Acids, esters and polyesters

Question 1

What types of intermolecular forces are present in carboxylic acids?

Answer 1

London forces, permanent dipoles and hydrogen bonds

Question 2

What is the solubility of carboxylic acids in water?

Answer 2

High solubility due to hydrogen bonds

Question 3

What is the name for a salt formed from a carboxylic acid?

Answer 3

Carboxylate

Question 4

What is the test for carboxylic acids?

Answer 4

NaCO3

Effervescence as CO2 is released

Question 5

Carboxylic acid + hydroxide —–>

Answer 5

Carboxylate salt + water

Question 6

Carboxylic acid + metal —–>

Answer 6

Carboxylate salt + hydrogen

Question 7

Carboxylic acid + carbonate —–>

Answer 7

Carboxylate salt + water + carbon dioxide

Question 8

Carboxylic acid + metal oxide —–>

Answer 8

Carboxylate salt + water

Question 9

What is a carboxylic acid derivative?

Answer 9

A compound which can be hydrolysed to return the parent carboxylic acid.

Question 10

What are the three carboxylic acid derivatives?

Answer 10

Acyl chlorides
Acid anhydrides
Esters

Question 11

How is an acyl chloride named?

Answer 11

_____ oyl chloride

Question 12

Give the equation for the formation of an acyl chloride from a carboxylic acid.

Answer 12

Carboxylic acid + SOCl2 ——> Acyl chloride + SO2 + HCl

Question 13

Give the equation for the formation of a carboxylic acid from an acyl chloride.

Answer 13

Acyl chloride + H2O ——> Carboxylic acid + HCl

Question 14

Give 3 methods of preparing esters

Answer 14

alcohol + carboxylic acid
acid anhydride + alcohol
acyl chloride + alcohol

Question 15

Give the equation and conditions for the formation of an ester from an alcohol and carboxylic acid.

Answer 15

alcohol + carboxylic acid ester + water
reversible reaction
heat under reflux
conc sulphuric acid catalyst

Question 16

Give the equation and conditions for the formation of an ester from an alcohol and an acid anhydride.

Answer 16

acid anhydride + alcohol —–> ester + carboxylic acid

RTP

Question 17

Give the equation and conditions for the formation of an ester from an alcohol and an acyl chloride.

Answer 17

acyl chloride + alcohol ——> ester + hydrochloric acid

RTP

Question 18

Define hydrolysis.

Answer 18

A chemical reaction with water that breaks a compound into two compounds, where H+ and OH- are incorporated into the new molecules.

Question 19

Give the equation and conditions for the acid hydrolysis of esters.

Answer 19

ester + water alcohol + carboxylic acid
reversible reaction
dilute sulphuric/ hydrochloric acid catalyst
heat under reflux

Question 20

Give the equation and conditions for the alkaline hydrolysis of esters.

Answer 20

ester + alkali ——–> carboxylate salt + alcohol

RTP

Question 21

Why does alkaline hydrolysis give a better yield than acid hydroysis?

Answer 21

It is a non-reversible reaction, so all of the reactants get converted into products

Question 22

How can a carboxylic acid be restored from its carboxylate salt?

Answer 22

By adding a strong acid which donates protons to the carboxylate salt to produce its conjugate base (the carboxylic acid).

Question 23

Which two functional groups must be present in a monomer to form a polyester?

Answer 23

alcohol

carboxylic acid

Question 24

Which two combinations of monomers allow polyesters to form?

Answer 24

A hydroxy carboxylic acid
OR
A diol with a dicarboxylic acid

Question 25

What is a polyseter?

Answer 25

A condensation polymer joined by ester links, which release water molecules when formed.