Quiz 10-V1 key - Version 001 Quiz 10 fakhreddine(50415 This...

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Version 001 – Quiz 10 – fakhreddine – (50415)1Thisprint-outshouldhave10questions.Multiple-choice questions may continue onthe next column or page – find all choicesbefore answering.Msci04104100110.0pointsPermanganate oxidizes bromide ions in anaqueous acidic solution as shown below.MnO4+ H++ BrMn2++ H2O + Br2How many electrons are involved in the per-manganate half-reaction and on which side ofthe equation are these electrons to be added?Consider the following voltaic cell:Pt|Sn2+(0.50 M),Sn4+(0.050 M)||Ag+(0.0010 M)|Ag1.10 electrons on the reactant side2.5 electrons on the reactant sidecorrect3.10 electrons on the product side4.6 electrons on the product sideExplanation:The oxidation number of Mn changes from+7 to +2, so Mn is reduced.We set up thereduction half-reaction:MnO4Mn2+Mn atoms are balanced. In acidic solutionwe use H2O and H+to balance O and Hatoms, adding the H2O to the side needingoxygen:8 H++ MnO4Mn2++ 4 H2OWe balance the total charge in the half-reaction by adding electrons. In the preceed-ing reduction reaction there is a total chargeof +7 on the left and +2 on the right.Fiveelectrons are added to the left:5e+ 8 H++ MnO4Mn2++ 4 H2ONernst0100210.0pointsSn4++ 2e=Sn2+E0= 0.15VAg++ 1e=Ag(s)E0= 0.8V

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