Question

question 6 of 7
for a reaction, δh = -286 kj. when is the reaction spontaneous?
a. when tδs < -286 kj
b. when tδs > 0
c. when tδs = 2(-286 kj)
d. when tδs = -286 kj

Explanation:

Step1: Recall the Gibbs - free energy equation

The Gibbs - free energy change $\Delta G=\Delta H - T\Delta S$. A reaction is spontaneous when $\Delta G<0$.

Step2: Substitute the given $\Delta H$ value

Given $\Delta H = - 286\ kJ$, so we have $\Delta G=-286 - T\Delta S$. For the reaction to be spontaneous, $\Delta G<0$, which means $-286 - T\Delta S<0$.

Step3: Solve the inequality for $T\Delta S$

Add $286$ to both sides of the inequality: $-T\Delta S < 286$. Multiply both sides by $- 1$ and reverse the inequality sign, we get $T\Delta S>-286\ kJ$. When $T\Delta S>0$, it satisfies the condition for $\Delta G<0$ since $\Delta H=-286\ kJ$.

Answer:

B. When $T\Delta S > 0$