9: Carboxylic Acids and Esters

Question 1

Describe dissociation of carboxylic acids.

Answer 1

Partially dissociate to H+ and carboxylate ion

Question 2

Carboxylic acid + sodium carbonate produces…

Answer 2

Sodium carboxylate (salt) + water + CO2

Question 3

Name 3 different strong acid catalysts that could be used in esterification reactions.

Answer 3

H2SO4
HCl
H3PO4

Question 3

If you heat a carboxylic acid with alcohol in the presence of a strong acid catalyst, what organic molecule is produced?
What is the name of this reaction?

Answer 3

Ester, formed in esterification.

Question 4

When reversing the reaction of carboxylic acid + alcohol = ester + water, what conditions are needed.

Answer 4

Reflux

Question 5

How do we name esters?

Answer 5

Name the alcohol first, then the carboxylic acid.

Question 6

How do we name benzene rings in esters?

Answer 6

Second in the name, benzoate

Question 7

As esters smell sweet, what can they be used for?

Answer 7

Perfumes, food flavourings

Question 8

Why are esters good solvents?

Answer 8

They are polar so other organic compounds will dissolve in them.

Question 9

Esters can be used as plasticisers - how are they made?

Answer 9

Esters are added to plastics during polymerisation to make the plastic more flexible.

Question 10

What is acid hydrolysis of esters?

Answer 10

Esters are split using a water and a dilute acid to an alcohol and carboxylic acid.

Question 11

What conditions are needed for acid hydrolysis in the forward and backward reaction?

Answer 11

Forward - Dilute acid
Backward - Reflux

Question 12

Give a general equation for acid hydrolysis.

Answer 12

Ester + water = Carboxylic acid + alcohol

Question 13

What conditions are needed for base hydrolysis?

Answer 13

Reflux and dilute alkali

Question 14

What are the products of base hydrolysis?

Answer 14

Carboxylate ion and alcohol

Question 15

What is the IUPAC name of glycerol?

Answer 15

propane-1,2,3-triol

Question 16

Why are saturated fats solid at room temperature?

Answer 16

Saturated fats have no kinks in the chain. This allows the molecules to pack closer together increasing VDW force strength.

Question 17

Why are oils liquids at room temperature?

Answer 17

They contain unsaturated chains, so molecules can’t pack as tightly together and therefore VDW forces are weaker.

Question 18

What type of hydrolysis is used when splitting fats/oils?

Answer 18

Base

Question 19

Base hydrolysis of fats produces what?

Answer 19

Glycerol and sodium salts

Question 20

What are sodium salts used in?

Answer 20

Soaps

Question 21

Give an equation for the conversion of sodium salts CH3(CH2)16COO-Na back into fatty acids CH3(CH2)16COOH

Answer 21

CH3(CH2)16COO-Na + H+ -> CH3(CH2)16COOH + Na+

Question 22

Name the alkali usually used in base hydrolysis of fats.

Answer 22

NaOH

Question 23

What must vegetable oils be reacted with under what conditions to produce biodiesels?

Answer 23

Methanol and strong alkali catalyst

Question 24

What organic compound makes up biodiesels and why?

Answer 24

Methyl esters - because they are formed using methanol

Question 25

Why can biodiesels be thought as carbon neutral?

Answer 25

When crops grow, they absorb the same amount of CO2 as they produce when burnt