## Exothermic vs. Endothermic?!

Ben Rolnik 1D
Posts: 33
Joined: Fri Jun 23, 2017 11:39 am

### Exothermic vs. Endothermic?!

Can someone help me understand the difference between Exothermic and Endothermic (as well as how we use this to make chemical equilibrium calculations). For some reason, it reads like a brain teaser to me!

Thank you!
Ben

Gwyndolyn
Posts: 23
Joined: Wed Nov 16, 2016 3:03 am

### Re: Exothermic vs. Endothermic?!

Endothermic means that the reaction requires heat, and exothermic means it expels heat during the reaction. To help remember, you can think of, for exothermic, the heat is exiting the system.
I'm not exactly sure what you mean about the chemical equilibrium calculations part, but another helpful thing to remember: professor Lavelle talked about how if a forwards reaction is endothermic then the reverse reaction is exothermic, and vise versa(if a forward reaction is exothermic then the reverse reaction is endothermic). Furthermore, if a forward reaction is endothermic, heating will favor forward reactions(formation of products), whereas for an exothermic forward reaction heating will favor the reverse reaction(formation of reactants).
Hope this helps!

Aliza Ajmal 1D
Posts: 25
Joined: Fri Sep 29, 2017 7:05 am

### Re: Exothermic vs. Endothermic?!

I don't know if you need to know this, but a problem in the Ch.11 homework distinguished exothermic and endothermic using Gibbs Free Energy (delta G). An exothermic reaction has a negative delta G and and endothermic reaction has a positive delta G. I think the main idea you need to know is that exothermic releases energy and endothermic requires and absorbs energy. Exothermic reactions will have lots of energy on the right side (products side) so according to Le Chatelier's Principle, the reaction will want to balance out the energy on both sides. In order to balance an exothermic reaction, the reaction will create more reactants to balance the energy on both sides. If the reaction is endothermic (energy on the left), then the reaction will produce more products to balance the energy equally on both sides. I hope this was helpful!

Vasiliki G Dis1C
Posts: 53
Joined: Fri Sep 29, 2017 7:04 am

### Re: Exothermic vs. Endothermic?!

Endothermic reactions will have a positive ΔH, because heat is being added, and exothermic reactions will have a negative ΔH, since heat is being released. If you see a positive ΔH value associated with the reaction and the temperature is increased, this will favor the formation of products. If you see a negative ΔH value associated with the reaction and the temperature is increased, this will favor the formation of reactants.

Sarah Rutzick 1L
Posts: 50
Joined: Tue Oct 10, 2017 7:13 am

### Re: Exothermic vs. Endothermic?!

Sometimes it helps me to think of heat as a reactant or product. If heat is added to the reactant side (endothermic) then more products will be produces, and if heat is added to the product side (exothermic) then more reactants will be produced.

Sarah Rutzick 1L
Posts: 50
Joined: Tue Oct 10, 2017 7:13 am

### Re: Exothermic vs. Endothermic?!

Sometimes it helps me to think of heat as a reactant or product. If heat is added to the reactant side (endothermic) then more products will be produces, and if heat is added to the product side (exothermic) then more reactants will be produced.

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