Topic 6(B&C): Alkanes & Alkenes

Question 1

During cracking why are a variety of Alkenes & Alkanes formed with different chain lengths?

Answer 1

• C-C bond can break anywhere

Question 2

Fractional Distillation

Answer 2

1. Crude oil is heated in a furnace which turns most of it into vapour
2. Near the top is where the shorter chain molecules condense
3. Near the bottom is where longer molecules are as they have a higher melting point
4. Different columns have different temperatures where different length carbon chains condense

Question 3

Cracking

Answer 3

• Converts longer chain Hydrocarbons into smaller ones

- Heated with a ZEOLITE catalyst

Question 4

Reforming

Answer 4

conversion of straight-chain hydrocarbons into branched-chain and cyclic hydrocarbons for EFFICIENT COMBUSTION

Question 5

What pollutants are there from unburned combustion?

Answer 5

• Oxides of sulfur (SO2&SO3) (can cause acid rain)
• Oxides of nitrogen (NO&NO2) (can cause Acid rain)
• CO
• Unburned carbon (soot)

Question 6

Catalytic converter : outline the stages of how NO & CO react in a catalytic convertor

Answer 6

• CO & NO are absorbed onto the surface of the catalyst
• The catalyst weakens the bonds so CO2 and N2 can be made
• Products desorbs from the surface

Question 7

Hydrogenation (manufacture of margarine)

Answer 7

• Converts alkenes into alkanes
• Addition of Hydrogen (H2)
• Needs a Nickel catalyst

Question 8

Halogenation

Answer 8

•Involves the addition of a halogen

Question 9

Addition reaction

Answer 9

•Two molecules combine to form one molecule

Question 10

What do Curly arrows represent?

Answer 10

•Movement of electron pairs

Question 11

Electrophile

Answer 11

• Species that is attracted to a region of HIGH electron density

Question 12

Electrophilic addition
(define addition and define what is attacking it)

Answer 12

• Two molecules form one molecule

* The attacking molecule is an electrophile

Question 13

Heterolytic fission

Answer 13

Breaking of a covalent bond so that both bonding electrons are taken by one atom forming ions ( the more electronegative one)

Question 14

Carbocation

Answer 14

A positive ion in which the charge is shown on the carbon atom

Question 15

What is a major product?

Answer 15

The most stable product (most R groups attached)

Question 16

What is an unsymmetrical alkene?

Answer 16

Atoms on either side of the C=C are not the same

Question 17

Monomers

Answer 17

Small molecules that combine to form a polymer

Question 18

Nucleophile

Answer 18

Species that donate a lone pair of electrons to form a covalent bond with an electron-deficient atom

Question 19

Hydrolysis

Answer 19

Water or hydroxide ions replace an atom in a molecule

Question 20

Test for Alkenes

Answer 20

Bromine water goes colourless