Chemistry 2.5 Crude Oil, Fuels and Organic Chemistry

Crude oil

A finite resource formed from marine organisms over millions of years containing a mixture of hydrocarbons

Fractional distillation of crude oil

Crude oil is heated hydrocarbons evaporate rise up the column and condense at different temperatures with bitumen left at the bottom

Fractions

Mixtures of hydrocarbons with similar boiling points

Trends with increasing chain length

Higher boiling and melting points higher viscosity darker colour less flammable less volatile and less useful as fuels

Economic importance of oil

Oil prices affect the global economy and supply issues can impact countries especially poorer ones

Political importance of oil

Major oil producing countries can control supply as a political tool

Social impact of oil

Provides jobs and income to the economy

Environmental impacts of oil

Burning releases carbon dioxide drilling damages habitats and oil spills harm wildlife

Complete combustion of hydrocarbons

Hydrocarbon reacts with oxygen to form carbon dioxide and water

Incomplete combustion of hydrocarbons

Hydrocarbon reacts with limited oxygen to form carbon monoxide and water

Calorimetry

A method used to measure the energy released when a fuel burns

Calorimetry method

Burn fuel to heat water measure temperature change and calculate energy released

Combustion of hydrogen

Hydrogen reacts with oxygen to form water and is used as a fuel in rockets and cars

Advantages of hydrogen fuel

No greenhouse gases produced and an alternative to fossil fuels

Disadvantages of hydrogen fuel

Highly flammable difficult to store and often produced using fossil fuels

Fire triangle

Fire requires oxygen fuel and heat and removing one stops the fire

Hydrocarbon cracking

Breaking long chain hydrocarbons into shorter more useful molecules

Products of cracking

Alkanes and alkenes which are used to make plastics

General formula of alkanes

CnH2n plus 2

General formula of alkenes

CnH2n

Examples of simple alkanes

Methane CH4 ethane C2H6 propane C3H8 butane C4H10

Examples of simple alkenes

Ethene C2H4 propene C3H6 butene C4H8

Isomerism

Compounds with the same molecular formula but different structures

Isomerism in alkanes

Different carbon chain arrangements with the same molecular formula

Isomerism in alkenes

Same molecular formula but double bond in different positions

Naming alkanes and alkenes

Find longest chain number from nearest group list branches alphabetically and locate double bonds

Addition reactions

Two or more molecules join to form one larger molecule with no other products

Test for alkenes

Bromine water turns from orange to colourless

Addition polymerisation

Alkene monomers join together to form polymers such as polyethene

Uses of polyethene

Bin liners plastic bottles pipes and plastic bags

Uses of polypropene

Car parts packaging and textiles

Uses of PVC

Pipes electrical cables window frames and medical tubing

Uses of PTFE

Non stick pan coatings nail polish and hair styling tools

Properties of polymers

Some soften when heated some do not and higher density polymers are stronger

Environmental issues with plastics

Non biodegradable and increase landfill waste

Plastic disposal methods

Landfill incineration and recycling

Ethanol production

Produced by fermentation of sugar using yeast producing ethanol and carbon dioxide

Test for alcohol

Potassium dichromate and sulfuric acid turns from orange to green when heated

Uses of ethanol

Alcoholic drinks solvent and fuel

Social impacts of alcohol

Health problems and increased crime

Economic impacts of alcohol

Provides jobs and tax income but increases healthcare and policing costs

Advantages of ethanol fuel

Carbon neutral renewable and useful for countries without oil

Disadvantages of bioethanol

Uses energy land food resources and engines may need modification

Naming alcohols

Use suffix ol with position of the OH group and diol or triol for multiple groups

Isomers of alcohols

Same molecular formula but OH group in different positions

Microbial oxidation of ethanol

Ethanol is oxidised to ethanoic acid by microbes

Infrared spectroscopy

A technique used to identify bonds and functional groups using infrared light