Exothermic reaction

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Kim Vu 2G
Posts: 29
Joined: Fri Sep 25, 2015 3:00 am

Exothermic reaction

Postby Kim Vu 2G » Mon Jan 11, 2016 10:58 pm

Why is it that when the temperature increases in an enthalpy problem, it is an exothermic reaction instead of endothermic?Wouldn't the increase from initial to final temperature make the system endothermic because heat is being absorbed by the system?

Amelia Vernon 2L
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

Re: Exothermic reaction

Postby Amelia Vernon 2L » Mon Jan 11, 2016 11:23 pm

In the thermodynamic reaction Dr. Lavelle showed in class, the reaction increased from 25°C to 31.9°C (if this was the temp increase you were referring to). However, a new bond was being formed (in the H2O from the H+ and OH-) which makes the whole reaction exothermic, regardless of the temp. change since bond formation is ALWAYS exothermic. Hope this helps.

Bryan Lau 3H
Posts: 53
Joined: Fri Sep 25, 2015 3:00 am

Re: Exothermic reaction

Postby Bryan Lau 3H » Mon Jan 11, 2016 11:30 pm

To my understanding, the temperature of the SURROUNDING increases in an enthalpy problem, for an exothermic reaction. Heat is being RELEASED by the system (-∆H). I think the increase from initial to final temperature refers to the temperature of the SURROUNDING, because that's what would absorb the heat released (exothermic) by the system.

AngelinaArianaAviles3G
Posts: 10
Joined: Fri Sep 25, 2015 3:00 am

Re: Exothermic reaction

Postby AngelinaArianaAviles3G » Tue Jan 12, 2016 11:54 am

Whenever you are taking in to account whether or not a reaction is endothermic or exothermic, you always put it in the perspective of the system, not the surroundings. So Bryan is correct.
The system is exothermic because it is thus releasing heat in to the surroundings. If you thought about it in its counter, then you could say that the surroundings is considered endothermic since it is absorbing heat released from the system.


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