Organic Chemistry Part 1 - Unit 2 Topic 5 Flashcards
How are fossil fuels formed?
Plants + animals died millions of years ago, buried in sediment in seas/swamps. Didn’t decay. Pressure + heat on these produced coal, oil + natural gas. (Made of hydrocarbons)
What are we using when we burn fossil fuels?
Sun’s energy which was stored as chemical energy millions of years ago.
What is crude oil made of?
How is crude oil removed?
Mixture of hydrocarbons
Drilling
Why can hydrocarbons be separated in crude oil?
Shorter molecules =
Different boiling points so separated by fractional distillation.
Lower temperature to condense at.
What is a hydrocarbon?
Molecule that contains only hydrogen and carbon.
What are fossil fuels?
Examples?
Formed over millions of years from dead plants + animals.
Crude oil, peat, lignite + natural gas.
What are renewable resources?
Examples?
Continuously supplied by nature as they are used by consumers.
Hydroelectric, wind, waves + solar energy.
What are non-renewable resources?
Fuels that are finite.
Once they are used up, they can’t be replaced.
What is fractional distillation?
How does it work?
Continual process of evaporation and condensation.
Heats crude oil piped in at bottom and various fractions constantly tapped off at different levels where they condense.
Bottom is warmer than top.
How does the petro-chemical industry work?
Extracts crude oil from source
Transported to refineries + fractionally distilled into separate hydrocarbons
Hydrocarbons used for fuels, manufacture of dyes, plastics, fertilisers, medicines, paints + lubricants.
3 environmental concerns of fossil fuels?
Transport of crude oil can lead to spills + leaks
Drilling for oil in sea bed can lead to leaks
Air pollution caused by burning fossil fuels as CO2 produced
What is LPG?
Liquid Petroleum Gas
What element does all fossil fuels contain?
Carbon
What is a homologous series?
Family of organic compounds
What do members of a homologous series have in common?
Same general formula, similar chemical properties, gradual change in physical properties, differ by CH2 unit.
Where are alkanes present?
What is their general formula?
Natural gas + petroleum
C(n)H(2n + 2)
What are 4 members of the alkanes? (Name, formula + state at room temp) What are alkanes called? What do they not have? What does this mean?
Methane, CH4, gas Ethane, C2H6, gas Propane, C3H8, gas Butane, C4H10, gas Saturated hydrocarbons Functional group Less reactive
What is the main use for hydrocarbons?
Fuels.
What is combustion?
Burning of a fuel in air (oxygen)
What are the products of combustion?
What is complete combustion?
What does incomplete combustion produce?
What flame does this gas burn with?
CO2 + H2O
Burning in an excess of air (all C turns to CO2)
CO + H2O
Clear blue flame
Equation for complete combustion with a hydrocarbon?
Equation for incomplete combustion with a hydrocarbon?
Hydrocarbon + oxygen -> carbon dioxide + water + (energy)
Hydrocarbon + oxygen -> carbon monoxide + water
What used to be the main gas used in the UK before natural gas was discovered?
Coal gas
What energy source can be used to make plastic?
Crude oil
What is bond breaking?
What is bond making?
Pulling atoms apart. Requires energy. Endothermic.
Making new bonds. Gives out energy. Exothermic.
What are 2 alkenes? (Name, formula + state at room temp)
Ethene (C2H4) Gas
Propene (C3H6) Gas
What is the general formula for alkenes?
What do all alkenes have?
What are they called?
What can they be used to make?
C(n)H(2n)
At least one double bond between 2 carbon atoms
Unsaturated hydrocarbons
Polymers
What are unsaturated hydrocarbons? E.g.
What are saturated hydrocarbons? E.g.
Have a double bond. Alkanes.
Don’t have a double bond. Alkenes.
What is the test to distinguish between an alkene and an alkane?
Shaking hydrocarbon in bromine water which adds across the double bond of alkene to produce a halogenalkane.
Alkane = Stays orange
Alkene = Turns colourless
What are 2 uses of polythene?
Cling film + bags
Write out structural formula of methane.
H
|
H------C------H
|
HWrite out structural formula of ethane.
H H
| |
H----C----C---H
| |
H HWrite out structural formula of propane.
H H H
| | |
H---C----C-----C----H
| | |
H H HWrite out structural formula of butane.
H H H H
| | | |
H—C—–C—-C—-C—-H
| | | |
H H H H
Write out structural formula of ethene.
H H | | C========C | | H H
Write out structural formula of propene.
H H H
| | |
H--C---C===C
| |
H HHow are fuels separated by fractional distillation?
Separate different fuels as they have different boiling points.
