State Property

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EthanPham_1G
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Joined: Sat Jul 20, 2019 12:17 am

State Property

Postby EthanPham_1G » Sat Jan 25, 2020 4:21 pm

Why is enthalpy (H) a state property but heat (q) is not a state property?

Rory Simpson 2F
Posts: 106
Joined: Fri Aug 09, 2019 12:17 am

Re: State Property

Postby Rory Simpson 2F » Sat Jan 25, 2020 4:28 pm

Heat isn't a state function because the amount of energy transferred as heat depends on how the change in energy occurs. On the other hand, enthalpy is a state function because no matter how the energy change occurs, it only depends on the state of the system.

Vanessa Rojas 4F
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Joined: Wed Feb 20, 2019 12:17 am

Re: State Property

Postby Vanessa Rojas 4F » Sat Jan 25, 2020 5:08 pm

Enthalpy is a state function because when calculating the value it depends on the state the system is currently in. You only take into account the final value minus the initial value. Meaning that the path it took to get from the initial to the final value is not taken into account in the equation. Heat is not a state function because the energy transferred is the amount that goes in or out of a system. In this situation, the path that the energy takes matters. Energy can go in the system (+) or energy can leave the system (-).

Norman Dis4C
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Joined: Sat Sep 28, 2019 12:16 am

Re: State Property

Postby Norman Dis4C » Sun Jan 26, 2020 12:21 pm

Heat is just like work, it is pathway-dependent, so you must take into account how much heat goes in and out of the system. Enthalpy, on the other hand only accounts for the initial and final stage of the reaction.

Matt F
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Joined: Sat Aug 17, 2019 12:17 am

Re: State Property

Postby Matt F » Sun Jan 26, 2020 1:55 pm

Dr. Lavelle gave an example in class with the heating curve for water. The graph showed heat absorbed on the x-axis and temperature on the y-axis. As heat constantly increased, the temperature remained constant and only increased once certain thresholds were reached (melting or boiling points). The temperature is a state property in this case since it only depended on the initial and final state of the system to change. Heat, on the other hand, is not a state property because it was constantly supplied to the system

005384106
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Joined: Sat Aug 24, 2019 12:16 am

Re: State Property

Postby 005384106 » Tue Jan 28, 2020 11:55 am

What is the difference between boiling an melting point?

Oduwole 1E
Posts: 100
Joined: Fri Aug 02, 2019 12:16 am

Re: State Property

Postby Oduwole 1E » Tue Jan 28, 2020 2:03 pm

005384106 wrote:What is the difference between boiling an melting point?


Boiling point is the temperature a substance has to reach in order for it to boil (liquid to gas), and the melting point is the temperature a substance has to reach in order for it to melt (with solid items since they are melting).


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