Standard Reaction Enthalpy

Moderators: Chem_Mod, Chem_Admin

ClaireHW
Posts: 60
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

Standard Reaction Enthalpy

Postby ClaireHW » Fri Jan 12, 2018 2:05 pm

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)

ClaireHW
Posts: 60
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

Re: Standard Reaction Enthalpy

Postby ClaireHW » Fri Jan 12, 2018 2:06 pm

Also what is the difference between Standard reaction enthalpy and standard enthalpy of formation?

(Claire Woolson Dis 1K)

vicenteruelos3
Posts: 42
Joined: Fri Sep 29, 2017 7:07 am

Re: Standard Reaction Enthalpy

Postby vicenteruelos3 » Fri Jan 12, 2018 2:15 pm

One difference is that standard reaction enthalpy is in KJ, while standard enthalpy of formation is in KJ/mol

Rachel Formaker 1E
Posts: 86
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 2 times

Re: Standard Reaction Enthalpy

Postby Rachel Formaker 1E » Fri Jan 12, 2018 2:21 pm

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.

Emma Ward 2C
Posts: 32
Joined: Fri Sep 29, 2017 7:05 am

Re: Standard Reaction Enthalpy

Postby Emma Ward 2C » Fri Jan 12, 2018 3:35 pm

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.

Susie Lee 2I
Posts: 20
Joined: Fri Sep 29, 2017 7:05 am

Re: Standard Reaction Enthalpy

Postby Susie Lee 2I » Sat Jan 13, 2018 11:18 am

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.

Merzia Subhan 1L
Posts: 33
Joined: Thu Jul 13, 2017 3:00 am

Re: Standard Reaction Enthalpy

Postby Merzia Subhan 1L » Sat Jan 13, 2018 11:48 am

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?

Yea Eun Lee 1H
Posts: 33
Joined: Fri Sep 29, 2017 7:06 am

Re: Standard Reaction Enthalpy

Postby Yea Eun Lee 1H » Sat Jan 13, 2018 2:01 pm

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

Timothy Kim 1B
Posts: 62
Joined: Fri Sep 29, 2017 7:04 am

Re: Standard Reaction Enthalpy

Postby Timothy Kim 1B » Sat Jan 13, 2018 2:21 pm

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.


Return to “Phase Changes & Related Calculations”

Who is online

Users browsing this forum: No registered users and 1 guest