Enthalpy is a state property

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Matthew Lee 3L
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Enthalpy is a state property

Postby Matthew Lee 3L » Wed Jan 10, 2018 3:26 pm

What does it mean that enthalpy is a state property?

Tatiana Hage 2E
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Re: Enthalpy is a state property

Postby Tatiana Hage 2E » Wed Jan 10, 2018 3:28 pm

Enthalpy is a state function because it depends only on the state of the system and not on the path taken to reach its value.

Alyssa Pelak 1J
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Re: Enthalpy is a state property

Postby Alyssa Pelak 1J » Wed Jan 10, 2018 3:29 pm

This simply means that enthalpy is dependent only on the initial and final values, or the product and reactants. The path taken to obtain that is not important. That explains why we can use the equation delta H= H products-H reactants.

Ryan Sydney Beyer 2B
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Re: Enthalpy is a state property

Postby Ryan Sydney Beyer 2B » Wed Jan 10, 2018 3:32 pm

The definition of a state function i some property whose value doesn't depend on the path taken to get there. Enthalpy is a state function because it only depends on the initial and final conditions, and not the path to establish these conditions. We can also see this from the equation :: ΔH=Hfinal−Hinitial. So we can say that it doesn't really matter, for our purposes here, what goes on in the middle there ... all we care about is what was the beginning and what was the end.

Magdalena Palavecino 1A
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Re: Enthalpy is a state property

Postby Magdalena Palavecino 1A » Wed Jan 10, 2018 7:41 pm

We can also think about state properties in the way Dr Lavelle showed us in class with the mountain image. In class, the path the hikers took to get from point A to B did not matter, which is what the rest was saying about the initial and final points.

Phillip Winters 2F
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Re: Enthalpy is a state property

Postby Phillip Winters 2F » Wed Jan 10, 2018 9:11 pm

Enthalpy being a state property means that the path that it takes to get to the value is not important, unlike work which is not a state property

Masih Tazhibi 2I
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Re: Enthalpy is a state property

Postby Masih Tazhibi 2I » Wed Jan 10, 2018 9:21 pm

It is also important to know that a state property is independent of how the substance was prepared. Good examples of state properties include things like altitude, pressure, volume, temperature. Note that when looking at these values, it isn't important to track the path they have taken; with temperature of water for example, we don't care about how fast, slow, or sporadically the water reached the boiling point of 100 degrees Celsius. What is important is solely the initial and final values.

Michael Cheng 1C
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Re: Enthalpy is a state property

Postby Michael Cheng 1C » Thu Jan 11, 2018 12:22 am

So would Heat be considered a state property or not?

Kyle Sheu 1C
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Re: Enthalpy is a state property

Postby Kyle Sheu 1C » Thu Jan 11, 2018 1:54 am

Heat would not be considered a state property. Heat represents the transfer of energy to or from a system as a result of temp. change.

Even though temperature is a state function, there are many possible paths, for example, that a sample of water can take to go from 10 to 20 degrees C. In one scenario, it can simply be heated 10 degrees. In a second scenario, it can be heated to 100 degrees, vaporized, heated to 500 degrees, cooled, condensed, the cooled down to 20 degrees. (Think of the mountain climbing analogy used in class)

Similarly, work is also not a state function.

Adrian Lim 1G
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Re: Enthalpy is a state property

Postby Adrian Lim 1G » Thu Jan 11, 2018 9:16 am

So would heat be a path function?

Kyle Sheu 1C
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Re: Enthalpy is a state property

Postby Kyle Sheu 1C » Thu Jan 11, 2018 5:27 pm

Yep!

Jasmin Tran 1J
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Re: Enthalpy is a state property

Postby Jasmin Tran 1J » Thu Jan 11, 2018 6:31 pm

Just to add on, heat AND work are both path functions.

Sophie 1I
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Re: Enthalpy is a state property

Postby Sophie 1I » Thu Jan 11, 2018 10:38 pm

Enthalpy is determined by the current state of the system and and is therefore independent of how the state was prepared. It is not reliant on the path of the system.

Guangyu Li 2J
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Re: Enthalpy is a state property

Postby Guangyu Li 2J » Thu Jan 11, 2018 11:54 pm

A State Property is not dependent on path taken to obtain that state but is determined by its state.

E.x. Enthalpy is a state property
Altitude is a state property
WOrk is not a state property


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