## 15.65 (b)

$K = \frac{k_{forward}}{k_{reverse}}$

Andy Liao 1B
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

### 15.65 (b)

15.65 For the reversible, one-step reaction 2A ⇌ B + C, the forward rate constant for the formation of B is 265 L.mol^-1.min^-1 and the rate constant for the reverse reaction is 392 L.mol^-1.min^-1. The activation energy for the forward reaction is 39.7 kJ.mol^-1 and that of the reverse reaction is 25.4 kJ.mol^-1. (b) Is the reaction exothermic or endothermic?

Can someone please explain why the reaction is endothermic? How does the statement "the reverse reaction has a lower activation energy barrier than the forward reaction" prove that the reaction is endothermic?

Tanaisha Italia 1B
Posts: 55
Joined: Fri Sep 29, 2017 7:04 am

### Re: 15.65 (b)

I think this image sums up the reason why it is endothermic. Since the reverse reaction has a lower activation energy barrier than the forward reaction, the products have a higher Gibbs free energy than the reactants. This means that the change in free energy is positive, that the forward reaction is not spontaneous, and that heat was added in order to complete the forward reaction. Thus the reaction is endothermic.