Lab Exam.

Question 1

What is the structure of salicylic acid?

Answer 1

Question 2

What is the structure of aspirin?

Answer 2

Question 3

What is the reaction for salicylic acid with acetal chloride/pyridine?

Answer 3

Question 4

What is the reaction for aspirin with acetal chloride/pyridine?

Answer 4

Question 5

What is the reaction for salicylic acid with methanol/HCl/heat?

Answer 5

Question 6

What is the reaction for aspirin with methanol/HCl/heat?

Answer 6

Question 7

What is the reaction for salicylic acid with sodium bicarbonate at room temperature?

Answer 7

Question 8

What is the reaction for aspirin with sodium bicarbonate at room temperature?

Answer 8

Question 9

What is the reaction for salicylic acid with thionyl chloride?

Answer 9

Question 10

What is the reaction for aspirin with thionyl chloride?

Answer 10

Question 11

What is the reaction for salicylic acid with 10% sodium hydroxide at room temperature?

Answer 11

Question 12

What is the reaction for aspirin with 10% sodium hydroxide at room temperature?

Answer 12

Question 13

What is the reaction for salicylic acid with excess sodium hydroxide at room temperature?

Answer 13

Question 14

What is the reaction for aspirin with excess sodium hydroxide at room temperature?

Answer 14

Question 15

What is the reaction for salicylic acid with ammonium hydroxide at room temperature?

Answer 15

Question 16

What is the purpose of phosphoric acid in the aspirin lab?

Answer 16

It acts as a catalyst which will quicken the reaction by protonating the carbonyl group on the anhydride.

Question 17

What is the purpose of water in the aspirin lab?

Answer 17

Water removes any excess acetic anhydride.

Question 18

What is the purpose of ice in the aspirin lab?

Answer 18

Ice accelerates crystallisation and increases the yield of the product. It also precipitates the aspirin which is then recrystallised to water.

Question 19

What is the purpose of ethanol in the aspirin lab?

Answer 19

To purify and dissolve the crystals.

Question 20

For the caffeine lab, how do you calculate the percent recovery?

Answer 20

Actual yield * 100% / theoretical yield. Actual yield is the mass of caffeine. Theoretical yield is the mass of caffeine * mass of tea bags.

Question 21

In the caffeine lab, suppose you forgot to add sodium carbonate to the tea solution prior to extraction?

Answer 21

The sodium carbonate acts as a base. When you boil tea, tannins and caffeine dissolve in the water. If a base is not used then the tannins will be extracted into the solvent. The base converts the tannins into sodium salts which are ionic and are not soluble so will remain in the aqueous layer and allow pure caffeine to be extracted.

Question 22

What is the equation for ethanol with Na?

Answer 22

Question 23

What is the equation for ethanol with NaOH?

Answer 23

CH3-CH2-O(-)-Na(+) and H2O

Question 24

What is the equation for ethanol with Na2CO3?

Answer 24

No reaction

Question 25

What is the equation for phenol with Na?

Answer 25

Picture

Question 26

What is the equation for phenol with NaOH?

Answer 26

Picture

Question 27

What is the equation for phenol with Na2CO3?

Answer 27

Picture

Question 28

What is the equation for ethanoic acid with Na?

Answer 28

Picture

Question 29

What is the equation for ethanoic acid with NaOH?

Answer 29

Picture

Question 30

What is the equation for ethanoic acid with Na2CO3?

Answer 30

Picture

Question 31

In the ethyl acetate lab what is the equation for the formation of ethyl acetate?

Answer 31

CH3CH2OH + CH3COOH = CH3COOCH2CH3 + H2O

Question 32

In the ethyl acetate lab, what is the purpose of sulphuric acid?

Answer 32

The sulphuric acid is used because it will catalyse the esterification reaction. It also removes a water molecule from the reaction and is therefore responsible for the dehydration reaction.

Question 33

In the ethyl acetate lab, what happens if water is removed from the reaction mixture?

Answer 33

If water is removed from the reaction, the overall equilibrium of the reaction will shift to the right which will form more products. If more products are formed the system will reach equilibrium.

Question 34

In the ethyl acetate lab, what products are formed when ethanol is oxidised by sodium dichromate?

Answer 34

CH3-COOH

Question 35

What is the reaction for aspirin with ammonium hydroxide at room temperature?

Answer 35