Other useful substances from crude oil

Question 1

How can hydrocarbons be made more useful?

Answer 1

Cracking - producing smaller molecules by heating them to vapour, then either passed over a hot catalyst or mixed with steam and heated so that thermal decomposition occurs

Question 2

What are the products of cracking? How are they useful?

Answer 2

Smaller alkanes and alkenes, which are unsaturated hydrocarbon molecules with the general formula CnH2n
Some of these are useful as fuels, or else for making polymers

Question 3

In a displayed structure of an alkene, what does = represent?
How many double bonds does an alkene have?

Answer 3

A double bond

1

Question 4

How do alkenes affect bromine water?

Answer 4

They turn it from orange to colourless

Question 5

What is polymerisation?

Answer 5

When small molecules (monomers) such as alkenes join together to form very large molecules (polymers
An example is ethene going to poly(ethene)
Ability to draw displayed structure diagrams of polymers is needed

Question 6

Give uses of modern polymers

Answer 6

Packaging materials, waterproof coatings for fabrics, dental polymers, wound dressings, hydrogels and smart materials (including shape memory polymers)

Question 7

Define biodegradable
Are most polymers biodegradable or not?
What are the problems with this

Answer 7

A substance that can be broken down by microbes
Not
Problems with waste disposal include increasing eye-sore landfill sites, nasty smells for people living near landfill sites

Question 8

Describe how more biodegradable plastics are being developed

Answer 8

Plastics made from cornstarch and polymers are being used for plastic bags

Question 9

How can ethanol be produced? Give two ways

Answer 9

Hydration of ethene with steam in the presence of a catalyst (non-renewable)
Fermentation of yeast i.e. sugar –> carbon dioxide + ethanol (renewable)

Question 10

What are the social and economic advantages and disadvantages of using products from crude oil as fuels or as raw materials for plastics and other chemicals?

Answer 10

Most polymer plastics have very numerous uses in technology, building and daily life. This means they can be sold for lots of money
Alkenes can be sold as expensive fuels
Crude oil is a limited resource

Question 11

What are the advantages and disadvantages of making ethanol from renewable and non-renewable sources?

Answer 11

R: sugars come from renewable plants, batch process (stop-start), more workers needed, slower, 30ºC and 1 atm pressure needed, impure (needs treatment), little energy needed
Non: ethene comes from non-renewable crude oil, continuous process (runs all the time), fewer workers needed, faster, 300ºC and 60-70 atm pressure needed, lots of energy needed