Lecture 7 - A positive voltage means the reaction proceeds forward(as written Negative means reverse reaction is spontaneous Charge(uphill

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Redox reactions that give max voltage are choosing reactions between elements that are willing to give up electrons and elements that aren’t but are willing to accept electrons. When you examine a periodic table, you will find that (excluding the noble gases) the electronegativity values tend to increase as you go to the right and up. The reverse statement is that the values tend to decrease going down and to the left. This pattern will help when you are asked to put several bonds in order from most to least ionic without using the values themselves Reversing reaction will change sign of standard potential. Always write as reduction though… Multiplying a reaction by a coefficient does not change the free energy (i.e. the standard voltage)
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Unformatted text preview: A positive voltage means the reaction proceeds forward (as written). Negative means reverse reaction is spontaneous. Charge (uphill direction, negative voltage) and discharge (downhill, positive voltage) dG=(-1)nF(dE) n=number mole electrion, F=Faraday constant (96485.3365 Coulombs/mole), dE=potential In a battery, the more use will build up the Zn+2 concentration on the anode side, and reduce the Cu+2 concentration on the cathode side, slowing down the potential. If you put the zinc anode in the copper solution, voltage will still be produced, it just won’t be captured. Copper will build up on zinc anode… the electrons go straight from zinc to the copper building up on it....
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This note was uploaded on 01/16/2012 for the course ENVIRON 404 taught by Professor Rasmussen during the Fall '11 term at University of Michigan.

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