10. Alkanes/ Alkenes/ Alkanols

Question 1

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

Answer 1

Question 2

What is meant by a saturated hydrocarbon?

Answer 2

A hydrocarbon where all C-C bonds present are single

Question 3

What is a “hydrocarbon”?

Answer 3

A compound containing only C and H atoms

Question 4

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

Answer 4

Tetrahedral

Question 5

What is shown by a “Molecular Formula” ?

Answer 5

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

e.g

H₂O

C₃H8

NH₃

CO₂

Question 6

What is shown in a “Full Structural Formula”?

Answer 6

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

Question 7

What is shown in a shortened structural formula?

Answer 7

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 8

What is the general formula of the alkanes?

Answer 8

Question 9

What are the 2 main reactions of alkanes?

Answer 9

1. Combustion
2. Catalytic cracking

Question 10

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

Answer 10

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

Question 11

What are the products of alkane combustion?

Answer 11

CO₂ and H₂O

Question 12

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

Question 13

What is a “functional group”?

Answer 13

The part of a molecule which gives it its chemical (and physical) properties

Question 14

What is the functional group in the alkenes?

Answer 14

The C=C bond

Question 15

How can we obtain alkenes?

Answer 15

By catalytic cracking of loneger chain alkanes

Question 16

What is the general formula of the alkenes?

Answer 16

C_n H_2n

Question 17

What is the general formula of the Alkanols?

Answer 17

C_n H_2n+1 OH

Question 18

What are the 2 ways to make ethanol?

Answer 18

Question 19

What are some uses of ethanol?

Answer 19

Question 20

Why is pure ethanol unable to conduct electricity?

Answer 20

It is a covalent molecule which doesn’t break down into ions

Question 21

What is the functional group in Alkanols?

Answer 21

The hydroxyl group

Question 22

Why are alkanols miscible with water

Answer 22

The hydroxyl group is polar

Question 24

What are the 2 main reactions of alkenes?

Answer 24

1. Addition (particularly with water to make alkanols)
2. Polymerisation (to make plastics)

Question 25

What is meant by a “raw material” ?

Answer 25

A substance readily available in the earth’s crust.

e.g

Sodium chloride

Water

crude oil

Question 26

What happens in a “hydration “reaction?

Answer 26

A water molecule is added to a molecule with a C=C bond.

Question 27

What happens in a “hydrogenation” reaction?

Answer 27

Hydrogen is added across a C=C bond

Question 28

What happens in a “dehydration” reaction?

Answer 28

A water molecule is removed from an alkanol

Question 29

What is the catlayst used in a dehydration reaction?

Answer 29

Hot aluminium oxide

Question 30

What are the 2 reactions of alkanols?

Answer 30

1. Combustion
2. Dehydration

Question 31

What is a Homologous Series?

Answer 31

Molecules with

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