4a. Introduction

Question 1

4.1 What is a hydrocarbon

Answer 1

A compound that contains hydrogen and carbon atoms only.

Question 2

4.2 What is the molecular formula

Answer 2

The actual number of atoms in a molecule

Question 3

4.2 What is the empirical formula

Answer 3

The simplest whole number ratio of atoms in a molecule

Question 4

4.2 What is the general formula

Answer 4

Shows the relationship between the number of atoms of one element to another within a molecule

Question 5

4.2 What is the structural formula

Answer 5

Show how the atoms in a molecule are joined together

Question 6

4.2 What is the displayed formula

Answer 6

Full structural formula which shows the spatial arrangement of all the atoms and bonds in a molecule

Question 7

4.2 What is another name for displayed formula

Answer 7

Graphical formula

Question 8

4.3 What is meant by homologous series

Answer 8

Is a series of organic compounds that have similar features and chemical properties due to them having the same functional group

All members of a homologous series have:

the same general formula,
same functional group,
Similar chemical properties,
gradation in their physical properties

Question 9

4.3 What is meant by functional group

Answer 9

A group of atoms bonded in a specific arrangement that influences the properties
of the homologous series

Question 10

4.3 What is meant by isomerism

Answer 10

Isomers are compounds that have the same molecular formula but different displayed formulae

Question 11

4.3 Give an example of an isomer

Answer 11

propene and cyclopropane

Question 12

4.6 What can the reactions of organic compounds be classified into

Answer 12

Substitution
Addition
Combustion

Question 13

4.6 What is a substitution reaction

Answer 13

A substitution reaction takes place when one functional group is replaced by another

Question 14

4.6 Give an example of a substitution reaction involving methane - word equation

Answer 14

methane + bromine → bromomethane + hydrogen bromide

Example: Methane reacts with bromine under ultraviolet light

Question 15

4.6 Give the chemical equation for methane reacting with bromine

Answer 15

CH4 + Br2 → CH3Br + HBr

Question 16

4.6 What is an addition reaction

Answer 16

When two or more molecules combine to form a larger molecule with no other products

Question 17

4.6 Give the word equation of the addition reaction between ethene and bromine

Answer 17

Example: Bromine will react with ethene and the bromine molecule will react and add across the double bond of the ethene

ethene + bromine → dibromoethane

Question 18

4.6 Give the chemical formula for the addition reaction of ethene and bromine

Answer 18

C2H4 + Br2 → C2H4Br2

Question 19

4.6 What is a combustion reaction

Answer 19

When an organic substance reacts with oxygen to form carbon dioxide (or carbon monoxide if incomplete combustion) and water.

Question 20

4.6 What kind of reaction occurs when alkenes are heated in an air of oxygen

Answer 20

Complete combustion

Question 21

4.6 What is the chemical equation for the complete combustion of CH4 and oxygen

Answer 21

CH4 + 2O2 → CO2 + 2H2O