Exothermic Reactions

Briana Yik 1H
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Exothermic Reactions

How do I find out if a reaction is exothermic or endothermic? Thank you!

Sarah Kiamanesh 1D
Posts: 30
Joined: Fri Sep 28, 2018 12:22 am

Re: Exothermic Reactions

You basically need to know the enthalpies of all the products and reactants. These are set values provided in tables.
If the sum of the enthalpies of the reactants is greater than those of the products, the reaction will be exothermic. It releases energy into the system.
If the sum of the enthalpies of the products is greater than those of the reactants, the reaction will be endothermic. It absorbs energy.

Christopher Anisi 2K
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

Re: Exothermic Reactions

They usually provide the delta H of the reaction, which is also known as enthalpy which will described in more detail in lecture. If the delta H, is positive that means that the reaction is endothermic, if the delta H is negative that means that the reaction is exothermic. Depending on whether heat is being added or removed to the respective reactions allows you to tell you how the products and reactants will shift during equilibrium.

Katelyn Pham 4E
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

Re: Exothermic Reactions

Also, if a reaction is exothermic while forming products, then heating will favor reaction formations.

LeannaPhan14BDis1D
Posts: 57
Joined: Fri Sep 28, 2018 12:16 am

Re: Exothermic Reactions

IN the lecture today he wrote/ said
when pressure changes
when k does change
If rxn requires heat (endothermic) while forming product then heating will favor P formation.
If rxn gives off heat (exothermic) while forming product then heating will favor R formation.
hope this helps :)

Nico Edgar 4L
Posts: 32
Joined: Fri Sep 28, 2018 12:19 am

Re: Exothermic Reactions

An exothermic reaction will release energy, so the products have less energy than the reactants. An endothermic reaction will need energy, so the products have more energy then the reactants.

Jonathan Pai 2I
Posts: 121
Joined: Fri Sep 28, 2018 12:27 am

Re: Exothermic Reactions

Stability also relates to exo or endo, such as the HW question using a halogen, which makes us have to know that halogens are stable diatomically, so dissociating to monotomic would have to be endothermic.

Angela Cong 3C
Posts: 69
Joined: Fri Sep 28, 2018 12:25 am

Re: Exothermic Reactions

in the modules he also mentioned you can tell if a reaction is exo or endo by looking at the lewis structure depending on whether or not they form or break bonds

Aiden Atoori 1C
Posts: 67
Joined: Fri Sep 28, 2018 12:24 am

Re: Exothermic Reactions

So if the sum of the enthalpies of the reactants is greater than the products, the reaction will be exothermic.

Hedi Zappacosta 1E
Posts: 66
Joined: Fri Sep 28, 2018 12:27 am

Re: Exothermic Reactions

In lecture, Dr. Lavelle explained that adding heat to an endothermic reaction will favor the formation of products and adding heat to an exothermic reaction will favor the formation of the reactants.

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