Question

At triple point, vapor pressure of ice is given by ln p* = 18 – 2560/T, and vapor pressure of water is given by ln p* = 28 – 5120/T, what is the temperature at triple point?

(a) 225 K

(b) 256 K

(c) 320 K

(d) 400 K

I got this question in an interview for internship.

The above asked question is from Modeling and Predicting Vapor Pressure in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering

Answer 1

Correct choice is (b) 256 K

Easy explanation: At triple point pressure and temperature of all the phases becomes same, => 18 – 2560/T = 28 – 5120/T, => 10 = 2560/T, => T = 256 K.