Question

University of Connecticut Stamford Campus CHEM 1128 Spring 2017 Prof M. Ruiz-Martinez Home Work Set 8 due Tuesday April 18th before LECTURE starts. Problem #1 Balance the following redox reaction in acid Cra. a. H202 Cr20,2- Pb2+ 103 b. Pbo2

Problem 1 a-b

Answer 1

A oxidation half rxn H_2O_2 rightarrow O_2 balance �H�. For this add H^+ on �H� deficient side H_2O_2 rightarrow O_2 + 2H^+ balance e^- H_2O_2 rightarrow O_2 + 2H^+ + 2e reduction half rxn Cr_2O^-2 rightarrow Cr^+3 Cr_2O_3^-2 rightarrow 2 Cr^+3 balance �O� to balance �O� add H_2O on �O� deficient side Cr_2O_3^-2 rightarrow 2Cr^+3 + 7H_2O balance �H�. For this add H^-1 on deficient side Cr_2O_3^-2 + 14H^+ rightarrow 2Cr^+3 + &H_2O To cancel in both half room multiply oxidation half rxn by �3� b PbO_2 + I_2 rightarrow Pb^+2 + ID_3 overall: I_2 + 5PbO_2 + 8 H^+ rightarrow 5Pb^+2 + 2IO_3^- + 4 H_2O