Crystallisation RP

Question 1

The crude product was dissolved in the minimum quantity of hot water
and the hot solution was filtered through a hot filter funnel into a conical
flask. This filtration removed any insoluble impurities. The flask was left to
cool to room temperature.
The crystals formed were filtered off using a Buchner funnel and a clean
cork was used to compress the crystals in the funnel. A little cold
water was then poured through the crystals.
After a few minutes, the crystals were removed from the funnel and
weighed.
A small sample was then used to find the melting point.
Give reasons for each of the following practical steps.

Answer 1

No answer just information for rest of flashcards.

Question 2

The minimum quantity of hot water was used

Answer 2

ensure hot solution would be saturated/crystals would form on cooling

Question 3

Flask cooled to room temp before crystals filtered off

Answer 3

yield lower if warm, solubility higher if warm

Question 4

Crystals compressed in the funnel

Answer 4

Air passes through the sample not just round it.

Question 5

A little cold water was poured through the crystals

Answer 5

To remove any soluble impurities