Enthalpy as a state function

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Lara Kristine Bacasen 1L
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Enthalpy as a state function

Postby Lara Kristine Bacasen 1L » Sat Jan 25, 2020 10:35 pm

Can someone explain the statement "Enthalpy is a state function and therefore must be additive"? It was in lecture.

Suraj Doshi 2G
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Re: Enthalpy as a state function

Postby Suraj Doshi 2G » Sat Jan 25, 2020 10:43 pm

A state property means that the value of the variable (in this case enthalpy) is determined by the current state of the substance.

Since enthalpy can change, it is referred to as a state function because we must take into account the addition and subtraction that is associated with the calculations when calculating the final enthalpy.

Alex Chen 2L
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Re: Enthalpy as a state function

Postby Alex Chen 2L » Sat Jan 25, 2020 11:43 pm

A state function is only determined by the current equilibrium of reactants and products, not the path it took to get there. For example, change in Enthalpy is a state function because you only take into account the final state minus the initial state. We can therefore add enthalpy changes when combining reactions because we only have to take in account the final state of the overall reaction.

faithkim1L
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Joined: Fri Aug 09, 2019 12:17 am

Re: Enthalpy as a state function

Postby faithkim1L » Sat Jan 25, 2020 11:46 pm

A state function is determined by the current equilibrium of the reactants and products, meaning that the path taken to reach that current state does not matter. Basically, it means final - initial is a valid calculation for enthalpy.

Matt F
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Re: Enthalpy as a state function

Postby Matt F » Sun Jan 26, 2020 2:02 pm

If you remember in lecture Dr. Lavelle gave the example of the hikers climbing up a mountain. They both took different paths but still ended up on the same point on the mountain. Distance traveled, or work in this case, would not be a state property since it differed depending on the path taken. Altitude, however, would be a state property because both hikers ended up at the same level despite how they got there. Enthalpy and other state properties are similar to altitude in that it doesn't matter how you got there, only the initial and final states. That's why it can be added or subtracted


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