ENGR266 2018 Q A3 (ENGR5003)

ENGR266 2018 Q A3Past paperOld spec ENGR2662:210 marks12 min

ENGR266 Summer 2018 Q A3[PARTIAL] official answers Left out: Parts (c) (5 marks, fugacity of a pure gas from $Z(P)$ via $\ln\phi = \int_0^P (Z-1)\,dP/P$), (d) (2 marks, definition of the excess Gibbs energy) and (e) (8 marks, excess Gibbs energy of benzene/water from modified Raoult's law activity coefficients and Antoine equations) are left out: fugacity, excess Gibbs energy and activity coefficients are not in the current slides or formula sheets (audit tag CHECK).

Answer ALL parts (a) - (e)

Formulas you may need

Phase rule: $P + F = C + 2$ (two-phase binary at fixed $T$ : one degree of freedom, so each $P$ fixes $x_1$ and $y_1$ ) (on the formula sheet)
Reading a P-x-y diagram: bubble point from the bubble (liquid, $x_1$ ) curve, the coexisting vapour from the dew ( $y_1$ ) curve at the same $P$ (tie line) (learn this)

(a)
Plot the following vapour liquid equilibrium data for the acetone(1) / methanol(2) mixture on the graph paper provided and add labels to show the liquid and vapour regions and indicate which lines correspond to the bubble and dew curves.
Pressure /kPa $x_1$ $y_1$
17 0.0 0.0
20 0.22
23 0.21 0.38
27 0.46 0.59
30 0.77 0.81
31 1 1
[6]Third
(b(i))
The acetone(1) / methanol(2) binary mixture contains a mole fraction of acetone of 0.3. (i) What is the mole fraction of acetone in the first bubble that is formed when the pressure crosses the bubble curve.
y_1 (first bubble) =-
[2]
(b(ii))
(ii) What is the mole fraction of acetone in the first droplet that is formed when the pressure crosses the dew curve.
x_1 (first droplet) =-
[2]

Pressure /kPa	$x_1$	$y_1$
17	0.0	0.0
20		0.22
23	0.21	0.38
27	0.46	0.59
30	0.77	0.81
31	1	1