Page 1 of 1

Standard Reaction Enthalpy

Posted: Fri Jan 12, 2018 2:05 pm
by ClaireHW
HI!
I'm super confused about what a standard reaction enthalpy is. Could someone expand on what Dr. Lavelle defined it as and give another example?
Thanks!

(Claire Woolson Dis. 1K)

Re: Standard Reaction Enthalpy

Posted: Fri Jan 12, 2018 2:06 pm
by ClaireHW
Also what is the difference between Standard reaction enthalpy and standard enthalpy of formation?

(Claire Woolson Dis 1K)

Re: Standard Reaction Enthalpy

Posted: Fri Jan 12, 2018 2:15 pm
by vicenteruelos3
One difference is that standard reaction enthalpy is in KJ, while standard enthalpy of formation is in KJ/mol

Re: Standard Reaction Enthalpy

Posted: Fri Jan 12, 2018 2:21 pm
by Rachel Formaker 1E
Standard reaction enthalpy is specifically the reaction enthalpy for a reaction in which all the products and reactants are in their most stable forms and the pressure is 1 atm.

Reaction enthalpy in general could be for a reaction in which ice is used instead of water, or ozone (O3) instead of O2. Standard reaction enthalpy specifies that all reactants and products are in their most stable forms.

Re: Standard Reaction Enthalpy

Posted: Fri Jan 12, 2018 3:35 pm
by Emma Ward 2C
standard reaction enthalpy occurs within a reaction when the reactants that are in their standards states turn into products in their standard states.

the standard enthalpy of formation is the standard reaction enthalpy PER MOLE of formula units for the formation of a substance from elements in their most stable form.

The standard enthalpy of formation is technically the same thing as standard reaction enthalpy, just per mole of the substance.

Re: Standard Reaction Enthalpy

Posted: Sat Jan 13, 2018 11:18 am
by Susie Lee 2I
When all reactants and products are in their standard state at 1ATM, rxn enthalpy is called standard reaction enthalpy. However, the standard rxn enthalpy for the formation of one mole of a substance from its elements in their most stable form is called standard enthalpy of formation. By definition, the standard enthalpy of formation of an element in its most stable form is zero.

Re: Standard Reaction Enthalpy

Posted: Sat Jan 13, 2018 11:48 am
by Merzia Subhan 1L
For standard enthalpy of formation, I know it is the formation of 1 mole of a substance using its elements in their most stable form, so is it just the pure elements in their standard state, or can it ever be molecules of different elements combined in their standard state?

Re: Standard Reaction Enthalpy

Posted: Sat Jan 13, 2018 2:01 pm
by Yea Eun Lee 1H
As long as the substance is in its most stable form, I'm pretty sure you can use compounds (combination of elements)for the standard enthalpy formation

Re: Standard Reaction Enthalpy

Posted: Sat Jan 13, 2018 2:21 pm
by Timothy Kim 1B
Standard reaction enthalpy is the reaction enthalpy when all R and P are in their standard state at 1 ATM.
Standard enthalpy of formation is the standard reaction enthalpy for the formation of one mole of a substance from its elements in their most stable form.