Fractional Distillation Lab

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Fractional Distillation of a Solution

Results 1. On a single graph, plot boiling point versus volume of distillate curves for the two distillations of the cyclohexane/toluene solutions (one from the simple distillation experiment and one from the fractional distillation experiment). The graph is to be computer generated and presentation quality (e.g., appropriately scaled and labeled axes, descriptive title, and discernable data points). The data points are to be connected with a smooth line.

2. Plot the boiling point versus volume of distillate curve for the distillation of the unknown. Identity of the unknown component responsible for each plateau. 3. Briefly compare and contrast the effectiveness of simple and fractional distillations in the separation of a solution of
cyclohexane and toluene.
The boiling point of a cyclohexane, determined fractional distillation—is very well-defined on this particular distillation, while no boiling point could be really determined in the simple distillation.
The different compounds in a mixture have different boiling points, the two solutions separate into individual components when the mixture is carefully distilled by using fractional distillation.
Problems

1. (a) What is the composition and temperature of the azeotrope?
The composition of the azeotrope is 70% water and 30% formic acid.
(b) What is the boiling point of the mixture when Xformic acid = 0.40?
The boiling point of the mixture when Xformic acid = 0.40 is 105C. (c) What is the composition of the vapor above a boiling solution of Xwater = 0.40?
The composition of the vapor is 15% water and 85% formic acid.
(d) A fractional distillation is carried out for a mixture where Xwater = 0.80. Draw the expected distillation curve, clearly indicating the liquid responsible for the plateaus

2. Justify or refute the following statement: A pure liquid has a constant boiling point but a liquid with a constant boiling point is not necessarily
pure.
True. They are called azeotropes. Azeotropes are mixtures of liquid that can mimic the same boiling behavior as pure liquids, by boiling sometimes lower or sometimes higher than its components 3. Why does a packed fractional distillation column provide more theoretical plates than an unpacked column?
A packed fractional distillation column provide more theoretical plates than an unpacked column because the packed one has more surface per height element where the equilibrium liquid-gas takes place, so the more theoretical plates there is, the more the distillation will be effective.