practical for aspirin

Question 1

how can i determine the purity of an organic compound via melting point?

Answer 1

1. pack a small sample of solid into a glass capillary tube, and place inside heating element
2. increase temp until sample turns from solid to liquid
3. measure melting range ( begins to ends )
4. compare measurements to data book value
5. impurities present if melting point is lower and broaden melting range

Question 2

when adding a very hot solvent to the impure solid, why do we use a minimum volume?

Answer 2

• to obtain a saturated solution

Question 3

why do we filter hot solution through heaten funnel?

Answer 3

• to remove any insoluble impurities

Question 4

why do we leave the solution to cool down?

Answer 4

• crystals of the product will form

Question 5

why do we filter the mixture under reduced pressure using a buchner funnel?

Answer 5

• to remove any liquid containing soluble impurities

Question 6

why do we wash the crystals with distilled water?

Answer 6

• to remove any soluble impurities

Question 7

why do we leave the crystals to dry?

Answer 7

• to make sure mass is exact

Question 8

how can volatile liquids be purified by distillation?

Answer 8

1. connect a condenser to a round bottomed flask containing impure solution
2. place thermometer in neck of flask
3. heat impure product ( with electric heater )
4. when product u want to collect boils, place a flask at open end of condenser to collext pure product