether to put the NH3 and NH4+ in either reaction?</p>