Chem33-1, C-hour Problem Set 6Due Date: Nov. 19, 2007 Student name: ___________________ Student SISD #: __________________ 1.The following elementary reaction is very useful in organic chemistry: −−+→+ClOHCHOHClCH33This reaction is first order in CH3Cl and first order in OH-. What is the rate law? ANSWER: Generally, nmBAkrate][⋅⋅=Since this reaction is first order in both CH3Cl and OH-, 1==nm. Therefore, ][3−⋅⋅=OHClCHkrate2.Balance the following oxidation-reduction reactions, which occur in basic solution, using the half-reaction method. Al(s) + MnO4-(aq) →MnO2(s) + Al(OH)4-(aq) ANSWER: Use the same method as with acidic solutions. After the final balanced equation, then convert H+to OH-as described in section 4.11 of the text. The extra step involves converting H+into H2O by adding equal moles of OH-to each side of the reaction. This converts the reaction to a basic solution while keeping it balanced. Al →Al(OH)4- MnO4-→MnO2 4H2O + Al →Al(OH)4-+ 4 H+3 e-+ 4 H++ MNO4-→MnO2+ 2 H2O 4H2O + Al →Al(OH)4-+ 4 H+ + 3 e- 4 H2O + Al →Al(OH)4-+ 4H++ 3 e-3 e-+ 4 H++ MNO4-→MnO2+ 2 H2O 2H2O(l) + Al(s) + MnO4-(aq) →Al(OH)4-(aq) + MnO2(s) Since H+doesn’t appear in the final balanced reaction, we are done.
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