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Identifying endothermic vs exothermic

Posted: Sun Jan 19, 2020 4:57 pm
by 405318478
If a problem doesn't specifically state if it is endothermic or exothermic, how do we determine which it is based off the stoichiometric equation?

Re: Identifying endothermic vs exothermic

Posted: Sun Jan 19, 2020 5:04 pm
by Elena Bell 1C
A reaction is exothermic if the products have more energy than the reactants, and it is endothermic if the reactants have more energy than the products. Usually, the reaction would give you a deltaH value if it is asking about temperature. DeltaH would be negative if the reaction is exothermic and positive if it is endothermic.

Re: Identifying endothermic vs exothermic

Posted: Sun Jan 19, 2020 5:06 pm
by Eugene Chung 3F
Elena Bell 1C wrote:A reaction is exothermic if the products have more energy than the reactants, and it is endothermic if the reactants have more energy than the products. Usually, the reaction would give you a deltaH value if it is asking about temperature. DeltaH would be negative if the reaction is exothermic and positive if it is endothermic.


This because energy is absorbed in form of heat in an endothermic reaction and energy is released in exothermic reaction.
Endothermic absorbs heat, and exothermic produces heat.

Re: Identifying endothermic vs exothermic

Posted: Sun Jan 19, 2020 5:40 pm
by san_2F
When delta H is negative, it's exothermic and when delta H is positive, the reaction is endothermic.

Re: Identifying endothermic vs exothermic

Posted: Sun Jan 19, 2020 9:41 pm
by Noe BM 1J
If delta H is negative, it means that the reaction is exothermic (it releases energy). If delta H is positive, the reaction is endothermic (it requires energy).

Re: Identifying endothermic vs exothermic

Posted: Sun Jan 19, 2020 11:42 pm
by Ruth Glauber 1C
Check if the products have more energy than the reactants to decide if its exothermic!

Re: Identifying endothermic vs exothermic

Posted: Mon Jan 20, 2020 3:26 am
by Sanjana K - 2F
You can also look at bond enthalpies or use Hess's Law to figure out the total energy on the reactants and products side or the energy needed to form/break the bonds and if delta H < 0, it's exothermic and if delta H > 0, it's endothermic.

Re: Identifying endothermic vs exothermic

Posted: Mon Jan 20, 2020 7:58 am
by Mitchell Koss 4G
They will need to give you a delta H, so it it is positive, reaction is endothermic, but if it is negative, it is exothermic.