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State Property

Posted: Sat Jan 25, 2020 4:21 pm
by EthanPham_1G
Why is enthalpy (H) a state property but heat (q) is not a state property?

Re: State Property

Posted: Sat Jan 25, 2020 4:28 pm
by Rory Simpson 2F
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.

Re: State Property

Posted: Sat Jan 25, 2020 5:08 pm
by Vanessa Rojas 4F
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 (-).

Re: State Property

Posted: Sun Jan 26, 2020 12:21 pm
by Norman Dis4C
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.

Re: State Property

Posted: Sun Jan 26, 2020 1:55 pm
by Matt F
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

Re: State Property

Posted: Tue Jan 28, 2020 11:55 am
by 005384106
What is the difference between boiling an melting point?

Re: State Property

Posted: Tue Jan 28, 2020 2:03 pm
by Oduwole 1E
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).