Question
The negative of the slope of Gibbs free energy vs Temperature graph indicates:
A. Enthalpy change
B. Entropy change
C. Both A and B above.
D. None of these.
▶️Answer/Explanation
B.
As ∆G=∆H-T∆S
∆S is −gradient.
Question
Entropy of the system is greatest for?
A. Gas
B. Liquid
C. Solid
D. All have equal entropy.
▶️Answer/Explanation
A.
Entropy of the system Gas>Liquid>Solid.
Question
The graph shows values of ΔG for a reaction at different temperatures.
Which statement is correct?
A. The standard entropy change of the reaction is negative.
B. The standard enthalpy change of the reaction is positive.
C. At higher temperatures, the reaction becomes less spontaneous.
D. The standard enthalpy change of the reaction is negative.
▶️Answer/Explanation
B
∆H represents y-axis intercept. Which is positive here, hence the standard enthalpy change of the reaction is positive.
∆S is −gradient. If ∆S is a constant value>0, then ∆G decreases as T increases as a result of increasing positive product of T∆S: this is observed as graph with a negative gradient slope.
∆G decreases and becomes more negative as T increases which means at higher temperatures, the reaction becomes more spontaneous.