Estimate the heat of vaporization of ethanol at 65 degree C

Estimate the heat of vaporization of ethanol at 65 degree C using the Clapeyron Equation. Given: dp^/dT = delta H^vap/T delta V^vap (Clapeyron Equation) delta V^vap = 1.026 m^3/kg Determine the vapor pressure of ethanol using the Antoine Equation. Determine the slope of the vapor pressure curve at the temperature of interest. Determine delta H^vap.

Solution

Antoine constnat of ethanol are

We know,

ln(P) = A- (B/T+C)

= 4.92365 - ( 1410.46 / ( 65+ 208.514))

P = 0.792 bar

Slope = dP/dT = delta H /T x deltaV = delta H / 346.78 = 586 kJ/kg / 346.78 == 1689.9

At 1 atm pressure, the temperature is boling point of ethanol = 78.4 ^oC

So from the reaction,

dP/dT = delta H/T delta V

P2-P1 = delta H/ delta V x ln(T2/T1)

1.013x10⁵ - 0.792x10⁵ = delta H /1.026 ln( 351.49 / 338.15)

delta H = 586.0 kJ/kg

A = 4.92365

B= 1410.46

C = 208.514