Changing the energy of a system

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KaitlynWatkins2D
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Joined: Fri Sep 25, 2015 3:00 am

Changing the energy of a system

Postby KaitlynWatkins2D » Sun Jan 17, 2016 8:39 pm

In the course reader is says the three ways of changing the energy of a system is to add or remove the amount of substance in the system, heat or cool the system, or do work on the system. It also says that the first way is for open systems and the second two ways are for closed systems. My question is, do the ways that change closed systems also change open systems?

Alex 3F
Posts: 27
Joined: Fri Sep 25, 2015 3:00 am

Re: Changing the energy of a system

Postby Alex 3F » Sun Jan 17, 2016 8:40 pm

No, because in a closed system you cannot add or remove substances since the only thing that is exchanged is energy.

jbcarton
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Joined: Fri Sep 25, 2015 3:00 am

Re: Changing the energy of a system

Postby jbcarton » Wed Jan 20, 2016 2:05 am

I think the first response read the question wrong, I believe the answer is yes. The ways that you can change the energy for a closed system (Heating/cooling and doing work on the system) can be used on an open system as well, HOWEVER the way that the course reader says to change an open system (adding/removing substance) cannot be used on a closed system, as the closed system does not allow for the exchange of matter. I believe the course reader brushes over this a little higher on that page (pg 23) when it compares the different kinds of systems:

Open system: Both matter (adding/removing substances) and energy (heating/cooling or doing work) can exchange
Closed system: Only energy (heating/cooling or doing work) can exchange

jbcarton
Posts: 11
Joined: Fri Sep 25, 2015 3:00 am

Re: Changing the energy of a system

Postby jbcarton » Wed Jan 20, 2016 2:08 am

In simpler terms, the energy in open systems can be changed by all ways (adding/removing substance, heating/cooling, and doing work) while closed systems can only do the last two ways (heating/cooling and doing work). Hope this helps!

Chem_Mod
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Re: Changing the energy of a system

Postby Chem_Mod » Wed Jan 20, 2016 9:35 am

Good discussion! The above answers are correct. For open system, you can add/remove matters but not in closed system. You can heat/cool both system. You can't do anything with isolated system.


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