-OH

Question 1

What are alcohols?

Answer 1

Alcohols are part of the homologous series (-OH).

THEY ARE SATURATED ORGANIC MOLECULES as they contain only single carbon to carbon bonds.

They have a general formula of CnH2n+1OH .

They have a gradation in their physical properties (their boiling points and melting points increase as the chains get larger)

Question 2

What is the boiling point in degrees Celsius of alcohols from methanol to pentanol?

Answer 2

Methanol: 65
Ethanol:    79
Propanol: 97
Butanol:   117
Pentanol:  138

Question 3

What are primary alcohols?

Answer 3

When the -OH group is attached to a carbon with no more than 1 alkyl group

Question 4

What are secondary alcohols?

Answer 4

When the -OH group is attached to a carbon with no more than 2 alkyl groups

Question 5

What are tertiary alcohols?

Answer 5

When the -OH group is attached to a carbon with no more than 3 alkyl groups

Question 6

What are the trends with alcohols?

Answer 6

As chain length increases, the boiling and melting point increases
As chain length increases, the molecules get longer
As molecules get longer, there are more surface area contacts
As there are more surface area contacts, the London forces of attraction are stronger
As the London forces of attraction are stronger, more energy is required to overcome these forces of attraction so the boiling point increases

Question 7

What are alcohols soluble in and why?

Answer 7

• alcohols are soluble in polar solvents ‘like dissolves like’
• the -OH group is polar and so are water molecules
• alcohol molecules can form hydrogen bonds with water molecules

Question 8

What are the differences between alcohols and alkanes?

Answer 8

Alcohols are able to form intermolecular hydrogen bonds whilst alkanes are unable to

Hydrogen bonds are the strongest type of intermolecular force

Alcohols have a higher boiling point than it’s corresponding alkane i.e. propane : -42 propanol:97

Alcohols are less volatile as their boiling points are higher than alkanes

Question 9

What does volatility mean?

Answer 9

Volatility is the tendency of a substance to evaporate

Question 10

What happens when an alcohol is oxidized?

Answer 10

Through the process of oxidation, alcohols lose atoms of hydrogen
These atoms are lost from :
The -OH group
The carbon bonded to the -OH group

Question 11

What happens when primary alcohols are oxidized?

Answer 11

They lose hydrogen atoms from the -OH and one hydrogen bonded to a carbon atom

Question 12

Are secondary and tertiary alcohols easily oxidized?

Answer 12

Secondary alcohols can be easily oxidized

Tertiary alcohols can’t be easily oxidized ash it doesn’t have a H atom on the C of the C-OH group so they aren’t.

Question 13

What are the conditions of the reaction of a primary alcohol to form an aldehyde?

Answer 13

A catalyst: sulphuric acid / acidified potassium dichromate

acidified potassium dichromate Because it is the oxidizing agent and acts as a source of oxygen

Gentle heating
Immediate distilling:if we want to obtain this aldehyde we need to immediately distill the mixture to prevent any further reaction

There should be a color change from orange to green

Question 14

What happens if the mixture of the reaction between an alcohol to form an aldehyde isn’t
Distillied immediately?
And it’s conditions

Answer 14

A further reaction will occur to form a carboxylic acid

-heating under reflux: this is a process of constant boiling and condensing and it ensures that the reaction goes to completion and minimizes the loss of reactants and products as vapor
Excess acidified potassium dichromate
There should be a color change from. Orange to green

Question 15

For the remainder :

Answer 15

https://www.youtube.com/watch?v=ImVzxe9jmPw&list=PLkocNW0BSuEFvnpnhj8fKN-KFUOlnKiT0&index=17