## Exothermic vs Endothermic

Arrhenius Equation: $\ln k = - \frac{E_{a}}{RT} + \ln A$

Jaira_Murphy_2D
Posts: 31
Joined: Fri Apr 06, 2018 3:00 am

### Exothermic vs Endothermic

How can you tell if a reaction is endothermic or exothermic based off Arrhenius equation, or given Ea and k?

PranitKumaran1F
Posts: 30
Joined: Thu Nov 08, 2018 12:17 am

### Re: Exothermic vs Endothermic

If the Ea of the forward rxn is greater than the Ea of the reverse rxn, then it is endothermic and vise versa

hanna_maillard3B
Posts: 61
Joined: Fri Sep 28, 2018 12:23 am

### Re: Exothermic vs Endothermic

so to clarify, if a higher activation energy is needed for the forward reaction compared to the reverse reaction, then the reaction is endothermic ?

Jaira_Murphy_2D
Posts: 31
Joined: Fri Apr 06, 2018 3:00 am

### Re: Exothermic vs Endothermic

I love chemistry community because everyone replies so fast!

Lydia Luong 4L
Posts: 59
Joined: Fri Sep 28, 2018 12:24 am

### Re: Exothermic vs Endothermic

Yes, you are correct @hanna_maillard3B

Milena Aragon 2B
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

### Re: Exothermic vs Endothermic

A higher activation energy means that the reaction requires a higher temperature to move in the forward direction and since this is the case you can conclude that the reaction is endothermic (since it is using the heat from the temp. to move the reaction forward). From this you know that the reverse is true for exothermic reactions

Jack Hewitt 2H
Posts: 67
Joined: Fri Sep 28, 2018 12:27 am

### Re: Exothermic vs Endothermic

Ea forward > Ea Reverse: Endothermic
Ea forward < Ea Reverse: Exothermic