ch6 solutions

ch6 solutions - Questions on Concepts Q6.1) Under what...

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89 Questions on Concepts Q6.1) Under what conditions is 0 dA a condition that defines the spontaneity of a process? This is the case at constant T and V if no nonexpansion work is possible. Q6.2) Under what conditions is 0 dG a condition that defines the spontaneity of a process? This is the case at constant T and P if no nonexpansion work is possible. Q6.3) Which thermodynamic state function gives a measure of the maximum electric work that can be carried out in a fuel cell? G because nonexpansion dG dw ≤/ Q6.4) By invoking the pressure dependence of the chemical potential, show that if a valve separating a vessel of pure A from a vessel containing a mixture of A and B is opened, mixing will occur. Both A and B are ideal gases, and the initial pressure in both vessels is 1 bar. The chemical potential of A in the mixture than in the pure gas because () ( ) ,l n A AA P TP T RT P µµ =+ o o , and P A < P º. Because mass flows from regions of high chemical potential to regions of low chemical potential, pure A will flow into the mixture, and the contents of both vessels will be mixed. Q6.5) Under what condition is K P = K x ? This is the case for a reaction involving gases if n = 0. Q6.6) It is found that K P is independent of T for a particular chemical reaction. What does this tell you about the reaction? This is true if H reaction = 0. Q6.7) The reaction A + B C + D is at equilibrium for ξ = 0.1. What does this tell you about the variation of G pure with ξ ?
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90 It tells you that f G o for A + B is less than that for C + D. If the f G o of reactants and products were nearly the same, ξ would be near 0.5. If the f G o for the products were less than those for the reactants, would be near 1. Q6.8) The reaction A + B C + D is at equilibrium for ξ = 0.5. What does this tell you about the variation of G pure with ? It tells you that f G o for A + B is equal to that for C + D. If the f G o for the products were less than those for the reactants, would be near 1. If the f G o for the reactants were less than those for the products, would be much smaller than 0.5. Q6.9) Why is it reasonable to set the chemical potential of a pure liquid or solid substance equal to its standard state chemical potential at that temperature independent of the pressure in considering chemical equilibrium? The pressure dependence of G for solids and liquids is very small, because the volume of liquids and solids changes very little unless very high pressures are applied. Therefore, it is a good approximation to set the chemical potential of a pure liquid or solid substance equal to its standard state chemical potential at the temperature of interest. Q6.10) Is the equation T UT P V β κ ∂− ⎛⎞ = ⎜⎟ ⎝⎠ valid for liquids, solids, and gases?
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ch6 solutions - Questions on Concepts Q6.1) Under what...

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