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Flashcards in Revision Guide - Cracking Crude oil Deck (17):
1

What is cracking?

Splitting long chained hydrocarbons 

2

What does cracking produce?

Some useful fuels

 

ETHENE 

→ Most of the products of cracking are alkAnes

3

What sort of reaction is cracking?

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

4

How is cracking done?

  • 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

5

What are alkenes?

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

6

Are alkenes saturated or unsaturated?

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

7

What are the first 2 alkenes?

Ethene and propene

8

General formula of alkEnes?

CnH2n

9

How can you test fo alkenes? (double bonds)

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

10

How can ethanol be made?

Hydrating ethene with steam in the prescence of a catalyst

11

good things about production of ethanol but bad things?

  • 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

12

How can ethanol be produced from renewable sources?

Sugar is converted to ethanol by fermentation

sugar → carbon dioxde + ethanol

13

Advantage of producing ethanol from renewable sources?

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

14

isadvantages of making ethanol from renewable sources?

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

15

How  can alkenes be used to make polymers?

By polymerisation 

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

16

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

Polyethene

17

What does the propertes of polymers depend on?

What its made from 

The pressure and temperature at which it was made in polymerisation