Excess Enthalpy and Heat Capacity for an Ethanol-Water Mixture
Excess Enthalpy and Heat Capacity for an Ethanol-Water Mixture
Consider a binary mixture of ethanol and water. Expressions for the excess enthalpy (in J/mol) and heat capacity (in J/mol·K) have been determined for this binary liquid system for the temperature range 298.15 K to 383.15 K by fitting experimental data to an empirical equation [1].
This equation for the excess enthalpy is =x(1-x)(T)+(T)+(T)+(T)+(T), where is the temperature and is the ethanol mole fraction. The excess heat capacity is given by ==x(1-x)++++. Finally, (T)=+T+, where and , , and are appropriate constants tabulated in [1].
E
H
a
0
a
0.5
0.5
x
a
1.5
1.5
x
a
2.5
2.5
x
a
4.5
4.5
x
T
x
E
C
P
∂
E
H
∂T
P
d(T)
a
0
dT
d(T)
a
0.5
dT
0.5
x
d(T)
a
1.5
dT
1.5
x
d(T)
a
2.5
dT
2.5
x
d(T)
a
4.5
dT
4.5
x
a
m
b
m
c
m
d
m
2
T
m=0,0.5,1.5,2.5,4.5
b
m
c
m
d
m
This Demonstration plots both excess properties versus ethanol mole fraction for user-selected values of temperature.