Endothermic and Exothermic Reactions

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Blake Ballew 1H
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Joined: Wed Sep 30, 2020 9:35 pm

Endothermic and Exothermic Reactions

Postby Blake Ballew 1H » Sun Jan 10, 2021 12:44 pm

What is it about the endothermic reactions requiring heat to form products that makes it favor product formation and vice versa for exothermic reactions? I don't think I entirely understand this whole concept of temperature as it relates to product and reactant formation. Any help would be greatly appreciated!

Stuti Pradhan 2J
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Re: Endothermic and Exothermic Reactions

Postby Stuti Pradhan 2J » Sun Jan 10, 2021 12:49 pm

I think the main concept to understand with endothermic and exothermic reactions is that endothermic reactions require heat to form the products and exothermic reactions release heat. If heat was added to an endothermic reaction, then more products would be formed (product formation would be favored) as more heat will allow the reaction to proceed. However, if heat was added to an exothermic reaction, more reactants would be formed to reduce the change since heat is released in this situation, and forming more reactants will require heat, which will reduce the heat in the system.

Hope this helps!

Simrah_Ahmed1J
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Re: Endothermic and Exothermic Reactions

Postby Simrah_Ahmed1J » Sun Jan 10, 2021 1:03 pm

To put it simply, it is based on the energy level of the reactants and products. This is why we measure it with enthalpy (H) which is related to heat energy. The attached drawings of graphs is from my notes on one of the lectures, it might help make sense of the idea.
So basically, a reaction is exothermic in the forward direction when it gives off heat because the reactants are at a higher energy level than the products. So. if you add energy in the form of heat, it will help you go in the reverse direction and make more reactants since they are at a higher energy level. Instead, cooling will help you make more products.
Then, a reaction is endothermic in the forward direction when it absorbs heat because the reactants are at a lower energy level than the products. So if you add some energy in the form of heat, it will help you make more products since they are at a higher energy level.
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Rose_Malki_3G
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Re: Endothermic and Exothermic Reactions

Postby Rose_Malki_3G » Sun Jan 10, 2021 1:23 pm

If you have an endothermic reaction, then you can think of heat as a reactant so if you were to release heat, the reaction would shift to the left whereas if you increase heat, it would favor the products/forward reaction.

705512695
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Re: Endothermic and Exothermic Reactions

Postby 705512695 » Sun Jan 10, 2021 1:29 pm

Simrah_Ahmed3F wrote:To put it simply, it is based on the energy level of the reactants and products. This is why we measure it with enthalpy (H) which is related to heat energy. The attached drawings of graphs is from my notes on one of the lectures, it might help make sense of the idea.
So basically, a reaction is exothermic in the forward direction when it gives off heat because the reactants are at a higher energy level than the products. So. if you add energy in the form of heat, it will help you go in the reverse direction and make more reactants since they are at a higher energy level. Instead, cooling will help you make more products.
Then, a reaction is endothermic in the forward direction when it absorbs heat because the reactants are at a lower energy level than the products. So if you add some energy in the form of heat, it will help you make more products since they are at a higher energy level.


This is really helpful thank you!

Emma_Barrall_3J
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Re: Endothermic and Exothermic Reactions

Postby Emma_Barrall_3J » Sun Jan 10, 2021 1:52 pm

I think it is important to remember that in a reversible reaction: if the forward reaction is endothermic (absorbs heat), the reverse reaction is exothermic (releases heat). Adding heat will favor the "endothermic arrow" whether that be forward or reverse.

Carolina Gomez 2G
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Re: Endothermic and Exothermic Reactions

Postby Carolina Gomez 2G » Sun Jan 10, 2021 2:20 pm

If a reaction is endothermic, meaning it requires heat to form products, then heating will favor product formation, but removing heat will favor reactant formation.
An example of an endothermic reaction is photosynthesis since the reactants are being combined to from glucose, in which the reaction needs energy (heat) to form the glucose. Therefore, the heating favors product formation.

If a reactions is exothermic, meaning it gives of heat while forming products, then cooling will favor product formation, but adding heat will favor reactant formation.
An example of an exothermic reaction is the hydrolysis of ATP. While ATP is being broken down it releases heat, therefore the cooling favors the product formation.


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