Chem100A_Exp6_Oxidation of Alcohol by DichromateIon_QuizKEY_20110504

Chem100A_Exp6_Oxidation of Alcohol by DichromateIon_QuizKEY_20110504

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Spring 2011 Student ID:_______________________________ Experiment 6: Oxidation of Alcohol by Dichromate Ion Quiz #5 (20 points)–May 04, 2011 1. (4 points) The  balanced reaction for the oxidation of ethyl alcohol (CH 3 CH 2 OH) with dichromate  is:   3 CH 3 CH 2 OH+ 2Cr 2 O 7  -2  + 16H +    3 CH 3 COOH +4Cr +3   + 11H 2 O a) Write out the general rate law for this oxidation reaction. Rate = k[CH 3 CH 2 OH] x [Cr 2 O 7 2- ] y [H + ] b) Why does H  +  appear in the rate law but not in the balanced reaction? It acts as a catalyst and is neither lost or gained so does not appear in the stoichiometry . 2. (4 points)  A sample has a transmittance of 10%, what is the absorbance?  Give the molar  absorptivity if the concentration of the sample is 0.1M and we are using a 1cm cuvette. 3. (4 points)  For the  initial  rate of formation of NOCl(g):   NO(g) + ½Cl 2 (g) <--> NOCl(g) [NO(g)] (mol dm -3 ) [Cl 2 (g)] (mol dm -3 ) Initial Rate (mol dm -3  s -1 ) 0.250 0.250 1.43 x 10 -6 0.250 0.500 2.86 x 10 -6 0.500 0.500 11.4 x10 -6
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Spring 2011 Student ID:_______________________________ FFigure  - Initial rate data a) Write the rate law. Doubling Cl in  lines 1 and 2 doubles the reaction rate. Doubling NO in lines 2 and 3 quadruples it. b) Give the value of the rate constant. 4.  (4 points): Balance the following redox reaction in acidic solution: Cr 2 O 7 2- (aq)  +  HNO 2 (aq)    Cr 3+ (aq)  +  NO 3 - (aq)   (acidic) Cr 2 O 7 2- (aq) + 3HNO 2 (aq)+5H + (aq)    2Cr 3+ (aq)+3NO 3 -  (aq) +  4H 2 O(l) Solution: Step #1:    Write the skeletons of the oxidation and reduction half-reactions. You will usually be given formulas for two reactants and two products. In such cases, one of the reactant 
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This note was uploaded on 11/26/2011 for the course CHEM 100A taught by Professor Dai during the Spring '06 term at UCSD.

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Chem100A_Exp6_Oxidation of Alcohol by DichromateIon_QuizKEY_20110504

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