Purification

Question 1

recrystallisation

Answer 1

choose a solvent in which the solid is insoluble at cold temperature and soluble at hot temp so it will recrystallise on cooling.
dissolve in the minimum amount of hot solvent in order to increase yield.
filter while still hot to remove insoluble impurities and then cool to crystallise.
use vacuum filtration to collect the crystals and remove soluble impurities
wash with ice cold solvent to prevent redissolving
dry

Question 2

purifying an organic liquid

Answer 2

isolate the sample in the separating funnel.
neutralise acid impurities with sodium carbonate and swirl, stops bubbling when neutralised.
open stopper to release pressure and remove the lower aqueous layer.
wash with distilled water so anything more soluble in water goes into solution and is diluted.
run upper organic layer into a conical flask and dry with anhydrous sodium hydrogen carbonate
distil solution

Question 3

explain one factor that influences choice of solvent

Answer 3

solubility, needs to be soluble at high temperatures and insoluble at low temperature so it crystallises out of solution upon cooling

Question 4

order of actions for purifying in a separating funnel

Answer 4

neutralise, wash, separate organic layer, dry, distil

Question 5

explain addition of cyclohexane

Answer 5

acts as a solvent for the organic product formed