State Properties

Moderators: Chem_Mod, Chem_Admin

Raquel Rodriguez
Posts: 68
Joined: Fri Sep 28, 2018 12:26 am

State Properties

Postby Raquel Rodriguez » Thu Jan 24, 2019 2:48 pm

Why isn't heat and work not a state property?

Sophia_Kiessling_2L
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am

Re: State Properties

Postby Sophia_Kiessling_2L » Thu Jan 24, 2019 3:05 pm

Because calculating those units requires you to look at the path that was taken to get to that state; not just the final state of the system.

Cynthia Aragon 1B
Posts: 47
Joined: Mon Apr 09, 2018 1:38 pm

Re: State Properties

Postby Cynthia Aragon 1B » Thu Jan 24, 2019 3:27 pm

One way to think why heat and work is using this analogy. Suppose that you and your friend are trying to reach a mountain elevation of 1100 m and are at the same initial starting point, lets say at 150 m elevation. You may decide to walk it while your friend opts to take a bus. Then you both compare how much energy was spent using your particular method of travel. One will notice that the person who walked spent way more energy. There are two levels of work presented in this case but it all depends on the path you take to get to the final state in this case the mountain.

Riley Dean 2D
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Re: State Properties

Postby Riley Dean 2D » Fri Jan 25, 2019 10:49 pm

Their value cannot be determined based solely on their current state, the path taken must be considered, whereas something like enthalpy can be determined on its current state

taryn_baldus2E
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

Re: State Properties

Postby taryn_baldus2E » Sat Jan 26, 2019 9:17 am

State functions simply observe your conditions at that current moment, but in the case of work and heat, the efficiency of each reaction or how it is carried out can determine its value, meaning that you must take into account the entire pathway.

melodyzaki2E
Posts: 61
Joined: Fri Sep 28, 2018 12:18 am

Re: State Properties

Postby melodyzaki2E » Sat Jan 26, 2019 10:35 am

work can't be a state function because it is proportional to the distance an object is moved, which depends on the path used to go from the initial to the final state and thus if work isn't a state function, then heat can't be a state function either because according to the first law of thermodynamics, the change in the internal energy of a system is equal to the sum of the heat and the work transferred between the system and its surroundings.

Aleeque Marselian 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

Re: State Properties

Postby Aleeque Marselian 1A » Sat Jan 26, 2019 11:57 am

Heat and work aren't state properties because you would need to evaluate the path taken in order to determine its value, whereas with state functions only the final and initial values are needed.


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 1 guest