1. Using Figure 14.4, answer the following questions. a. What is the molar compo
ID: 783692 • Letter: 1
Question
1. Using Figure 14.4, answer the following questions.
a. What is the molar composition of the vapor in equilibrium with a boiling liquid
that has a composition of 60% A and 40% B?
b. A sample of vapor has the composition 50% A and 50% B. What is the composition
of the boiling liquid that produced this vapor?
2. Use an apparatus similar to that shown in Figure 14.1 and assume that the roundbottom
flask holds 100 mL and the distilling head has an internal volume of 12 mL
in the vertical section. At the end of a distillation, vapor would fill this volume, but
it could not be forced through the system. No liquid would remain in the distillation
flask. Assuming this holdup volume of 112 mL, use the ideal gas law and
assume a boiling point of 100 C (760 mmHg) to calculate the number of milliliters
of liquid (d 0.9 g/mL, MW 200) that would recondense into the distillation
flask upon cooling.
3. Explain the significance of a horizontal line connecting a point on the lower curve
with a point on the upper curve (such as line xy) in Figure 14.4.
Explanation / Answer
1)
from the graph
a)20%A,80% B
b)10% A, 90% B
2)
Figure 14.1 is not given here,
PV=nRt
n = no.of moles = PV/RT = 1*0.112 /0.0821*373 = 3.657*10^-3 moles.
mass of liquid = n*molecular weight = 3.657*10^-3 *200 = 0.731 47gm
volume of liquid = mass/density = 0.73147/0.9 = 0.8127 ml.
3)The significance is , the lower curves refers to the boiling point,
when we keep on increasing the temperature from the bottom and when we reach the lower curve, the liquid starts boiling giving vapours which will be in equilibrium with the liquid, so the horizontal line represents the vapour composition that is in equilibrium with the boiling liquid.
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