Question

At 25C, Kc=3.86*10^-4 for the reaction: 2NOCl(g)-> 2NO(g)+Cl2(g)
delta Hf for NOCl=51.71Kj/mol , and deltaHf for NO=90.25 kJ/mol. Calculate delta S ??

Answer 1

Here is the rough sketch. we want the standard entropy change, so:

* find the standard enthalpy of reaction (deltaH0) from the standard heats of formation.
* find the standard gibbs free energy change from Kc. (delta G0= RT natural log K)
* because deltaG0 = deltaH0 - T deltaS0, we can find deltaS0 by plugging in the enthalpy and gibbs free energy and standard temperature.

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