Enthalpy

Moderators: Chem_Mod, Chem_Admin

kane_jajieh_3F
Posts: 17
Joined: Wed Sep 21, 2016 2:58 pm

Enthalpy

Postby kane_jajieh_3F » Sat Jan 14, 2017 8:52 pm

In the book it says that enthalpy is a state function. What does this mean? What is a state function?

Lyndon_Bui_3J
Posts: 27
Joined: Sat Jul 09, 2016 3:00 am

Re: Enthalpy

Postby Lyndon_Bui_3J » Sat Jan 14, 2017 9:47 pm

A state function refers to a quantity that can be determined using the final and initial states only. State functions are path independent. Enthalpy is a state function because the delta H or change in enthalpy can be calculated using the final enthalpy and initial enthalpy. This is useful because it allows for us to add enthalpies when "adding" reactions together.

Rosaline_Chow_2L
Posts: 10
Joined: Fri Jul 22, 2016 3:00 am

Re: Enthalpy

Postby Rosaline_Chow_2L » Sat Jan 14, 2017 10:02 pm

Expanding on the answer above, state functions are independent of how the final state of a system is reached. It's easier to understand if you think of an example such as hiking, which was what my TA told us. One hiker could take a winding path from point A to B, while another could make a straight beeline from A to B. In the end, the difference in height between the two points is still the same, regardless of how it took to get there. Furthermore, enthalpy itself is based on state properties such as internal energy, pressure, and volume, as given by the equation H = U + PV.

kane_jajieh_3F
Posts: 17
Joined: Wed Sep 21, 2016 2:58 pm

example 14.9

Postby kane_jajieh_3F » Mon Feb 06, 2017 2:17 pm

in example 14.9 why is the nr value 2 and not one as indicated by the redox equation?

Shelby Slaughter 3D
Posts: 24
Joined: Fri Jul 15, 2016 3:00 am

Re: Enthalpy

Postby Shelby Slaughter 3D » Mon Feb 06, 2017 5:09 pm

For 14.9a Ce goes from having a charge of +8 to +6, therefore n=2 (be careful to notice stoichiometric coefficients!)


Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

Who is online

Users browsing this forum: No registered users and 2 guests