Organic Techniques

Question 1

What is refluxing and why do we use it

Answer 1

• refluxing is continuous evaporation and condensation
• it prevents any organic substances being lost by rapid evaporation

Question 2

What is distillation and why do we use it

Answer 2

• distillation separates substances with different boiling points
• gently heating the mixture allows the substances to evaporate out of the mixture in order of increasing boiling point
• the thermometer shows the boiling point of the substance that is evaporating at any given point
• aldehydes have lower boiling point than alcohols so will evaporate and distill out of the reaction mixture as soon as it forms

Question 3

How can we use distillation to separate an impure product

Answer 3

• the pure product will evaporate and condense at it’s boiling point
• collect by placing a flask at the bottom of the condenser

Question 4

How can we use separation

Answer 4

• use separation to remove any impurities in an organic product that do not dissolve in water
• pour product into separating funnel and add water
• organic layer will form above aqueous layer
• open the tap and collect each layer in separate beakers

Question 5

What is an issue with separation

Answer 5

• separation will result in the organic layer containing small amounts of water
• add a drying agent such as calcium chloride which will bind to the water and form solid
• mix solution and filter to remove the solid drying agent

Question 6

How can we determine the purity of an organic product

Answer 6

• distill the product
• read the thermometer at the point of evaporation
• this will tell you the boiling point of your product
• look up in a data booklet the boiling point of the product and compare with your value
• if your product contained impurities, your measures boiling point will be higher than the actual value