carboxylic acids

Question 1

explain how ethanoic acid dissociates in water

Answer 1

• C=O attracts electrons away from the O-H
• O-H bond polarised and weakens so breaks easily to release H⁺

Question 2

explain why chloroethanoic acid is more acidic than ethanoic acid

Answer 2

• Cl more electronegative so has a negative inductive effect
• O-H bond more polarised and weakens
• more H⁺ released

Question 3

equation for reaction of methanoic acid with sodium carbonate

Answer 3

2HCOOH + Na₂CO₃ → 2HCOONa + CO₂ + H₂O

Question 4

test and observation for carboxylic acids

Answer 4

• sodium carbonate
• effervescence

Question 5

name of reaction between carboxylic acid and alcohol, condition and observation

Answer 5

reaction: esterification
condition: conc. sulfuric acid
observation: sweet smell (ester)

Question 6

equation for reaction of ethanoic acid and methanol

Answer 6

CH₃COOH + CH₃OH ⇌ CH₃COOCH₃ + H₂O

Question 7

name of reaction between ester and water and reagent

Answer 7

reaction: acid hydrolysis
condition: water and conc. sulfuric acid

Question 8

equation for acid hydrolysis of CH₃COOCH₃

Answer 8

CH₃COOCH₃ + H₂O ⇌ CH₃COOH + CH₃OH

Question 9

name of reaction between ester and NaOH

Answer 9

base hydrolysis

Question 10

equation for both steps of base hydrolysis of ethyl methanoate

Answer 10

step 1: HCOOCH₂CH₃ + NaOH → HCOONa + CH₃CH₂OH
step 2: HCOONa + HCl → HCOOH + NaCl

Question 11

IUPAC name for glycerol

Answer 11

propane-1,2,3-triol

Question 12

general equation for basic hydrolysis of triesters/fats to make soap

Answer 12

triester + NaOH → propane-1,2,3-triol + mixture of sodium carboxylate salts

Question 13

use of carboxylate salts

Answer 13

manufacture of soap

Question 14

complete equation:

Answer 14

Question 15

define biofuel

Answer 15

fuel produced from renewable biological sources

Question 16

general equation for hydrolysis of triester to biofuel

Answer 16

triester + methanol → propane-1,2,3-triol + mixture of methyl esters

Question 17

complete equation:

Answer 17

Question 18

side product for reactions of acyl chlorides

Answer 18

HCl

Question 19

acyl chloride + water= ?

Answer 19

carboxylic acid

Question 20

acyl chloride + alcohol= ?

Answer 20

ester

Question 21

acyl chloride + ammonia= ?

Answer 21

amide

Question 22

acyl chloride + amine= ?

Answer 22

N-substituted amide

Question 23

equation for reaction of ethanoyl chloride with water
and name organic product

Answer 23

CH₃COCl + H₂O → CH₃COOH + HCl

product: ethanoic acid

Question 24

equation for reaction of methanoyl chloride with ethanol
and name organic product

Answer 24

HCOCl + CH₃CH₂OH → HCOOCH₂CH₃ + HCl

product: ethylmethanoate

Question 25

why are acyl chlorides preferred over carboxylic acids for formation of esters

Answer 25

- higher yield as reaction not reversible - no sulfuric acid catalyst required - purer product

Question 26

equation for reaction of ethanoyl chloride with ammonia and name organic product

Answer 26

CH₃COCl + NH₃ → CH₃CONH₂ + HCl product: ethanamide

Question 27

equation for reaction between butanoyl chloride and ethylamine and name organic product

Answer 27

CH₃CH₂CH₂COCl + CH₃CH₂NH₂ → CH₃CH₂CH₂CONHCH₂CH₃ + HCl product: N-ethylbutanamide

Question 28

why are acid anhydrides preferred over acyl chlorides in formation of esters

Answer 28

- no corrosive HCl formed - acid anhydrides less vulnerable to hydrolysis

Question 29

how are acid anhydrides formed

Answer 29

two carboxylic acids join together with elimination of water molecule

Question 30

name:

Answer 30

ethanoic propanoic anhydride

Question 31

side product for reactions of acid anhydrides

Answer 31

carboxylic acid

Question 32

equation for reaction of ethanoic anhydride and water

Answer 32

Question 33

equation for reaction of propanoic anhydride and methanol

Answer 33

Question 34

equation for reaction of ethanoic anhydride and ammonia

Answer 34

Question 35

equation for reaction of ethanoic anhydride and propylamine