Isolation of Essential Oil from a Plant

Question 1

why is a heating mantle used in the first distillation?

Answer 1

provides more heat to boil the water and mixture

Question 2

why is a hot water bath used in the second distillation?

Answer 2

to allow for lower heat due to lower boiling point of dichloromethane

Question 3

what would happen if the temperature got too high during the second distillation?

Answer 3

the oil would decompose and burn

Question 4

give 2 reasons why steam distillation is used in this lab

Answer 4

1. volatile oils can be removed from non-volatile clove components without decomposing organic compounds
2. results in shift in equilibrium that favours the products

Question 5

give 3 reasons why dichloromethane is used to extract oil from water

Answer 5

1. oil is more soluble in it than water
2. it is immiscible with water, so the two can be separated
3. easily recovered

Question 6

what makes dichloromethane easily recovered?

Answer 6

its low boiling point

Question 7

how would trace of water be removed from an organic phase?

Answer 7

drying agent

Question 8

how does a drying agent work?

Answer 8

reacts with water to form solid that can be removed by decanting or filtration

Question 9

a compound with a lower boiling point than another would distill (first/last)?

Answer 9

first. Things distill in order of lowest boiling point

Question 10

why might two components not co-distill?

Answer 10

they are not miscible

Question 11

what is an advantage of using steam distillation?

Answer 11

prevents decomposition of organic solvent and burning oil

Question 12

what is a disadvantage of using steam distillation?

Answer 12

distillate is a mix of all the volatile components, so further separatory actions must happen

Question 13

give 6 reasons why water is used for extraction of oil

Answer 13

1. low molecular weight = big recovery
2. cheap
3. readiliy available
4. non-toxic
5. inert
6. immiscible with oil

Question 14

how do you know that the desired product has stopped distilling in steam distillation? (2 ways)

Answer 14

1. temperature reaches 100 c

2. solution in distilling flask is clear instead of cloudy

Question 15

cloudy solution suggests the presence of what?

Answer 15

oil

Question 16

what are the sources of error for this lab?

Answer 16

1. not enough time
2. loss to drying agent
3. loss to transfers (l-l)
4. incomplete l-l extraction
5. loss during steam distillation

Question 17

why is the %oil in cloves so low?

Answer 17

because oil is only a very small component of the plant

Question 18

why is there incomplete l-l extraction?

Answer 18

b/c of oil’s insolubility in water, more than 2 rinses with dischloromethane will not help