But more importantly is something called free energy G = H - TS want G to be negative, so that the free energy of the universe decreases, this is a spontaneous.

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Presentation transcript:

But more importantly is something called free energy G = H - TS want G to be negative, so that the free energy of the universe decreases, this is a spontaneous reaction = spontaneous

G = H - TS = spontaneous - + = spontaneous at high temp - = spontaneous at low temp - + = not!spontaneous + check pg Spont. At low temp Spont. At high temp spontane ous Not spont

so... if the reaction is exothermic, giving off - 45 kj heat and the temperature is 290 K, the entropy is + 30, what is the free energy, and is the reaction spontaneous?

so... if the reaction is exothermic, giving off - 45 kj heat and the temperature is 290 K, the entropy is + 30, what is the free energy, and is the reaction spontaneous? G = H - TS H T S want it to be negative

so... if the reaction is exothermic, giving off - 45 kj heat and the temperature is 290 K, the entropy is + 3.0, what is the free energy, and is the reaction spontaneous? G = H - TS H T S want it to be negative G = ( 290 * 3.0) G = (870) G = -915, so this is spontaneous!

How do you know the # for ΔS surr? ΔS surr = ΔH T temp in kelvin ΔS system = Σ np S products - Σ np S reactants