Scientific Method: Simple and Fractional Distilation

Question 1

What is the purpose of a distillation?

Answer 1

to separate and purify liquids

Question 2

How does a distillation work?

Answer 2

it exploits the different boiling temperatures of two liquids in a mixture

Question 3

liquid with lower boiling point

Answer 3

volatile

Question 4

apparatus that the evaporated liquid will pass through first where it may be reverted back into a liquid

Answer 4

condensing column

Question 5

Why is it important that cold water is passed through the condenser?

Answer 5

This allows for a gaseous liquid to recondense into its liquid form

Question 6

What is the difference between a simple and fractional distillation set up?

Answer 6

A fractional distillation requires a fractionating column filled with glass beads to be placed between the boiling flask and the condensing column

Question 7

What is the purpose of the glass beads in a fractionating column?

Answer 7

they provide “theoretical plates” on which the refluxing liquid can evaporate and condense on over and over, essentially redistilling the compound again and again.

Question 8

Where do more volatile liquids rest in the fractionating column?

Answer 8

The more volatile liquid will tend to move higher up the column, while the less volatile liquid will remain towards the bottom. This provides a better separation between liquids.

Question 9

When should a simple distillation be used

Answer 9

when the boiling point of two different liquids differ by 40 degrees or more

Question 10

When should a fractional distillation be used?

Answer 10

when the boiling point of two different liquids differ by less than 40 degrees

Question 11

What is the purpose of ethyl acetate (EtOAc) in the distillation experiment?

Answer 11

Ethyl acetate acts as the more volatile compound in the distillation

Question 12

What is the purpose of n-butyl acetate (C6H12O2) in the distillation experiment?

Answer 12

N-Butyl acetate is the less volatile liquid (higher boiling point)

Question 13

Why it important to grease each of the glass joints on the distillation apparatus?

Answer 13

A firm seal helps ensure that no heat or liquid is lost. It also helps ensure safety.

Question 14

What is the purpose of each of the three collection flasks used in the distillation experiment?

Answer 14

• Flask A should house the majority of the distilled ethyl acetate
• Flask B should house the remainder of the distilled ethyl acetate and a small amount of n-butyl acetate when it begins to boil
• Flask C should house purely n-Butyl acetate

Question 15

Why is it important that you do not use full voltage on the transformer?

Answer 15

It will heat the heating mantle too quickly, which will result in a poor separation of liquids

Question 16

Why do we add boiling chips to the distillation pot?

Answer 16

The chips contain pores which allow excess air (bubbles) to be trapped, which allows for the liquids to boil smoothly without boiling over or loosing solution

Question 17

Why is it important to record the temperature versus volume of distillate during the entire distillation?

Answer 17

This is to make sure that the heat and volume reflected at a certain time in the experiment will match up with the expected products in each flask.

Question 18

Why are cork stoppers used instead of rubber stoppers?

Answer 18

Cork stoppers will not expand when under heat and pressure. Rubber will.

Question 19

Why do we cover the fractionating column with aluminum foil in the fractional distillation?

Answer 19

This is to help insulate the column to keep heat in and air draft out.

Question 20

What are the advantages of simple distillation?

Answer 20

• simpler set up than fractional
• faster distillation time
• consumes less energy than fractional distillation

Question 21

What are the advantages of a fractional distillation?

Answer 21

• greater separation between liquids in comparison to simple distillation
• can more readily purify complex mixtures than simple can

Question 22

What are the disadvantages of simple distillation?

Answer 22

• requires large boiling point difference between liquids
• gives poorer separation in comparison to fractional distillation
• only works well with relatively pure liquids

Question 23

What are the disadvantages of fractional distillation?

Answer 23

• more complicated set up
• takes longer for liquids to distill
• consumes more energy than simple

Question 24

What is a simple distillation best used for?

Answer 24

separating relatively pure liquids with large boiling difference or liquids with solid impurities

Question 25

What is a fractional distillation best used for?

Answer 25

separating complex mixtures of liquids with smaller boiling point separations

Question 26

What is A and what is its purpose?

Answer 26

heating mantle - used to slowly heat flask to each liquids respective boiling point

Question 27

What is B and what is its purpose?

Answer 27

distillation flask/pot and boiling chips - used to house and boil liquids. Chips used to absorb bubbles.

Question 28

What is C and what is its purpose?

Answer 28

Thermometer - tells temperature

Question 29

What is D and what is its purpose

Answer 29

condensing column - runs cool liquid through it to recondense vapors

Question 30

What is C and what is its purpose?

Answer 30

fractionating column - longer column used for better separation of vapors

Question 31

What is D and what is its purpose?

Answer 31

glass beads - provides more surface area for vapors to condense and reevaporate on, further distilling the compound(s)

Question 32

Steps of simple distillation

Answer 32

1. set up glassware, making sure to grease glass joints
2. place 2 liquids of equal volume into round bottom flask and attach to distillation apparatus
3. use heating mantle and transformer for heat source
4. place receiving flask A under tip of vacuum adapter and begin heating
5. After every 10 drops, take a temperature reading and record.
6. Switch to receiver B when thermometer hits 81*C and continue recording drops and temp (cork receiver A)
7. Switch to receiver C when temp hits 123*C (cork receiver B)
8. Stop recording when 1-2ml of liquid remains in pot or until plateau becomes clear.

Question 33

what are the safety hazards of this experiment?

Answer 33

• ethyl acetate and n-butyl acetate fumes
• hot mantles
• USE A BOILING CHIP
• secure all the pieces as you build the distillation setup