Organic chemistry Flashcards
How are coal, oil and natural gas formed?
Formed as a result of heat and pressure
How is petroleum separated into smaller hydrocarbons?
Fractional distillation
Order of hydrocarbons in fractionating column
What is a fraction
A mixture of compounds with a similiar boiling point
What is refinery gas used for
Bottled gas
What is gasoline used for
Petrol
What is kerosene used for
Jet fuel
What is diesel used for
Train and car fuel
What is fuel oil used for
Central heating
What is bitumen used for
Road and roof tar
What is a homologous series
A family of hydrocarbons which have similiar features and chemical properties due to being in the same functional group
What test can be used to tell which is an alkane and which is an alkene
Bromine water -
Alkanes will be orange
Alkenes wil decolourise
What do all members of a homologous series have
Same general formula
Same functional group
Similiar chemical properties
Gradiation in their physical properties
Difference in molecular formula between one member and the next is CH2
What is a functional group
A group of atoms bonded in a specific arrangement which is responsible for the characteristic reactions of each member of a homologous series
What is a structural isomer
Compounds with the same molecular formula but different structural formula
There are two different types of structural isomer which are chain and position
In chain the structure of the carbon chain differs
In position the position of the functional group differs
example of chain isomer
example of position isomer
What are alkanes
Saturated hydrocarbons
Contain no double bonds
Colourless compounds which have a gradual change on their physical properties as the number of carbon atoms in the group increases
Generally unreactive compounds but they do ungo combustion reactions and can be cracked into smaller alkanes and react with halogens in the presence of light
What is the main component of natural gas
Methane
Combustion of methane
What is a substitution reaction
When do substitution reactions occur on alkanes
Substitution reaction - where one atom of one element/compound is swapped with an atom from another compound
Alkanes unergo substitution reactions with halogens in the presence of light
What are alkenes
Alkenes are hydrocarbons which contain a double bond
They are unsaturated compounds
How are alkenes and hydrogen made?
The catalyctic cracking of long alkane chains
What is catalyctic cracking?
The breakdown of less-useful longer hydrocarbon chains and shorter useful hydrocarbons
How is catalytic cracking conducted
Fractions containing large hydrocarbon molecules are heated at 600-700 degrees to vaporize them
Vapours are then passed over a catalyst of silica and alumina
This breaks the covalent bonds causing thermal decomposition
The longer hydrocarbon chain has been broken up into shorter chains of alkenes and alkanes
Example of alkanes being cracked
Kerosene and diesel oil are often cracked to form petrol other alkenes and hydrogen
How does bromine water show that one is an alkane and the other an alkene?
Bromine water is an orange coloured solution of bromine
When bromine water is shaken with an alkane, it remains orange as there no C=C bonds present; so the bromine remains in solution
When bromine water is shaken with an alkene, it decoloursies due to the presence of a C=C bond
The bromine atoms add across the C=C hence the solution no longer contains orange bromine water
What type of reaction occurs between an alkene and bromine water
An addition reaction
Example of an addition reaction
What is addition polymerisation
The joining of monomers to form addition polymers
This only occurs in monomers containing C=C bonds
What occurs in addition polymerisation
One of the bonds in each double bond breaks and forms a bond with the adjacent monomer
An example of an synthesized alkene monomer in poly-ethene
What is a hydrogenation reaction
When an alkene is reacted with H2 to form an alkane
This reaction occurs at 150*C using a nickel catalyst
Practical use of hydrogenation reaction
Turning vegetable oils into margerine for supermarkets
What are the conditions and products of alkene + steam
Conditions - 300*C, 60-70atm, concentrated phosporic acid catalyst
Alkene + water –> alchahol
This is called the hydration of alkene
What is an alchahol
Contains the -OH functional group
What is ethanol
An alchahol - C2H5OH
Found in alchaholic drinks, used in cars as a solvent for fuel
Ethanol burns in excess to form carbon dioxide and water
What are the two methods for the manufacture of ethanol
Hydration of ethene
fermentation of glucose
How is the fermentation of glucose carried out
(ethanol manufacture)
Sugar or starch is added in water and yeast is added
Mixture ferments for a few days with no oxygen between the tempuratures 15 and 35*C
Yeast contains enzymes that break down the starch or sugar to glucose
If the tempurature is too slow the reaction rate will be too low
If the tempurature is too high the enzymes denature
The yeast respires anaerobically to form CO2 and ethanol
The yeast are killed off oncethe level of alchahol is 15%
Balanced equation of fermentation of glucose
Comparison of fermentation to hydration of ethene - hydration of ethene
Hydration of ethene -
complex set up
uses non-renewable resources
fast rate of reaction
produces pure ethanol
No greenhouse gases produced
Reaction conditions - high temp and pressure
Comparison of fermentation and hydration of ethene - fermentation
Simple equipment needed
Uses re-newable resources
Batch proccess - inefficient
Very slow process
Produces a dilute solution of alchahol which requires further processing
What is a carboxylic acid
The homologous series containing the functional group -COOH
Colourless liquid
Weak acids, typical acidic properties
They react with alkaline solutions, turn blue litmus red, and form salts called ethanoates
Properties of ethanoic acid
Weak acid
Dissociates slightly in water
Equilibrium lies far to the left in ionization
ethanoic acid reacts with more reactive metals, carbonates and hydroxides
How to make carboxylic acids - oxidation by fermentation
The microbial fermentation of alchahol will produce a weak solution of vinegar
This occurs when a bottle of wine is opened as the bacteria in the air use the oxygen in the air to oxidise the ethanol in the wine
The acidic, vinegary taste of opened wine is due to the production of ethanoic acid
Production of carboxylic acids - alchahols heated with potassium manganate
Alchahols are heated with potassium mangante in a vessel with a condenser attached to the top
The condenser prevents the volatile alchahol from escaping from the reaction vessel as alchahols have low boiling points
How are esters made
By adding alchahols and carboxylic acids togeth
What are esters
Esters are compounds with the functional group R-COO-R
Esters are sweet smelling oily liquids in food flavourings and perfumes
