In: Chemistry
Given the values of ΔH∘rxn, ΔS∘rxn, and T below, determine ΔSuniv.
Predict whether or not each reaction will be spontaneous.
ΔH∘rxn=− 118 kJ , ΔS∘rxn= 261 J/K , T= 294 K
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ΔSuniv = ??? (J/K) |
ΔH∘rxn= 118 kJ , ΔS∘rxn=− 261 J/K , T= 294 K .
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ΔSuniv = ??? (J/K) ΔH∘rxn=− 118 kJ , ΔS∘rxn=− 261 J/K , T= 294 K .
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ΔH∘rxn=− 118 kJ , ΔS∘rxn=− 261 J/K , T= 565 K .
ΔSuniv = ??? (J/K)
ANSWER : (S)universe = (S)system + (S)surrounding [From thermodynamics]
(S)system = +261KJ/mol ; (S)surrounding = [(- H)system] / T & Hsystem = -118KJ/mol
T = temperature = 294 K
==> (S)universe = 261 + - (-118) /294 = 261 + 118/294
= 261 + 0.401 =261.401 KJ/mol
(S)universe = 261.401 KJ/mol { in this case reaction is not spontaneous as entopychange is positive}