3.2 - Alkanes

Question 1

What are the 3 stages of the mechanism of Halogenation of Alkanes?

Answer 1

|> Initiation
|> Propagation
|> Termination

Question 2

Name of mechanism: Halogenation of Alkanes

Answer 2

Free-radical Substitution

Question 3

Define: Propagation (free-radicals)

Answer 3

Formation of Free Radicals

Question 4

What is produced from catalytic cracking?

Answer 4

|> Cyclic & branched Alkanes

|> Aromatic Rings (e.g. Benzene)

Question 5

Define: Initiation (free-radicals)

Answer 5

Formation of radicals under UV light

Question 6

What does Thermal Cracking produce?

Answer 6

|> Alkanes

|> High % of Alkenes

Question 7

What are the Catalysts used in Catalytic Converters?

Answer 7

Rh, Pd, Pt

Question 8

As the length of a carbon chain increases, the boiling point ____ ?

Answer 8

Increases

Question 9

Why are power station chimneys coated with CaO or CaCO₃?

Answer 9

Remove Sulfur Dioxide from Flue Gas

Form Plasterboard

Question 10

What are the Conditions for Halogenation of Alkanes?

Answer 10

U.V. Light

Question 11

Why does boiling point decrease as no. of branches increases?

Answer 11

|> Less points of contact
|> VDWs become weaker
|> Less energy to break

Question 12

What conditions is Thermal Cracking carried out at?

Answer 12

v. High Temp

High Pressure

Question 13

Why are Alkanes not soluble in Water?

Answer 13

|> They are non-polar

|> Water molecules are held together by hydrogen bonds, which are much stronger than VDWs

Question 14

What is produced from Further Incomplete combustion of Alkanes?

Answer 14

solid C & H₂O

Question 15

Define: Structural isomers

Answer 15

Molecules with the same molecular formula but a different structural formula

Question 16

What are the products of Catalytic Cracking used for?

Answer 16

Motor Fuels

Question 17

Why does boiling point Increase as Chain Length Increases?

Answer 17

|>More electrons
|>Stronger temporary dipoles
|>More energy needed to break

Question 18

Define: Saturated Hydrocarbons

Answer 18

Only contain single C-C bonds

Question 19

Define: Cycloalkane

Answer 19

|> Have general formula CnH₂n

|> Named according to largest ring

Question 20

What Inter-molecular forces attract neighbouring Alkane molecules?

Answer 20

weak VDWs

Question 21

As the number of Branches in an Alkane Increases, the boiling point ____ ?

Answer 21

Decreases

Question 22

What is produced from Incomplete combustion of Alkanes?

Answer 22

CO & H₂O

Question 23

Are alkanes polar or non-polar?

Answer 23

|> Non-polar

|> C & H have similar electronegativity vaues

Question 24

Define: Hydrocarbon

Answer 24

Compounds that contain Carbon & Hydrogen atoms only

Question 25

What is produced from Complete combustion of Alkanes?

Answer 25

CO₂ & H₂O

Question 26

Define: Free-radical

Answer 26

Species with an Unpaired electron

Question 27

What type of reaction is Halogenation?

Answer 27

Substitution

H atom replaced by Halogen atom

Question 28

Define: Chain isomers

Answer 28

Same molecular formula, different longest chain lengths with -yl groups

Question 29

Why are Alkanes non-polar?

Answer 29

C & H have very similar electronegativity values

Question 30

Shape and Bond Angle around a C atom?

Answer 30

Tetrahedral

109.5°

Question 31

What is the general formula for Aliphatic (chain) Alkanes?

Answer 31

CnH₂n₊₂

Question 32

Why do catalytic converters have a honeycomb structure?

Answer 32

Larger Surface Area

Question 33

What do Catalytic Converters remove?

Answer 33

CO, NOₓ & unburned hydrocarbons

Question 34

How is Catalytic Cracking carried out?

Answer 34

High Temperature
Slight Pressure
Zeolite (porous solid) Catalyst

Question 35

How are Nitrogen Oxides (NOₓ) produced?

Answer 35

N₂ + O₂ & electrical spark