Module 4: Synthetic Techniques (Chapter 16)

Question 1

Equpiment needed for reflux

Answer 1

Pear shaped flask 
Condensor
Anti-bumping granules
Stand and clamp
Heat source (water bath or bunsen burner)

Question 2

Purpose of anti-bumping granules

Answer 2

Prevent large bubbles from forming that could be explosive

Question 3

Purpose of reflux

Answer 3

Overcome activation energy
Increase the rate of reaction by reaching the boiling point for a prolonged period of time
Reduce the loss of any reactants and products

Question 4

Benefit of reflux over normal heating

Answer 4

Heating alone would cause some of the product to be lost as vapour (organic substances are very volatile).

Question 5

Should the condensor in reflux be stoppered?

Answer 5

No because it creates a closed system, so pressure builds up, which could cause an explosion

Question 6

Equpiment needed for ditsillation

Answer 6

Pear-shaped flask
Condensor 
Heat source
Stand and clamp
Screw cap adaptor 
Receiver adaptor 
Still head 
Thermometer

Question 7

Purpose of distillation

Answer 7

Separate the pure, desired product from impurities
Separates bby boiling point (lowest first)
Condenser gathers vapour and collection by receiver

Question 8

How do you separate organic products from a mixture with an aqueous solution?

Answer 8

Add water to the mixture to find out the organic layer. The layer that gets larger is the aqueous layer.
Use a separating funnel
Remove the lower layer into a conical flask
Remove the other layer into a different conical flask

Question 9

How can acid impurities be removed when using a separating funnel?

Answer 9

Sodium carbonate (aq) can be added to produce CO2 when the mixture is shaken. Turn the separating funnel upside down (stoppered) and open the tap to relase the gas and reduce pressure. Continue until no more gas is released.

Question 10

How can water impurities be removed from the organic layer?

Answer 10

Addition of an anhydrous drying agent, e.g calcium chloride, calcium sulfate or magnesium sulfate.
Add unitl clumping stops and swirl after each addition.

Question 11

What further process can be done after the use of a separating funnel?

Answer 11

Redistillation to remove any unremoved impurities

Question 12

What indicates a pure product?

Answer 12

Narrow, sharp boiling point. No range

Question 13

Define target molecule

Answer 13

Term used to describe the organic compound that the chemist is trying to prepare