Organic 2

What is fractional distillation

Separation of a mixture into fractions based on boiling points

What carbon range is refinery gas

C1 to C4

What carbon range is light gasoline

C5 to C10

What is naptha

petrol, feedstock for petrochemical industry

What is kerosene used for

Aircraft fuel and paraffin lamps

What is gas oil used for

Diesel and lubricating oil

What is residue used for

Bitumen and heavy industrial fuel

What does LPG stand for

Liquefied petroleum gas

What gases are in LPG

Propane and butane

Why are mercaptans added to natural gas

To give a smell so leaks are detected

What is auto ignition?

The early explosion of a petrol-air mixture caused by increasing pressure in the engine.

What is knocking?

Auto ignition in an engine

What hydrocarbons cause knocking

Long straight chain hydrocarbons

What structure gives smoother burning

Branched chain hydrocarbons

What is octane number

The octane number of a fuel is the measure of its tendency to resist ‘knocking’.

Octane number of 100

2, 2, 4 trimethylpentane

Octane number of 0

heptane

Name three features that increase octane number

Short chain, branched, cyclic/aromatic

What is reforming

Changing straight chains into branched or cyclic hydrocarbons

What is isomerisation

Straight chain hydrocarbons changed to branched isomers

What is dehydrocyclisation

Straight chains changed to rings and aromatics

What gas is formed in dehydrocyclisation

Hydrogen

Why are aromatics useful in petrol

They have high octane numbers

Why can aromatics be a problem

Some are carcinogenic

What is cracking

Long chains broken into shorter useful chains

What are oxygenates

Oxygen containing petrol additives

Give two oxygenates

Alcohol and MTBE

Why add oxygenates to petrol

Increase octane number and reduce carbon monoxide

What lead is added to petrol to increase octane number

tetraethyl lead

Why was leaded petrol phased out

Lead is toxic and poisons catalysts

What does a catalytic converter do

Reduces harmful exhaust gases

Name 3 catalytic converter catalysts

Platinum, palladium, rhodium

What does lead do to catalytic converters

Poisons the catalysts

How is ethene prepared?

Dehydration of ethanol

What does dehydration mean?

Removal of water

What type of reaction forms ethene from ethanol

Elimination

Ethene preparation equation

C₂H₅OH → C₂H₄ + H₂O

What catalyst is used to prepare ethene

Aluminium oxide

What colour is aluminium oxide

White

Function of glass wool in ethene prep

Soaks up ethanol and holds it in place

Why discard first ethene sample

It contains mostly displaced air

How prevent suck back in ethene prep

Remove delivery tube before stopping heating

Why can ethene be collected over water

It is insoluble in water

Ethene physical appearance

Colourless gas with sweetish smell

Ethene combustion equation

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

Ethene flame

Luminous flame with slight smoke

What does milky limewater prove

Carbon dioxide formed

What is unsaturation?

Contains carbon carbon double or triple bond

Test for unsaturation with bromine water

Red brown to colourless

Product of ethene and bromine

1 2 dibromoethane

Test for unsaturation with manganate

Purple to colourless

What is ethyne also called

Acetylene

What is ethyne used for

Cutting and welding metals

How is ethyne prepared

Calcium carbide reacts with water

Ethyne preparation equation

CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂

What is calcium carbide appearance

Greyish solid

Observation when water hits calcium carbide

Effervescence

What white substance forms in ethyne prep

Calcium hydroxide

Why discard first ethyne sample

It contains mostly displaced air

Why not touch calcium carbide

Sweat may start the reaction

How to remove ethyne impurities

Use acidified copper sulfate solution

Name ethyne impurities

Phosphine and hydrogen sulfide

Where do ethyne impurities come from

Calcium phosphide and calcium sulfide

Ethyne physical appearance

Colourless gas with sweetish smell if pure

Why can ethyne be collected over water

It is insoluble in water

Ethyne flame

Smoky luminous flame

Why is ethyne flame smoky

Unburned carbon forms soot

Test for ethyne with bromine water

Red brown to colourless

Ethyne bromine equation

C₂H₂ + 2Br₂ → C₂H₂Br₄

Test for ethyne with manganate

Purple to colourless