Organic Practicals

Question 1

If a sample is pure, what will the melting point be like?
What if it is impure?

Answer 1

The same as the value in the data books

It would be lowered and the sample will melt over a range of values instead of sharply at one

Question 2

RP10 steps and reasons for each of the 6 steps

Answer 2

steps
1. Dissolve the impure compound in a minimum volume of hot (near boiling) solvent
2. Hot filter solution through (fluted) filter paper quickly
3. Cool the filtered solution by inserting beaker in ice
4. Suction filtrate with a Buchner flask to separate out crystals.
5. Wash the crystals with distilled water.
6. Dry the crystals between absorbent paper

reasons:
1. So the compound is pure in the crystals formed
2. Will remove any insoluble impurities + heat will prevent crystals reforming during filtration
3. Crystals will reform but soluble impurities will remain in solution form
4. Faster filtration bc pressure in flask reduced due to water flow
5. Removes soluble impurities
6. Water affects % yield

Question 3

Why cool the filtered compound slowly in RP10?

Answer 3

So all the compound crystallises, increasing yield

Question 4

Why would you lose yield in RP10?

Answer 4

● Crystals lost when filtering or washing
● Some product stays in solution after recrystallization
● Other side reactions occurring

Question 5

% yield and atom economy formulae

Answer 5

% yield = actual mass of product/theoretical mass of product × 100

% atom economy = Mr of desired product/sum of Mr of all reactants × 100

Question 6

How to heat a flammable reaction mixture

Answer 6

use an electric heater

Question 7

What’s the tube in reflux called?

Answer 7

condenser

Question 8

Give a reason 2 layers form in the separating funnel and why ethyl ethanoate forms the upper layer

Answer 8

Reason: they separate as ethyl ethanoate is less soluble in water and due to differences in density
suggestion: less dense than the lower layer