16.1 practical techniques in organic chemistry

Question 1

what are the basic set of quickfit apparatus?

Answer 1

1. round- bottom or pear- shaped flask
2. receiver
3. condenser
4. screw- tap adaptor
5. still head

Question 2

what apparatus is needed to heat under reflux?

Answer 2

1. round- bottom or pear- shaped flask
2. condenser
3. rubber tubing
4. stand and clamp
5. Bunsen burner
6. tripod
7. gauze

Question 3

what apparatus is needed for distillation?

Answer 3

1. round- bottom or pear- shaped flask
2. condenser
3. rubber tubing
4. clamp and stand
5. Bunsen burner
6. tripod
7. gauze
8. screw- cap adaptor
9. receiver adaptor
10. still head
11. thermometer

Question 4

how do you identify the organic layer?

Answer 4

• add water

- the layer that gets bigger is the aqueous layer

Question 5

how do you remove the organic layer from the aqueous layer?

Answer 5

1. pout the mixture of liquids into the separating funnel, place a stopper in the top of the separating funnel, and invert to mix the contents
2. allow the layers to settle
3. add some water to see which layer increases in volume- aqueous layer
4. place a conical flask under the separating funnel, remove the stopper and open the tap until the whole of the lower layer has left the funnel
5. place a second conical flask under the separating funnel to collect the other layer

Question 6

what is anhydrous calcium chloride used for?

Answer 6

drying hydrocarbons

Question 7

what is anhydrous calcium sulphate used for?

Answer 7

general drying

Question 8

what is anhydrous magnesium sulphate used for?

Answer 8

general drying

Question 9

what is the procedure for drying an organic liquid?

Answer 9

1. add the organic liquid to a conical flask
2. add drying agent to the liquid and gently swirl the contents to mix together
3. place a stopper on the flask to prevent your product from evaporating away
4. leave for 10 minutes
5. decant the liquid from the solid into another flask. if the liquid is dry it should be clear

Question 10

outline the steps that you would need to carry out to separate the organic liquid 1-bromobutane from a mixture of 1-bromobutane, water and sulphuric acid

Answer 10

• add aqueous sodium carbonate and shaking the mixture in the separating funnel
• any acid present will react with sodium carbonate releasing CO2(g)
• open tap slowly, holding the separating funnel upside down, to release any gas pressure that may build up
• aqueous sodium carbonate layer and organic layer are run off and the organic layer washed with water before running both layers off into 2 separate flasks