RP 10a: Making Aspirin

Question 1

What is the first step to making aspirin called?

Answer 1

Preparation

Question 2

Why should the balance be zeroed before measuring 6g of salicylic acid?

Answer 2

We do not want the mass of the weighing boat included in the mass of the salicylic acid.

Question 3

The 6g of salicylic acid needs to be added to which piece of equipment?
(Give the size).

Answer 3

100cm^3 conical flask

Question 4

How much ethanoic anhydride needs to be measured?
What do we use to measure it?

Answer 4

10cm^3
Measured using a 10cm^3 measuring cylinder.

Question 5

5 drops of which acid need to be added to the conical flask?

Answer 5

Sulfuric acid.

Question 6

Once we have measured the ethanoic anhydride, where do we add it to?

Answer 6

The ethanoic anhydride is then added to the 100cm^3 conical flask containing 6g of salicylic acid.

Question 7

Why do we set up a clamp stand, Bunsen, tripod, gauze etc?

Answer 7

To allow us to create a water bath that we can hold the conical flask solution in.

Question 8

What temperature does the water bath need to be?
What temperature can the water bath not exceed and how do we measure this?

Answer 8

The water bath needs to be at 60C. We measure this using a thermometer.
It must not exceed 65C.

Question 9

After removing the flask from the water bath, why do we leave it to cool?

Answer 9

So it can solidify and seperate.

Question 10

We fill a beaker with how much distilled water?
What do we do with the aspirin?

Answer 10

75cm^3

Question 11

How do we extract the crude aspirin from the mixture?

Answer 11

We pour the solution into the Buchner funnel. The remaining solid caught in the filter paper is the crude aspirin.

Question 12

Describe how to set up the filtration apparatus.
How large does the conical flask need to be?

Answer 12

Put some filter paper in the funnel and place the funnel above a 250cm^3 conical flask.

Question 13

During purification, at what temperature do we then need to prepare a water bath at?
How do we measure the temperature?
What temperature can the water not exceed and why?

Answer 13

75C
We measure temperature using a thermometer.
Water temperature cannot exceed 78C because ethanol will start to boil.

Question 14

Name the 2nd step for making aspirin.

Answer 14

Purification

Question 15

How long should the crude aspirin be left to dry for after filtering?

Answer 15

24 hours.

Question 16

We then transfer the ethanol into what kind of tube?

Answer 16

Boiling tube.

Question 17

How much ethanol do we need to measure using a measuring cylinder?
How large does the measuring cylinder need to be?

Answer 17

15cm^3 using a 25cm^3 measuring cylinder.

Question 18

We then need to D__________ the aspirin in the boiling tube.

Answer 18

Dissolve.

Question 19

A 100cm3 conical flask needs to be filled with how much distilled water?
What 2 other things do we also add to the flask?

Answer 19

We fill a conical flask with 40cm3 of distilled water.
We then add the aspirin solution and the ethanol

Question 20

How do we transfer the crude aspirin from the Buchner funnel to the boiling tube?
What must we not do?

Answer 20

We use a spatula to carefully remove it from the filter paper.
We must not scrape the filter paper as this could transfer the filter paper into the boiling tube.

Question 21

Why do we then leave the flask of ethanol, aspirin and distilled water to cool in an ice bath?

Answer 21

This allows solid aspirin crystals to form.

Question 22

How do we remove the purified aspirin crystals from the conical flask?
What do we record about the crystals once removed from the flask?

Answer 22

We filter the solution using filter paper in a Buchner funnel.
We then weigh their mass.

Question 23

What is the 3rd step for the aspirin practical called?

Answer 23

Finding the melting point

Question 24

Why do we heat the end of a capillary tube using a blue flame in the 3rd stage?
During heating, why do we rotate tube?

Answer 24

To seal the end.
We rotate the tube to ensure the plastic does not bend.

Question 25

What do we do with the capillary tube?

Answer 25

We stick it into a depth of 2mm

Question 26

How do we get the crystals to move to the closed end of the capillary tube?

Answer 26

You could tap the tube against the table to get the crystals to move.

Question 27

What is a thiele tube?

Answer 27

Equipment that can measure the melting point of substances.

Question 28

How can we use a thiele tube to record melting points?
What do they do?

Answer 28

Thiele tubes can melt substances. They have a thermometer attached.
Once the aspirin has melted, immediately record the temperature.