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Enthalpy signs

Posted: Sat Jan 26, 2019 9:20 pm
by Nicole Garrido 2I
When is the change in H, Enthalpy, positive and when is it negative?

Re: Enthalpy signs

Posted: Sat Jan 26, 2019 9:39 pm
by Searra Harding 4I
Enthalpy will be positive when the reaction is endothermic meaning it absorbs heat. It is negative when the reaction is exothermic meaning giving off heat.

Re: Enthalpy signs

Posted: Sat Jan 26, 2019 10:24 pm
by Anjali_Kumar1F
What is state property and what does it mean when enthalpy is state property.

Re: Enthalpy signs

Posted: Sat Jan 26, 2019 10:36 pm
by Rami_Z_AbuQubo_2K
When deltaH is positive, that mean that the reaction is going to absorb heat in order to proceed and is endothermic. When deltaH is negative, that means that the reaction is going to release heat into the environment and is exothermic.

Re: Enthalpy signs

Posted: Sun Jan 27, 2019 5:01 pm
by davidryan3f
Delta H is positive when the reaction is endothermic and Delta H is negative when the reaction is exothermic.

Re: Enthalpy signs

Posted: Sun Jan 27, 2019 9:06 pm
by KarlaArevalo2F
enthalpy is positive for endothermic because there is the need for heat, while enthalpy is negative for exothermic because heat is being released (exo=exit)

Re: Enthalpy signs

Posted: Sun Jan 27, 2019 9:06 pm
by KarlaArevalo2F
enthalpy is positive for endothermic because there is the need for heat, while enthalpy is negative for exothermic because heat is being released (exo=exit/out)

Re: Enthalpy signs

Posted: Sun Jan 27, 2019 9:30 pm
by Diana Sandoval 1K
If it's positive it's endothermic and if it's negative it's exothermic.

Re: Enthalpy signs

Posted: Sun Jan 27, 2019 10:38 pm
by Anand Narayan 1G
When Delta H is positive, it's endothermic and when it's negative, it's exothermic

Re: Enthalpy signs

Posted: Mon Jan 28, 2019 10:03 am
by deepto_mizan1H
Another aspect of this is thinking of the heat as a product or reactant, where in an endothermic reaction (+) it would require heat which can be considered as a reactant. In an exothermic reaction (-), where heat is given off, we can think of it as a product.

Re: Enthalpy signs

Posted: Mon Jan 28, 2019 10:49 am
by Jordan Lo 2A
deepto_mizan1H wrote:Another aspect of this is thinking of the heat as a product or reactant, where in an endothermic reaction (+) it would require heat which can be considered as a reactant. In an exothermic reaction (-), where heat is given off, we can think of it as a product.


This strategy is also helpful when thinking about le chatelier's principle and heat added/taken away to the system

Re: Enthalpy signs

Posted: Mon Jan 28, 2019 12:33 pm
by Tinisha 1G
Enthalpy is the amount of heat absorbed in a reaction. If the reaction is endothermic, it absorbs heat, so the sign of enthalpy is therefore postitive. It is negative if the reaction is exothermic, and so it is releasing heat, therefore is going to have a negative enthalpy.

Re: Enthalpy signs

Posted: Mon Jan 28, 2019 3:48 pm
by Jason Ye 2I
Its positive when the reaction is endothermic and negative when it is exothermic

Re: Enthalpy signs

Posted: Tue Jan 29, 2019 7:45 pm
by George Ghaly 2L
The enthalpy change is positive when a reaction gains heat (endothermic reaction) and is negative when the reactants release energy to the universe (exothermic reactions)