4.2.1 Alcohols

Question 1

General formula of alcohols

Answer 1

CnH2n+1OH

Question 2

Two methods to make alcohols

Answer 2

Fermentation or hydration

Question 3

How to identify 3 types of alcohol

Answer 3

Primary - carbon with OH attached has 1 other C atoms bonded.
Secondary - carbon with OH attached has 2 other C atoms bonded.
Tertiary - carbon with OH attached has 3 other C atoms bonded.

Question 4

Explanation of solubility

Answer 4

Water soluble as they are polar molecules as there is a large difference in electronegativity between C and O. The lone pair on O can H-bond with the H of a water molecule.

Question 5

boiling point of alcohols compared to equivalent alkanes

Answer 5

Higher than other organic molecules. The OH functional group is able to H-bond to the OH group on other alcohol molecules. H-bonds are the strongest intermolecular force meaning more energy is needed to overcome them.

Question 6

Combustion of alcohols

Answer 6

Alcohols make good fuels as lots of energy is released in combustion.
Alcohol + O2 –> CO2 + H2O

Question 7

What type of reaction occurs between an alcohol and halide ions

Answer 7

nucleophilic substitution

Question 8

Condition for halogenation of an alcohol

Answer 8

NaX/H2SO4

where X is the halogen

Question 9

Equation for reaction of ethanol with HBr and conditions

Answer 9

CH3CH2OH + HBr –> CH3CH2Br + H2O

Conditions: NaBr/H2SO4 to produce the HBr

Question 10

Type of reaction where an alkene is formed from an alcohol

Answer 10

Dehydration or elimination

Question 11

Conditions for forming an alkene from an alcohol

Answer 11

heat with concentrated phosphoric acid (H3PO40

Question 12

Primary alcohols are oxidised to form…

Answer 12

aldehydes and/or carboxylic acids

Question 13

Secondary alcohols are oxidised to form…

Answer 13

ketones

Question 14

Tertiary alcohols are oxidised to form..

Answer 14

N/A tertiary alcohols cannot easily be oxidised

Question 15

Conditions for forming an aldehyde from a primary alcohol

Answer 15

heat with acidified potassium dichromate and distil off the product

Question 16

Conditions for forming a carboxylic acid from a primary alcohol

Answer 16

reflux with acidified potassium dichromate

Question 17

Conditions for forming an ketone from a secondary alcohol

Answer 17

reflux with acidified potassium dichromate

Question 18

Observation of oxidation with acidified potassium dichromate

Answer 18

colour change orange –> green

Question 19

Equation for oxidation of ethanol to ethanal

Answer 19

CH3CH2OH + [O] –> CH3CHO + H2O

Question 20

Equation for oxidation of ethanol to ethanoic acid

Answer 20

CH3CH2OH + 2[O] –> CH3COOH + H2O

Question 21

Equation for oxidation of ethanal to ethanoic acid

Answer 21

CH3CHO + [O] –> CH3COOH

Question 22

Equation for oxidation of propan-2-ol to propanone

Answer 22

CH3CH(OH)CH3 + [O] –> CH3COCH3 + H2O

Question 23

Name the following:
CH3CH2CH2OH
CH3CH2CHO
CH3CH2COCH2CH3
CH3CH(OH)CH3

Answer 23

1. propan-1-ol
2. propanal
3. pentan-3-one
4. propan-2-ol

Question 24

Classify the following:
CH3CH2CH2OH
CH3CH2CHO
CH3CH2COCH2CH3
CH3CH(OH)CH3

Answer 24

1. primary alcohol
2. aldehyde
3. ketone
4. secondary alcohol

Question 25

Write the structural formula and classify the following:
2-methylpropan-2-ol
2-methylpropan-1-ol
butanone
butanoic acid

Answer 25

1. CH3C(CH3)(OH)CH3 (tertiary alcohol)
2. CH3CH(CH3)CH2OH (primary alcohol)
3. CH3COCH2CH3 (ketone)
4. CH3CH2CH2COOH (carboxylic acid)