Revision Guide - Cracking Crude oil

Question 1

What is cracking?

Answer 1

Splitting long chained hydrocarbons

Question 2

What does cracking produce?

Answer 2

Some useful fuels

ETHENE

→ Most of the products of cracking are alkAnes

Question 3

What sort of reaction is cracking?

Answer 3

A thermal decomposition reaction (breaking molecules down by heating them)

Question 4

How is cracking done?

Answer 4

• Heat the long chained hydrocarbon to vapourise it
• The vapour is then passed over a powdered catalyst at a temperature of about 400℃ - 700℃
• The catalyst is Aluminium Oxide

Question 5

What are alkenes?

Answer 5

Hydrocarbons which have a double bond between two of the carbon atoms in their chain

Question 6

Are alkenes saturated or unsaturated?

Answer 6

Unsaturated because that can make more bonds (the double bond can open uo allowing the two carbon atoms to bond with other atoms)

Question 7

What are the first 2 alkenes?

Answer 7

Ethene and propene

Question 8

General formula of alkEnes?

Answer 8

C_nH_2n

Question 9

How can you test fo alkenes? (double bonds)

Answer 9

B adding the substance to bromine water

An alkene will decolourise the bromine water, turning it from orange to colourless

This isbecause the double bond has opened up and formed bonds with the bromine

Question 10

How can ethanol be made?

Answer 10

Hydrating ethene with steam in the prescence of a catalyst

Question 11

good things about production of ethanol but bad things?

Answer 11

• At the moment its cheap (because the ethene is cheap and not much is wasted)
• However, ethene is produces from crude oil which is non-renewable that will run out, which will make it more expensive

Question 12

How can ethanol be produced from renewable sources?

Answer 12

Sugar is converted to ethanol by fermentation

sugar → carbon dioxde + ethanol

Question 13

Advantage of producing ethanol from renewable sources?

Answer 13

The process needs a lower temperature and simpler equipment

Raw material is renewable

Ethanol can be used as a cheap fuek in countries which don’t have oil reserves for making petrol

Question 14

isadvantages of making ethanol from renewable sources?

Answer 14

The ethanol from this process isn’t very concentrated

→ So if you want to incease its strength you have to distil it

It also needs to be purified

Question 15

How can alkenes be used to make polymers?

Answer 15

By polymerisation

→ The joining together of small alkene molecules (monomers) to from very large molecules - polymers

Question 16

What is the product called when many ethene molecules are joined up/?

Answer 16

Polyethene

Question 17

What does the propertes of polymers depend on?

Answer 17

What its made from

The pressure and temperature at which it was made in polymerisation