Question

m m Liege Ammerman Campus. Department of Physical Science 2. During a fractional distillation, why is a better separation achieved when heat mation, why is a better separation achieved when heat is applied slowly and steadily? (2 pts) 3. Con Consider heating a pure substance, such as acetone, to its boiling point. Why doesn't all the acetone vaporize instantly when the boiling point is reached? Hint: think about the heat of vaporization. (1 pt) 4. Why is it preferable to allow cold water to enter the bottom of the condenser and exit at the top rather than vice versa? (1 pt) 5. For any pure liquid, what is the relationship between intermolecular forces, vapor pressure, and boiling point? (1.5 pts)

Answer 1

Ans 2 :

Fractional distillation is used to seperate a mixture of liquids that have smaller difference in their boiling points.

The liquid that has lower boiling point boils first and distills out leaving the other liquid behind in the distillation flask.

So heating the mixture slowly and steadily ensures that maximum time is allowed for the liquid to boil and seperate out completely before the other liquid also attains its boiling point and starts to evaporate which may adulterate the first distillate.

This is the reason better separation is achieved when the mixture is heated slowly and steadily.