It turns out that the vapor pressure has a special dependence on the temperature

Question

It turns out that the vapor pressure has a special dependence on the temperature, namely through an equation called the Clausius-Clapeyron equation: ????????=????^?????????/????

where A is called the pre-exponential term, Eact is called the activation energy, T is the absolute temperature, and R is the gas constant. If you take the natural log of both sides of this equation, you will get:

????(????????)=?????????/????+??

where ??=ln(??). For this problem, your goal is to determine the value of Eact for water using the data in the saturated steam tables in the back of your book. Specifically, notice that from the second equation above, the plot of ln (Pvap) (y) versus (1/T) (x) should be a line with a slope of (-Eact/RT).

Therefore, for the temperature range of 200

Explanation / Answer

Image not clearly visible, but I tried my best.

Pvap for 200 C = 1941 KJ

Pvap for 300 C = 1405 KJ

ln(Pvap1/Pvap2) = -Ea/R [1/T2 - 1/T1]

ln(1941/1405) = -Ea/R [1/573 - 1/473]

So slope = -Ea/R = -875.87

So Activation Energy = Ea = 875.87*8.314 = 7282 J = 7.282 KJ

Pvap = A*e^(-Ea/RT)

At T = 473 K, Pvap = 1941 KJ

1941 = A*e^(-875.87/473)

So Pre-exponential term = A = 12365.83 KJ

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.