Alcohols

Question 1

what is the general formula for an alcohol?

Answer 1

CnH2n+1OH

Question 2

How do we know if a an alcohol is primary, secondary or tertiary?

Answer 2

It depends on which carbon atom the OH group is bonded to.

Question 3

Describe how ethanol could be converted into bromoethane.

Answer 3

Substitution reaction

• react with halide ion (NaBr) and concentrated sulfric acid

Question 4

How do the volatilities of alcohols compare with the volatilities of similarly sized alkanes?

Answer 4

• Alcohols can hydrogen bond with each other
• Hydrogen bonding is the strongest type of intermolecular force and so alcohols have higher boiling points than other similarly sized alkanes
• Therefore alcohols are less volatile

Question 5

What products are made when 2-methylpropan-2-ol is mixed with sodium bromide and concentrated sulfric acid?

Answer 5

make a haloalkane

• 2-bromo-2-methylpropane

Question 6

Can alcohols dissolve in water and why?

Answer 6

Yes but this only applies to shorter chain molecules
• alcohol react with water via a hydrogen bond. This is because the positive charge on the hydrogen is attracted to the lone pair of electrons on the water.

Question 7

Alkenes can be made from the __________

Answer 7

Dehydration of Alcohols

Question 8

A dehydration reaction involves the use of _________

Answer 8

• An acid catalyst

* either concentrated sulphuric or phosphoric acid

Question 9

Haloalkanes are made from __________

Answer 9

Alcohols via a substitution reaction.

Question 10

A haloalkane is made when an alcohol is reacted with _________

Answer 10

• A halide ion source (e.g. NaBr)

* an acid catalysts (H2SO4)

Question 11

Dehydration of non primary alcohols can lead to _________

Answer 11

3 different Alkenes

Question 12

When alcohols are burned what is produced?

Answer 12

they react with oxygen in the air and make CO2 and H2O

Question 13

Alcohols can be oxidised by using a ________ like _______

Answer 13

• mild oxidising agent

* potassium dichromate

Question 14

Alcohols can be oxidised to ______, ________ and _______

Answer 14

1) aldehydes
2) keytones
3) carboxylic acids

Question 15

How are alcohols oxidised?

Answer 15

using acidified potassium dichromate

Question 16

what colour will the acidified potassium dichromate turn when reduced?

Answer 16

It will go from orange (dichromate ion) to green (chromate ion)

Question 17

Can alcohols hydrogen bond with each other?

Answer 17

yes

Question 18

Why are alcohols less votaile than molecules with similar relative mass?

Answer 18

Because alcohols have hydrogen bonding - strongest type of intermolecular force - therfore they have higher boiling points than molecules of a similar realative mass with no hydrogen bonding.

Question 19

Why are alcohols combusted?

Answer 19

• they are used as fuels to generate energy

* when burn they reactvwith oxygen in the air to make CO2 and H2O. The alcohol is oxidised