36 kj 0 kj 13717 kj 18893 kj 6826

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Unformatted text preview: calculate the reaction free energy from the formation free energies for each 193 substance. To calculate the equilibrium constant at any temperature of interest, we make use of the Gibbs- Helmholtz equation. ) # Δ G∅ & , ) # G &, + ∂% R (. + ∂% (. T '. % ( Δ H∅ + $ T '. = − H ⇒ + $ =− R + ∂T . 2 2 + ∂T . T T + . + . + . * -P * -P Then we make use of the relationship between ΔRG and Keq to obtain: ∅ € # ∂ ln K eq & Δ RH∅ % (= ∂T ' RT 2 $ P which, if we assume ΔRH to be independent of temperature, leads to: € ( )( ) ln K eq [ T2 ] − ln K eq [ T1] −Δ RH∅ % 1 1 ( = ' − * R & T2 T1 ) So we conclude that Keq increases with temperature if the reaction is € endothermic (positive value for ΔRH ). Obviously, if the reaction is ∅ exothermic, an increase in temperature leads to a decrease in the equilibrium constant....
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This note was uploaded on 01/26/2014 for the course CHEM 3615 taught by Professor Aresker during the Spring '07 term at Virginia Tech.

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