s he blood aleoho ) level ean be determined by titratin a sample o d lasma wit i
ID: 545140 • Letter: S
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s he blood aleoho ) level ean be determined by titratin a sample o d lasma wit ion (Cr202 is orange in solution, and the Cr ion is green. The balanced equation is an die potassium di h umate solution resulting in te production o a and carbon d 0 de T e reaction can be monitored because the dichlo nate This reaction is an oxidation-reduction reactioa. a What species is reduced, and what species is oxidized? Species reduced: Cr Species oxidized: C2H,OH Drag and drop your selection from the following list to complete the answer: CO2 H2O Gr3- Correct For lhe reaction, we can assign the following oxidation states: Cr,072-: 2(a) + 7(-2)--2, z 6 GHsORI (GHO): 2(y) + 6(+1) + (-2) = o, v =-2 The chromium atomns go from the oxidation state ofnCo, to 13 in OP3H. Fach chromium atom gains three electrons, Cr0+ is the species rexduced. The carbon atoms go fro the oxidation state of-2 in C2OH to+4 in CO2. Each carbon atom loses six electrons: C2HO is the species oxidized b How many electrons are transferred in the balanced equation above? clectronsExplanation / Answer
In the reaction given, the species oxidised is ethanol and that reduced is dichromate. In that, chromium, the actual element donating the electrons, goes from an oxidation state of +6 dichromate to a +3 state. In dichromate, each oxygen takes -2. giving a total of -14, which with the overall charge of -2 gives a total of -12 to be balanced by 2 Cr atoms, giving it +6.
In ethanol, each carbon contains a total charge of -2 but in carbon dioxide, the carbon has a charge of +4. Hence, each carbon has to donate a total of 6 electrons thereby a total of 12 electrons. In the balanced equation, it can be seen that 1 equivalent of ethanol is oxidized by 2 equivalents of dichromate, giving 4 Cr atoms going from +6 to +3 state, accepting 3 electrons each arriving at a total of 12 electrons thus balancing the redox reaction.
Now, it can be observed that apart from carbon and chromium, no other element has a change in oxidation state. Therefore, it can be inferred that a total of 12 electrons have been transferred from ethanol's carbons to dichromate's chromium atoms in the balanced equation given.
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