Unit 2-Everyday consumer products

Question 1

Describe how to identify an alcohol:

1. From the name
2. From a structure

Answer 1

1. Name ends in “-ol”
2. Structure contains the hydroxyl group -O-H

Question 2

What is the general formula of alcohols?(also known as alkanols)

Answer 2

C_nH_2n+1OH

Question 3

What are the steps need to name alcohols?

Answer 3

1. Identify longest chain of carbons (methan- ,ethan- etc)
2. The hydroxyl functional group is the most important part of the molecule and the carbon chain is numbered to give it the lowest branch number
3. Add -ol to the end

Examples Propan-2-ol and Pentan-1-ol

Question 4

Describe the chemical properties and uses of alcohols.

Answer 4

Chemical properties of alcohols include that they are flammable and they react with carboxylic acids to form esters.

Alcohols are used as fuels as they are highly flammable and burn with very clean flames.

Used as solvents.

Question 5

Describe how to identify a carboxylic acid:

1. From the name
2. From a structure

Answer 5

1. The name ends in -oic acid
2. The structure contains the carboxyl functional group

–COOH

Question 6

What is the general formula of carboxylic acids?(also known as alkanoic acids)

Answer 6

C_nH_2nO₂

Question 7

What are the steps need to name carboxylic acids?

Answer 7

1. Identify longest chain of carbons (methan- ,ethan- etc)
2. The position of the carboxyl group does not need to be identified with a number, as it is always found at the end of the carbon chain, and so is on the first carbon.
3. Add oic acid to the end

Examples Methanoic acid and Butanoic acid

Question 8

Describe the chemical properties and uses of carboxylic acids.

Answer 8

Chemical properties of carboxylic acids to include
1. pH

2. Reactions with metals, oxides, hydroxides and carbonates
3. reaction with alcohols to form esters

Vinegar is a solution of ethanoic acid. Vinegar is used in household cleaning products and as a preservative in the food industry.

Question 9

Identify the: (a) Alcohol (b) Carboxylic Acid

from the names below

(i) Heptan-2-ol
(ii) Octanoic acid

Answer 9

(ii) Heptan-2-ol = (a) alcohol
(iii) Octanoic acid = (b) carboxylic acid

Question 10

Identify the: (a) Alcohol (b) Carboxylic Acid

from the formulae below

(i) H₃C-​CH₂-​CH(OH)-CH₃
(ii) H₃C-CH₂-COOCH₃
(iii) H₃C-CH₂-COOH

Answer 10

(i) butan-2-ol = (a) alcohol
(iii) propanoic acid = (b) carboxylic acid

Question 11

What is the systematic name of this molecule?

Answer 11

2-methylpropanoic acid

Question 12

What is the systematic name of this molecule?

Answer 12

2-ethylbutan-1-ol

Question 13

3Comparing ethane, ethene, ethanol and ethanoic acid shows that ethanoic acid has the highest MP and BP.

Why?

Answer 13

This is because the ethanoic acid molecules are held more tightly together (by intermolecular forces) and require more energy to separate.

Question 14

Methane is a covalent molecular substance.

It has a low boiling point and is a gas at room temperature.

Explain why methane is a gas at room temperature.

Answer 14

Weak intermolecular attractions or weak bond attraction between molecules