Which of These Reactions Are Spontaneous?

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SUMMARY

The discussion focuses on determining the spontaneity of five chemical reactions based on their enthalpy (ΔH) and entropy (ΔS) values at constant temperature (T) and pressure (P). The key criterion for spontaneity is the Gibbs free energy change (ΔG), calculated using the equation ΔG = ΔH - TΔS. The only spontaneous reaction among the options provided is (a) ΔH = -10 kJ, ΔS = +5 J/K at T = 298K, as it results in a negative ΔG value, indicating that it is both exothermic and increases disorder.

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parwana
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Which of these is spontaneous??

Which of the following are spontaneous at constant T and P ?


(a) DH = -10 KJ DS = +5 J/K T = 298K

(b) DH = +5 KJ DS = -5 J/K T = 10K

(c) DH = -10 KJ DS = -40 J/K T = 300K

(d) DH = -10 KJ DS = -40 J/K T = 200K

(e) DH = -10 KJ DS = -40 J/K T = 500K


DH= enthalpy

DS= entropy

all i know about spontaneous reactions is that entropy is greater than zero, and gibbs free energy is negative. Help with this one.
 
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Solve for delta G, find the equation in your text.
 
isnt it choice "A", since that one is giving off energy (exothermic) and it is becomming more dissordered (enthropy is increasing). All the rest are either taking in energy (endothermic) and/or enthropy is decreasing.
just being exothermic itself isn't enough to be spontaneous but it is a good sign, but when enthropy is increasing that does. or am I wrong.
 
That's not right jeffy, spontanaeity is determined by the free energy, not the enthalpy.
 
parwana said:
Which of the following are spontaneous at constant T and P ?


(a) DH = -10 KJ DS = +5 J/K T = 298K

(b) DH = +5 KJ DS = -5 J/K T = 10K

(c) DH = -10 KJ DS = -40 J/K T = 300K

(d) DH = -10 KJ DS = -40 J/K T = 200K

(e) DH = -10 KJ DS = -40 J/K T = 500K


DH= enthalpy

DS= entropy

all i know about spontaneous reactions is that entropy is greater than zero, and gibbs free energy is negative. Help with this one.

You've virtually been told everything you need to do. I can't imagine where your difficulty lies.
 

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