Homework ESM219_1_F07

# Homework ESM219_1_F07 - HOMEWORK ESM 219, Fall 2007 Due:...

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HOMEWORK ESM 219, Fall 2007 Due: 11-5-07 1. Microbial Energetics A particular phenol mineralizing bacteria is versatile in its use of electron acceptors. In oxic environments, it uses oxygen; in anoxic environments, it uses nitrate and denitrifies; in anaerobic environments, it uses ferric iron. a. If we assume that yield proportional to available energy, which environments would contain a larger population of the bacteria (all else being equal)? Base your answers on calculations of free energy of the three different reactions carried out (see the APPROACH). b. Is this the “real” energy yielded during the microbial reaction? Why or why not? c. Comment for the anoxic and anaerobic environments how the total reaction might alter the local pH. Oxidation half rxn: e H CO H H C O O - + + + → + 2 2 6 6 28 6 28 11 28 1 Reduction half rxns: For aerobic metabolism, the Reduction half rxn is: e 2 H 2 O 2 1 O H 2 2 - + + + For the anoxic condition, where denitrification is occurring, the reduction half rxn is: O H N e H O N 2 2 3 5 3 10 1 5 6 5 1 + → + + - + - For the anaerobic condition, where trivalent iron is the terminal electron acceptor: Reduction half rxn: Fe e Fe 2 3 + - + → + APPROACH: Set up this problem as 3 parts. For the first part, couple the oxidation half reaction with the reduction half reaction for aerobic metabolism. Note that for this first part, you must first balance the charge by multiplying the entire reduction half reaction

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## This note was uploaded on 08/06/2008 for the course ESM 219 taught by Professor Holden during the Fall '07 term at UCSB.

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Homework ESM219_1_F07 - HOMEWORK ESM 219, Fall 2007 Due:...

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