4.2

Question 1

Alcohol General formula and facts.

Answer 1

• General formula is Cn H2n+1 OH

* Can be primary, secondary and Tertiary

Question 2

What bond can the Hydroxyl group form?

Answer 2

• Hydrogen bonds

* due to electronegativity which gives the hydrogen a positive charge.

Question 3

Trend of solubility.

Answer 3

As Alcohols increase in size, the solubility decreases.

due to the fact that in larger alcohols most of the molecule is non polar so there is less attraction for the polar H2O molecules.

Question 4

How to turn an alcohol into a haloalkane.

Answer 4

The Hydroxyl group (-OH) group is replaced by a halide.

This is a substitution reaction and happens with a halide ion like NaBr.

This requires an acid catalyst like H2SO4.

Question 5

Alcohols to Alkenes

Answer 5

Dehydration.

• An elimination reaction where you eliminate the water from Alcohols.
• The alcohol needs to be mixed with an acid catalyst ( conc sulfuric acid) or (conc Phosphoric acid) and then heated
• E/Z isomers can form.

Question 6

Simple way to oxidise alcohols.

Answer 6

• You can burn Alcohols so the C-C and C-H bonds are broken and the alcohol is completely oxidised to make carbon dioxide and water.
• This is complete combustion.
• Plenty of oxygen needed.

Question 7

Primary Alcohols Oxidation facts.

Answer 7

• They can be oxidised twice first to form Aldehydes which can then form Carboxylic acids.
• It needs to have an oxidising agent like (potassium dichromate (VI))

Question 8

Secondary Alcohols Oxidation facts.

Answer 8

• Refluxing a secondary alcohol with acidified dichromate (VI) will produce a Ketone.
• Ketones can’t be oxidised easily so prolonged refluxing won’t produce anymore.

Question 9

Tertiary Alcohols Oxidation facts.

Answer 9

• They don’t react with potassium dichromate(VI) at all.

* The only way to oxidise them is by burning them.

Question 10

Why can the carbon halogen bond be attacked by a nucleophile.

Answer 10

• Halogens are more electronegative than carbon so the carbon-halogen bond is polar.
• The s+ Carbon is electron deficient so can be attacked by a nucleophile.

OH-, CN- and CH3 are nucleophiles

Question 11

Haloalkanes to Alcohols

Answer 11

• They can be Hydrolysed
• Nucleophilic Substitution reaction
• Hydrolysis is when water breaks bonds.

Question 12

Nucleophilic Substitution Reaction with OH- and Br

Answer 12

• OH- is the nucleophile which gives a pair of electrons for the C+
• The C-Br bond breaks heterolytically (both electrons from the bond are taken by the Br-
• Br- falls off.

Question 13

Why are Idoalkanes hydrolysed the fastest?

Answer 13

*Iodoalkanes have the weakest carbon- halogen bonds so they hydrolyse the fastest

Question 14

what are CFCs?

Answer 14

a class of organic compounds with Chlorine atoms and fluorine atoms.

Question 15

What are CFCs used for and why?

Answer 15

They don’t react with other substances and are non toxic. This means they are used in fire safety equipment and being used as refrigerants.

Question 16

What is Ozone and why does it help us?

Answer 16

It’s a later of O3 molecules and protects us from harmful uv radiation from the sun and stabilises temperatures.

It absorbs the radiation which can lead to cell mutations that can cause skin cancer.

Question 17

What is the bad thing about Ozone.

Answer 17

It’s toxic to humans and contributes to smog.

Question 18

How is Ozone under attack?

Answer 18

The chlorine free radicals formed from CFCs can catalyse the decomposition of ozone to make diatomic oxygen.