Signs for entropy


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AlyssaBei_1F
Posts: 99
Joined: Fri Sep 28, 2018 12:17 am

Signs for entropy

Postby AlyssaBei_1F » Mon Feb 11, 2019 2:44 pm

When do you use -delta H/T versus +delta H/T?

ChathuriGunasekera1D
Posts: 78
Joined: Fri Sep 28, 2018 12:17 am

Re: Signs for entropy

Postby ChathuriGunasekera1D » Mon Feb 11, 2019 2:57 pm

Hi! You use the sign based on whatever your given ΔH is. If you aren't sure about that, you can use q and see if the temperature increased or decreased to see if the reaction is endothermic or exothermic. Endothermic reactions absorb heat, and the temperature increases so q is positive and ΔH is positive.

PranitKumaran1F
Posts: 30
Joined: Thu Nov 08, 2018 12:17 am

Re: Signs for entropy

Postby PranitKumaran1F » Mon Feb 11, 2019 3:30 pm

If the reaction is endothermic, you know that delta H is positive because the reaction absorbs heat. If the reaction is exothermic, then delta H would be negative because the reaction gives off heat.

LorenzoDuvergne3I
Posts: 60
Joined: Fri Sep 28, 2018 12:25 am

Re: Signs for entropy

Postby LorenzoDuvergne3I » Mon Feb 11, 2019 3:33 pm

Is H/T used for every state other than constant pressure? I'm confused about when to use one over the other.

Charles Gu 1D
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

Re: Signs for entropy

Postby Charles Gu 1D » Sat Feb 16, 2019 11:32 am

A positive delta H is for endothermic reactions which will absorb heat and also increase entropy. A negative Delta h is for exothermic reactions which will entropy to decrease since heat is released

harshitasarambale4I
Posts: 58
Joined: Fri Sep 28, 2018 12:26 am

Re: Signs for entropy

Postby harshitasarambale4I » Sat Feb 16, 2019 4:42 pm

How would you determine the signs for enthalpy?


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