Question

You are experimenting with an ethanol and water mixture with a mole fraction of ethanol equal to 0.61. See graph.t AHL (k J/mol) A Hwa versus Xethanol 42.5 42.0 41.5 41.0 40.5 y --3.7052 x 42.516 40.0 0.9663 39.5 39.0 0.6 0.8 0.2 0.4 1.0 Mole Fraction of Ethanol Based on the equation above, what is the value of the correct AHvap to use in this experiment? 402 kJ/m You measure the starting pressure and temperature of your system as 1.04 atm and 23.6 C, respectively. What is the pressure of the ethanol-water system at a new temperature of 34.4°C? atm Supporting Materials Constants and Supplemental Data E Periodic Table Factors

Answer 1

a)
delta H vap can calculated from graph and also by formula:
y = -3.7052 x + 42.516
= -3.7052 *0.61 + 42.516
=40.25

Also from graph draw a line and 0.61 and then a horizintal line to get 40.25 KJ/mol

Answer: 40.25 KJ/mol

b)
P1=1.04 atm
T1 = (273 + 23.6) K = 296.6 K
P2= ?
T2 = (273+34.4) K = 307.4 K

use:
P1/T2 = P2/T2
1.04/296.6 = P2/307.4
P2 = 1.08 atm

Answer: 1.08 atm