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Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium

Chapter 18, Problem 134

Suppose that a reaction has ΔH = - 33 kJ and ΔS = - 58 J>K. At what temperature will it change from spontaneous to nonspontaneous?

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Hello everyone today. We have the following problem. A reaction has a change in entropy of positive 40 kg jewels and a change of entropy of 115 joules per kelvin calculate the crossover temperature for the reaction. So what is the cross over temperature for? The crossover temperature is simply the temperature where our change in our gibbs. Free energy is equal to zero. And essentially the sign changes when we cross this temperature. So first we want to recall our equation for gibbs. Free energy gives free energy we said was gonna equal zero and this is going to equal our change in our in therapy minus our temperature times our change in entropy And so our change and are in therapy was said to be positive 40 kg jewels. We don't have our temperature and then we're gonna sit and we're gonna multiply this By 1. 15 jewels per Kelvin. What we also want to make sure we do is we want to convert our killer jewels into regular jewels to get rid of this unit of jewels for our entropy. So we are going to take our 40 killed jules And we're going to multiply by the conversion factor that one killer jewel has 10 to the third jewels. And then plug in the rest of our formula here, Solving for a temperature we get a temperature of 340 8° Kelvin has our final crossover temperature overall, I hope this helped. And until next time
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