# Gibbs Free Energy help

by Swerting
Tags: energy, free, gibbs
 P: 35 1. The problem statement, all variables and given/known data The reaction is $$NH_{4}Cl(s)\rightarrow NH_{3}(g)+HCl(g)$$ $$\Delta H^{o}=+176 kJ and \Delta G^{o}=+91.2 kJ$$ at 298 K What is the value of $$\Delta G$$ at 1000 K? 2. Relevant equations $$\Delta G=\Delta H-T\Delta S$$ The same applies if all 'deltas' are standard 3. The attempt at a solution Well, I solved for standard change of entropy ($$\Delta S^{o}$$) and came up with .284 kJ/K, which is the same when using a table of standard entropies. My problem is, I'm not sure where to go from this to find $$\Delta G$$, or even a way to link standard values to normal values for these. I tried plugging in the values for standard delta H and delta S with 1000K to find delta G, but something tells me that this is incorrect. Any help would be greatly appreciated! -Swerting
 Sci Advisor HW Helper PF Gold P: 2,532 Gibbs Free Energy help Do you know how to calculate changes in $\Delta H$ and $\Delta S$ with temperature? (Hint: it involves the heat capacity.) Alternatively, you could look up these values at 1000 K.
 P: 35 I can calculate $$\Delta H$$ from changes in temperature, but unfortuneately, not $$\Delta S$$, nor could I find a table of entropies at 1000K.