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Ch.20 - Electrochemistry

Chapter 20, Problem 25a

Complete and balance the following equations, and identify the oxidizing and reducing agents: (a) Cr2O72-1aq2 + I-1aq2 ¡ Cr3+1aq2 + IO3-1aq2 (acidic solution)

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Hi everyone here we have a question asking us to balance the following redox reaction under acidic conditions and identify the oxidizing and reducing agents. We have chlor orrick acid plus hydrazine forms gold plus nitrogen plus hydrochloric acid. So our first step is to separate the whole reaction into half reactions. So we're going to have chlor oric acid forms gold plus hydrochloric acid and we're going to have hydrazine forms nitrogen. Next we're going to balance the non hydrogen and non oxygen elements. So we need to balance our chlorine on our first reaction. So we'll have chlor oric acid forms gold Plus four hydrochloric acid and that's balancing our chlorine. And in the next one our nitrogen is already balanced. So it's going to stay the same Now we need to balance oxygen by adding water to the sides that need it. So our first one is good and our second one is good. So we don't need to do anything there. And next we're going to balance our hydrogen by adding hydrogen to the sides that need it. So we'll have chlor orrick acid plus three hydrogen forms gold Plus four hydrochloric acid. And for our next reaction we'll have hydrazine forms nitrogen plus four hydrogen and now we need to balance the charge is we're going to add electrons to the more positive sides. So we're going to have cooler Orrick acid plus three hydrogen plus three electrons forms gold Plus four hydrochloric acid. And for our next one we're going to have hydrazine forms nitrogen plus four hydrogen plus four electrons. And now we need to balance the electrons on the two half reactions. So we're going to multiply this one by four. We're going to multiply this one x 3. So we are going to end up with four core orrick acid, plus 12 hydrogen plus 12 electrons, forms four gold plus 16 hydrochloric acid. And we're going to have three. Hi Justine forms three nitrogen plus 12 hydrogen plus 12 electrons. And now we need to add the two reactions. So our 12 hydrogen and our total electrons are going to cancel out And that's going to give us a total of four chlor oric assets. Plus three hydrazine forms four gold Plus 16 hydrochloric acids plus three nitrogen and losing electrons is oxidation. So our reducing agent is hydrazine gaining electrons, is reduction and are oxidizing agents. Are oxidizing agent is chlor orrick acid and those are our final answers. Thank you for watching. Bye.