The blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with an...


The blood alcohol {eq}(C_2H_5OH) {/eq} level can be determined by titrating a sample of blood plasma with an acidic potassium dichromate solution, resulting in the production of {eq}Cr^{3+}(aq) {/eq} and carbon dioxide. The reaction can be monitored because the dichromate ion {eq}(Cr_2O_7^{2-}) {/eq} is orange in the solution and the {eq}Cr^{3+} {/eq} ion is green. The balanced equation is as follows.

{eq}16H^+(aq) + 2Cr_2O_7^{2-}(aq) + C_2H_5OH(aq) \to 4Cr^{3+}(aq) + 2CO_2(g) + 11H_2O(l) {/eq}

This reaction is an oxidation-reduction reaction. What species is reduced, and what species is oxidized? How many electrons are transferred in the balanced equation?

Redox Reaction:

A redox reaction is made up of the simultaneous processes of oxidation and reduction. Certain reactant atoms are affected by these processes, causing a transfer of valence electrons and a change in oxidation states. You will often encounter redox reactions that appear highly complex, such that other atoms are also present, that are not oxidized or reduced. This makes it difficult to identify the oxidized and reduced atoms by inspection of the overall equation. In this case, the best approach is to systematically assign oxidation states to every reactant and product atom.

Answer and Explanation: 1

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The given balanced overall redox reaction equation for the titration is:

{eq}\rm 16H^+(aq) + 2Cr_2O_7^{2-}(aq) + C_2H_5OH(aq) \to 4Cr^{3+}(aq) +...

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Learn more about this topic:

Balancing Redox Reactions and Identifying Oxidizing and Reducing Agents


Chapter 10 / Lesson 13

Learn about oxidizing and reducing agents, how to find them, and how to identify them in redox reactions. Learn about the different types of redox reactions and how to identify a redox reaction.

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