9. Hydrocarbons

Question 1

What is a “hydrocarbon”?

Answer 1

A compound containing only C and H atoms

Question 2

What is a Homologous Series?

Answer 2

Molecules with

• same general formula
• similar chemical properties
• gradation in physical properties

Question 3

What are the names of the alkanes from 1C to 8C atoms in molecules?

Answer 3

Question 4

What is meant by a saturated hydrocarbon?

Answer 4

A hydrocarbon where all C-C bonds present are single

Question 5

What is the 3D shape of methane (CH₄) ?

Answer 5

Tetrahedral

Question 6

What is shown by a “Molecular Formula” ?

Answer 6

The types of atom and their relative abundance in a molecule. The abundance is shown as subscript

e.g

H₂O

C₃H8

NH₃

CO₂

Question 7

What is shown in a “Full Structural Formula”?

Answer 7

All the atoms and all the covalent bonds connecting them in a molecule

Question 8

What is shown in a shortened structural formula?

Answer 8

Each C in the chain is shown with everything bonded to it (not other C atoms in chain) No bonds need to be shown , although C=C bonds are allowed

Question 9

What is the general formula of the alkanes?

Answer 9

Question 10

What are the 2 main reactions of alkanes?

Answer 10

1. Combustion
2. Catalytic cracking

Question 11

Why is catalytic cracking an important reactions for longer chain alkanes?

Answer 11

1. To produce shorter chain, more useful alkanes
2. To obtain alkenes which are useful reactants to make other products

Question 12

What are the products of complete alkane combustion?

Answer 12

CO₂ and H₂O

Question 13

How do we test for the products of combustion of a hydrocarbon?

Answer 13

Question 14

What are possible harmful products of incomplete combustion of hydrocarbons?

Answer 14

Question 15

What is meant by the term “isomers”?

Answer 15

Compounds with the same molecular formula but different structural formula.

Question 16

Why does the boiling point of the alkanes increase as you add C (and H) atoms?

Answer 16

The larger molecules have stronger attractions between them that require more energy to be broken

Question 17

What is meant by an unsaturated hydrocarbon?

Answer 17

A hydrocarbon with (at least) one C=C bonds present

Question 18

What is a “hydrocarbon”?

Answer 18

A compound containing only C and H atoms

Question 19

What is a Homologous Series?

Answer 19

Molecules with

• same general formula
• similar chemical properties
• gradation in physical properties

Question 20

What is the general formula of the alkenes?

Answer 20

C_n H_2n

Question 21

What are isomers?

Answer 21

Compounds with the same molecular formula but different structural formulae

Question 22

How are alkenes produced?

Answer 22

Catalytic cracking of longer chain alkanes

Question 24

What is meant by a “functional group”?

Answer 24

The part of a molecule that is responsible for the chemical (and sometimes physical) properties of the compound.

Question 25

What is the functional group of the alkene family?

Answer 25

C=C bond

Question 26

What reactions do alkenes undergo?

Answer 26

Addition reactions

Question 27

What specific name to we give to to the addition a halogen to an alkene?

Answer 27

Halogenation

Question 28

What specific name to we give to to the addition of hydrogen to an alkene?

Answer 28

Hydrogenation

Question 29

What is produced when an alkene undergoes a hydrogenation reaction?

Answer 29

An alkane

Question 30

What is produced when an alkene undergoes a hydration reaction?

Answer 30

An alcohol

Question 31

What is the chemical test for presence of unsaturation (C=C bond)

Answer 31

Rapidly decolourises bromine solution.

Question 32

What specific name to we give to to the addition of water to an alkene?

Answer 32

Hydration

Question 33

What is the general formula for the cycloalkanes?

Answer 33

C_n H_2n

Question 34

Are cycloalkanes saturated or unsaturated?

Answer 34

They are saturated molecules.

Question 35

What are some uses of cycloalkanes?

Answer 35

• Fuels
• solvents