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Enthalpy Units

Posted: Sat Jan 26, 2019 5:13 pm
by bonnie_schmitz_1F
What are the units for enthalpy? Sometimes its written in kJ but other times its kJ mol-1. Is there a difference?

Re: Enthalpy Units

Posted: Sat Jan 26, 2019 5:53 pm
by emily gao 1C
enthalpy is in some kind of joules (J, kJ, etc). kJ/mol is just per mole what is the enthalpy
aka its not too significant

Re: Enthalpy Units

Posted: Sat Jan 26, 2019 7:13 pm
by Helen Zhao 1F
Enthalpy is the amount of heat released or absorbed at constant pressure. Whether or not it's kJ or kJ * mol^-1, it doesn't really matter. Just remember to use the units that best fits the question asked.

Re: Enthalpy Units

Posted: Sat Jan 26, 2019 8:50 pm
by Simmi Diwanji 2B
I think enthalpy could be either kJ or kJ/mol but the standard enthalpy of formation always must be kJ/mol.

Re: Enthalpy Units

Posted: Sat Jan 26, 2019 8:55 pm
by maldonadojs
I do not believe that there is a difference, but it follows the information given by the problem.

Re: Enthalpy Units

Posted: Sat Jan 26, 2019 10:29 pm
by Anjali_Kumar1F
What is the standard enthalpy of formation?

Re: Enthalpy Units

Posted: Sat Jan 26, 2019 11:54 pm
by Simran Rai 4E
The standard enthalpy of formation is the enthalpy change when 1 mole of a substance is formed from its element(s). Note that all the substances should be in standard state.

Re: Enthalpy Units

Posted: Sun Jan 27, 2019 3:22 pm
by ran2000
It depends on the situation. When considering a free reaction, we consider kJ since that is the exact amount of energy being released or absorbed. But, when we consider the situation where in we are considering a standard reaction (ex: Haber's process for 1 mol of ammonia), then we write kJ mol-1 to indicate the energy per unit.