Using reaction free energy to predict equilibrium composition

Using reaction free energy to predict equilibrium composition

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Using reaction free energy to predict equilibrium composition Remember that the reaction free energy Δ G determines whether the forward or reverse reaction is spontaneous This is not the same as the standard reaction free energy Δ G , which only determines the spontaneous reaction at standards states. The relationship is given by is the gas constant in units of J/K = 8.3145 J*mol -1 *K -1 (use when P is in Pa and V is in m 3 =0.08206 L*atm*mol -1 *K -1 You can ignore all of this calculation if you just use some intuition to figure out the sign of
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Unformatted text preview: Δ G. Consider the reaction quotient: If Q is very large, then Δ G is very large and positive. I.e. the reverse reaction is spontaneous, and the pressure of the product will tend to fall We see that changing the value of the pressure of a reactant will change the sign of Δ G. e.g. If P becomes large, then Q becomes small, so Δ G becomes large and negative To find if the specific minimum pressure of a reactant that changes the sign of Δ G, solve for Q in eqn (1) above; then solve for P reactant in eqn (2)...
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This note was uploaded on 01/24/2012 for the course CHEM 152 taught by Professor Chiu during the Fall '08 term at University of Washington.

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