Organic Chemistry 4.29C-4.50C

Question 1

4.29C What is the functional group of alcohols

Answer 1

-OH attached to a hydrocarbon chain

Question 2

What is the general formula of alcohols

Answer 2

CnH2n+2O

Question 3

4. 31C How can ethanol be oxidised by:
   a) burning in air or oxygen
   b) microbial oxidisation
   c) potassium dichromate (IV) in dilute sulphuric acid

Answer 3

a) Complete combustion of ethanol
C2H6O + 3O2 -> 2CO2 + 3H2O

b) Ethanol reacts with oxygen in the air to form ethanoic acid with microbes as catalysts (enzymes)
C2H6O + O2 -> C2H4O2 + H2O

c) oxidised with potassium dichromate (IV) in dilute sulphuric acid to form carboxylic acids

Question 4

4.32C How can ethanol be manufactured by hydration

Answer 4

Reacting ethene with steam known as hydration
C2H4 + H2O -> C2H6O (addition reaction)
1 volume of ethene + 0.6 volumes of steam -> 300C, 60-70atm, phosphoric (V) acid catalyst -> gases are cooled and ethanol turns to liquid and unreacted gases recycled

Question 5

4.32C How can ethanol be manufactured by fermentation

Answer 5

C6H12O6 -> 2C2H6O + 2CO2
glucose -> ethanol + carbon dioxide

Glucose from sugar cane in the absence of air at an optimum temperature of about 30C and using the enzymes in yeast, aerobic respiration would occur in presence of oxygen produced water and carbon dioxide

Question 6

4.34C what is the carboxylic acids functional group

Answer 6

-COOH

Question 7

4.36C What do solutions of carboxylic acids react with metals

Answer 7

Forms salts
ethanoic acid + magnesium -> magnesium ethanoate + hydrogen
2CH3COOH + Mg -> (CH3COO)2Mg + H2
ethanoic acid + sodium carbonate -> sodium ethanoate + carbon dioxide + water

Question 8

4.37C What is vinger

Answer 8

An aqueous containing ethanoic acid

Question 9

4.38C What are the esters functional group

Answer 9

-COO-

Question 10

4.44 What is an addition polymer

Answer 10

A large molecule made from small molecules called monomers

Question 11

How are esters made and what type of reaction is this

Answer 11

A reaction of alcohols with carboxylic acids

Condensation reaction - two molecules react together to make a larger molecule + water

Question 12

4.39C What is produced when ethanol and ethanoic acid react in the presence of an acid catalyst

Answer 12

Ethyl ethanoate ester and water

In displayed formula remove O-H and H then combine and is normally flipped around

Question 13

4.41C How do you find out the name of an ester from the alcohol and carboxylic acid

Answer 13

The double bond part is the acid and the number of carbon atoms in a row decipher the ester

Question 14

4.40C What is the structural formula of ethyl ethanoate

Answer 14

CH3COOCH2CH3

Question 15

4.42C What are esters used for and properties

Answer 15

Uses:

• Perfume
• Food flavourings

Properties

• Distinctive smell
• Volatile

Question 16

4.43C Describe a practical to prepare a sample of an ester such as ethyl ethanoate

Answer 16

• Put one drop of conc sulfuric acid into a test tube
• Add 10 drops of ethanol to the test tube
• Add 10 drops of conc ethanoic acid to the test tube
• Cover the top with cling film
• Place the test tube into a beaker containing 100cm3 hot water u the kettle at approximately 60-80C and leave for 5-10 mins
• Remove and pour contents into a beaker with 25cm3 sodium carbonate solution and carefully smell the ester (distinctive)

Question 17

4.47 What are some problems in the disposal of addition polymers

Answer 17

• Non-biodegradable (not broken down by microorganisms in the environment) so cannot be easily disposed of - land fill
• Produce toxic gases when they are burned - incineration

Question 18

4.48C What happens in condensation polymerisation

Answer 18

A dicarboxylic acid reacts with a diol, produces a polyester and water
Monomers join together with loss of water

Question 19

4.50C What are characteristics of some polymers

Answer 19

Biopolyesters are biodegradable