# Assignment 5 Answers - 10-2(9.649-nFE G 4-= = = ( 29 54 )...

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Quantitative Analysis Assignment #5 Due 11/17/04 Electrochemistry and Titrations The attached article describes a possible electrochemical reaction responsible for the corrosion of copper pipes. Of course, it isn’t as simple as a redox reaction as the ongoing research indicates. 1) Calculate , , and K for the reaction if Cl 2 ( aq ) is reduced to Cl - ( aq ) and a) Cu (s) is oxidized to Cu + ( aq ), and b) Cu( s ) is oxidized to Cu(OH) 2 ( s ). Is either reaction spontaneous? a) 396 . 1 2Cl 2e ) ( Cl 2 = + + - - E (aq) aq 518 . 0 2Cu 2e ) ( 2Cu = + - - + E (s) aq 878 . 0 2Cl Cu 2 ) ( Cl 2Cu 2 = + + - + E (aq) (aq) aq (s) kJ 169 )(0.878) 10 -2(9.649 -nFE G 4 - = × = = ( 29 29 ) 05916 . 0 /( ) 878 . 0 )( 2 ( 05916 . 0 / 10 81 . 4 10 10 × = = = nE K It is spontaneous b) 39 . 1 2Cl 2e ) ( Cl 2 = + + - - E (aq) aq 222 . 0 (aq) OH 2 Cu 2e ) ( Cu(OH) 2 - = + + - - - E (s) s 612 . 1 2Cl Cu 2 ) ( Cl 2Cu 2 = + + - + E (aq) (aq) aq (s) kJ 311 )(1.612)
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Unformatted text preview: 10-2(9.649-nFE G 4-= = = ( 29 54 ) 05916 . /( ) 582 . 1 )( 2 ( 05916 . / 10 14 . 3 10 10 = = = nE K It is spontaneous 2) A 250 mL unknown sample of V 3+ was titrated with 42.4 mL of 0.03 M EDTA to excess. The EDTA was back titrated with 14.3 mL 0.01 M Zn 2+ . What was the concentration of vanadium in the unknown solution? EDTA excess mol 10 43 . 1 L) M)(0.0143 01 . ( Zn mol 4 2 = = =-+ EDTA mol 10 272 . 1 L) M)(0.0424 03 . ( EDTA mol 3 = = =-3 4 3 3 10 13 . 1 10 43 . 1 10 272 . 1 used EDTA mol V mol---+ = - = = [ ] M 10 5 . 4 L 250 . mol 10 13 . 1 3 3 3--+ = = V...
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## This note was uploaded on 12/10/2008 for the course CHEMISTRY CHEM 3600 taught by Professor Philipj.silva during the Fall '07 term at Uni. Tartu.

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