Endothermic and Exothermic

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ng1D
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Endothermic and Exothermic

Postby ng1D » Sat Jan 25, 2020 9:21 am

How do you tell whether a reaction is endothermic or exothermic by the direction of heat flow?

Fiona Latifi 1A
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Re: Endothermic and Exothermic

Postby Fiona Latifi 1A » Sat Jan 25, 2020 11:19 am

Endothermic reactions use heat as a reactant because they require energy. Exothermic reactions use heat as a product because they release energy.

Rebekah Alfred 1J
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Re: Endothermic and Exothermic

Postby Rebekah Alfred 1J » Sat Jan 25, 2020 11:39 am

Fiona Latifi 1A wrote:Endothermic reactions use heat as a reactant because they require energy. Exothermic reactions use heat as a product because they release energy.

This might be a helpful visual to see the role heat/energy plays in endothermic and exothermic reactions:
Image

Izzie Capra 2E
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Re: Endothermic and Exothermic

Postby Izzie Capra 2E » Sat Jan 25, 2020 1:22 pm

Endothermic reactions absorb heat and use heat as a reactant. This way, the surrounding become cool because heat was absorbed in the reaction. Basically, heat goes in. Exothermic reactions release heat (heat is a product), which makes the surroundings warm. Here, heat goes out.

Sartaj Bal 1J
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Re: Endothermic and Exothermic

Postby Sartaj Bal 1J » Sat Jan 25, 2020 1:59 pm

Endothermic reactions usually have a positive Delta H which signifies that heat is absorbed while exothermic reactions usually have a negative Delta H which signifies that heat was released during the competition of the reaction.

EllieSchmidtke_4I
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Re: Endothermic and Exothermic

Postby EllieSchmidtke_4I » Sat Jan 25, 2020 3:22 pm

To proceed in the forward direction, endothermic systems require heat while exothermic systems release heat.

Jamie Lee 1F
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Re: Endothermic and Exothermic

Postby Jamie Lee 1F » Sat Jan 25, 2020 5:04 pm

You can think of heat as either a reactant or a product. When heat is being released, the reaction is exothermic, and heat is product. Conversely, when heat is being absorbed, a reaction is endothermic, and heat is a reactant.

Diana Chavez-Carrillo 2L
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Re: Endothermic and Exothermic

Postby Diana Chavez-Carrillo 2L » Sat Jan 25, 2020 5:15 pm

In an endothermic reaction, heat is being absorbed so you can think of it as a reactant. In an exothermic reaction, heat is being released so you can think of it as a product. You can usually tell whether a reaction is endothermic or exothermic by looking at the given enthalpy. If the enthalpy is a positive number then its endothermic. If the enthalpy is a negative number then this reaction is exothermic. Here is a Khan Academy link that I think is very helpful in breaking down these types of reactions:

https://www.khanacademy.org/test-prep/m ... -reactions

Essentially,
ΔH value negative –> energy released –> exothermic reaction
ΔH value positive --> energy absorbed --> endothermic reaction

805329408
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Re: Endothermic and Exothermic

Postby 805329408 » Sat Jan 25, 2020 5:25 pm

If heat is flowing out, the reaction is exothermic, and if heat is being absorbed, the reaction is endothermic. A trick I like to use to remember this is by looking at the first two letters of each word, in "exothermic" heat is "EXiting" and in "endothermic" heat is "ENtering". Hope this helps!

J Medina 2I
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Re: Endothermic and Exothermic

Postby J Medina 2I » Sat Jan 25, 2020 6:18 pm

If you have trouble deciding whether a reaction is endothermic or exothermic based on direction of heat flow, I find it helpful to think of the melting of ice as an example. Ice melting into liquid water is an ENDOTHERMIC reaction. The ice's surrounding has to be warm in order for liquid water to be formed because the ice cube is taking in the energy ( + change) from the outside to form liquid water. This makes it easy to remember that water has a positive increase in enthalpy ( + ΔH ) when it is melted, which also applies to all endothermic reactions.

san_2F
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Re: Endothermic and Exothermic

Postby san_2F » Sat Jan 25, 2020 6:27 pm

Endothermic reactions require heat in chemical reactions and delta H is positive whereas exothermic reactions release heat in chemical reaction and delta H is negative.

Robert Tran 1B
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Re: Endothermic and Exothermic

Postby Robert Tran 1B » Sat Jan 25, 2020 6:28 pm

In an endothermic reaction, the reaction removes heat from the surroundings. In an exothermic reaction, the reaction adds heat to the surroundings. However, all reactions take some heat to begin (activation energy), so the previous statements are based on net changes.

Kayla Maldonado 1C
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Re: Endothermic and Exothermic

Postby Kayla Maldonado 1C » Sat Jan 25, 2020 6:59 pm

Endothermic Reactions require heat or absorb it to overcome the activation energy to form products. In an exothermic reaction, heat is released or "exits" the reaction to form the product and no longer can overcome the activation energy in the reverse reaction unless more heat is absorbed.

Max Madrzyk Dis 4G
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Re: Endothermic and Exothermic

Postby Max Madrzyk Dis 4G » Sat Jan 25, 2020 7:15 pm

If the reaction needs heat to be work then you can think of heat being considered as a reactant and therefore the reaction is endothermic because the products are using the heat to form. If the reaction produces heat then you can think of heat as a product and therefore it would an exothermic reaction.


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