Phase Change
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Re: Phase Change
The information should be given, possibly in a phase change graph. I believe it would be the difference in y-value between two of the horizontal lines (the height of the diagonal) as this would be the energy into the system to bring the substance from one state up to the next.
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Re: Phase Change
KDang_1D wrote:The information should be given, possibly in a phase change graph. I believe it would be the difference in y-value between two of the horizontal lines (the height of the diagonal) as this would be the energy into the system to bring the substance from one state up to the next.
Yes, it should be given, either as a phase change graph or as stated values. Stated values will look like delta H (fus) = some number, and that means that the number they give is the phase change enthalpy from solid <--> liquid. delta H (vap) refers to liquid <--> gas.
Also, I think the phase change enthalpy on a graph is actually the horizontal line; the diagonal line happens when temperature is rising and the horizontal line happens when heat is being used not to raise temperature, but to change phases
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Re: Phase Change
Those values should be given to you (I.e. the heat of vaporization of water is 40.7 kJ/mol), but it is up to you to multiply those values accordingly depending on how much of something you have (I.e. moles of water).
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Re: Phase Change
I also think it would be possible that we would have to calculate the phase change enthalpy for sublimation based on given values of vaporization and fusion.
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