Vapor-liquid equilibrium (VLE) properties versus critical ...
Vapor Liquid Equilibrium Graphs
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Transcript of Vapor Liquid Equilibrium Graphs
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7/28/2019 Vapor Liquid Equilibrium Graphs
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Graphical representation
Figure 2: T-xy diagram for sample 1
Figure 3: xy diagram for sample 1
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0 0.2 0.4 0.6 0.8 1
Temperature,T
X,Y
Liquid
Vapour
Liq Comp
Vap Comp
0
0.1
0.2
0.3
0.4
0.5
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0.8
0.9
1
0 0.2 0.4 0.6 0.8 1
VapComp.y
Liq Comp. x
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Figure 4: T-xy diagram for sample 2
Figure 5: xy diagram for sample 2
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0 0.2 0.4 0.6 0.8 1
Temperature,T
X,Y
Liquid
Vapour
Liq Comp
Vap Comp
0
0.1
0.2
0.3
0.4
0.5
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0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1
VapComp.y
Liq Comp. x
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Figure 6: T- xy diagram for sample 3
Figure 7: xy diagram for sample 3
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0 0.2 0.4 0.6 0.8 1
Temperature,T
X,Y
Liquid
Vapour
Liq Comp
Vap Comp
0
0.1
0.2
0.3
0.4
0.5
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0.9
1
0 0.2 0.4 0.6 0.8 1
VapComp.y
Liq comp. x
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Figure 8: T-xy diagram for sample 4
Figure 9: xy diagram for sample 4
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0 0.2 0.4 0.6 0.8 1
Temperature,T
X,Y
Liquid
Vapour
Liq Comp
Vap Comp
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1
Vapcomp.y
Liq Comp. x
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Figure 10: T-xy diagram for sample 5
Figure 11: xy diagram for sample 5
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0 0.2 0.4 0.6 0.8 1
Temperature,T
X,Y
Liquid
Vapour
Liq Comp
Vap Comp
0
0.1
0.2
0.3
0.4
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1
0 0.2 0.4 0.6 0.8 1
VapComp.y
Liq Comp. x
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Figure 12: Equilibrium temperature-composition diagram of vapor and liquid phase of
ethanol/water system at one atmospheric pressure
At equilibrium temperature of 80oC and atmospheric pressure
Theoretical composition of ethanol
1. vapor phase: yth = 0.642. liquid phase: xth = 0.48
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0 0.2 0.4 0.6 0.8 1
Temperature,T
X,Y
Liquid
Vapour
Tie
line
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DiscussionThe experimental value deviated from theoretical value. Possible reasons for discrepancies
are discussed below:
There might be error while taking refractometer reading as it had to be adjustedmanually which might be inappropriate due to visibility problem. So the mole fraction
determined from the Refractive index vs mole fraction graph was not accurate.
Ethanol is a very volatile substance. While taking the reading of refractive index, aconsiderable portion of the sample was vaporized. This might be the reason of
erroneous reading of the refractometer.
Though the system was assumed to be closed, collection of sample amounts of vaporand liquid might have altered equilibrium compositions at the given temperature.
To satisfy equilibrium relationship, the composition of vapor and liquid phase shouldbe constant at the same time. But the result variation may be due to the collect of both
the sample at slightly different time that gave a varuation in the liquid composition.
