Report sheet of Boiling points and Distillation
Student name:201820018\ ‫كرنك نصرالدين عمر‬
Questions:
1- A pure liquid has a constant boiling point, but a liquid with a constant
boiling point is not necessarily pure. Explain
All pure liquids have a constant boiling point. Some non-pure liquids also have a
constant boiling point. This means that one cannot predict whether or not a liquid is
pure simply by looking at characteristics of boiling points.
2- What is the effect of each of the following on the observed Bp?
a) The thermometer is not kept moist with condensate
b) The presence of volatile impurity
c) presence of low vapor pressure impurity.
d) highly branched structure of the cpd.
3- What effect does an elevation of the external pressure have on the boiling
point?
4- Why is it important that cooling water enters at the lower end & exits at
the upper end of the condenser jacket, and not vice-versa?
Because if water enters from the lowest point, the condenser will always be filled with
cold water to ensure efficient cooling.
The water should always flow into a condenser at its lowest point and exit from its
highest point. This avoids trapping air in the water jacket.
5- during a distillation why should the distilling flask be filled to two thirds
of its capacity only?
If a distilling flask is filled more than two-thirds full, there is a chance of the liquid
boiling (or bumping) over into the condenser or receiving flask without vaporizing. This
would result in an impure distillate. Also, if the flask were too full, there would be too
little surface area for rapid evaporation and therefore the distillation would be very
slow.
You should also consider that a liquid will increase in volume when heated
6- Which procedure was more efficient in separating the mixture which has a
highly Bp components over than 100 c?
(simple distillation) is used for separating mixture with has a boiling point of
more than 80