State Property/Function

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Kathleen Nguyen 3G
Posts: 23
Joined: Wed Sep 21, 2016 2:58 pm

State Property/Function

Postby Kathleen Nguyen 3G » Thu Jan 12, 2017 8:30 pm

What is being referred to as "state"? Is it the (physical) state of a substance? And I understand that a "state function" is "a property whose value does not depend on the path taken to get that specific value", but what does that mean exactly? Examples please!

Christopher Liu 3J
Posts: 20
Joined: Fri Jul 15, 2016 3:00 am

Re: State Property/Function

Postby Christopher Liu 3J » Thu Jan 12, 2017 9:39 pm

State functions being path independent means that value will be the same regardless of how you got to that specific value. An example would be enthalpy or qp. Remember that enthalpy is the amount of heat released/absorbed at a constant pressure. If I want to melt 1 gram of ice that initially is at 0 degrees C, it would take 333.55 Joules (I just looked up the value). That means I want qp=333.55 Joules. I could just transfer 333.55 Joules directly to the ice and that would satisfy the requirement or I could maybe lower the temperature of the ice to -10 Celsius and then proceed to melt the ice. Even in the second option, qp would be 333.55 Joules. That means that enthalpy must be path dependent because any route I take results in the same answer.

As to what state refers to, I'm not too sure. Sorry!

stephanieyang_3F
Posts: 62
Joined: Wed Sep 21, 2016 2:55 pm

Re: State Property/Function

Postby stephanieyang_3F » Thu Jan 12, 2017 9:45 pm

I think "state" depends on the type of state function you're dealing with. An example would be something like a change in volume and the initial volume or "state" would be something like 30 mL to its final volume or "state" as 100 mL. I don't think "state" is referring to "physical states of a substance" if what you mean is like ice, water, and steam. I think it's just to refer to initial/final values of whatever state function you're referring to. Hope I answered your question!

Christopher Liu 3J
Posts: 20
Joined: Fri Jul 15, 2016 3:00 am

Re: State Property/Function

Postby Christopher Liu 3J » Thu Jan 12, 2017 9:57 pm

Yup, what Stephanie said sounds right considering state properties only take into account the initial and final values.


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