Unit 10 - Organic Chemsitry Flashcards
What is crude oil
Crude oil is a mixture of hydrocarbons
Describe how the industrial processes of fractional distillation separates crude oil into fractions
Because they have different boiling points, the substances in crude oil can be separated using fractional distillation.
The crude oil is evaporated and it’s vapours are allowed to condense a different temperatures in the fractioning column.
Each fraction contains a hydrocarbon molecules with a similar number of carbon atoms
What are the main fractions obtained from crude oil
Refinery gases - bottled gas gasoline - fuel for cars Naphtha - making chemicals kerosene - aircraft fuel diesel - fuel for cars and buses fuel oil - fuel for ships Residue / bitumen - for roads and roofs
Describe the trend in boiling point and viscosity of the main fractionsA
As the boiling point increases so does the viscosity
What is dangerous about the incomplete combustion a fuels
Incomplete combustion of fuels may produce carbon monoxide
CO is poisonous because it reduces the capacity of the blood to carry oxygen
How are nitrogen oxides formed in car engines
The temperature reaches hi enough to allow much and oxygen from the air to react within the car engine
How are the long chain hydrocarbons produced from the residue converted into shorter chain alkanes
The long train hard hydrocarbons are converted into useful alkanes and short-chain alkanes by catalytic cracking, using silica or alumina as the catalyst and a temperature in the range of 600 to 700°C to crack the long chains
What are hydrocarbons
Hydrocarbons are compounds containing hydrogen and carbon only, joined conveniently
What does it mean by a saturated hydrocarbon
Saturated means that all the covalent bond are single bonds
What are Alkanes
Saturated hydrocarbons
General formula C(n)H(2n+2)
What are isomers?
Substances with the same formula but different structure (arrangement of atoms)
How and why do boiling points of alkenes change?
Boiling points increase as you go from one to another as larger molecules have stronger intermolecular forces.
If a molecule is bigger it will have a….
Higher boiling point
What is cracking?
The breaking down of large less useful oil fractions into smaller molecules
What is catalytic cracking?
Cracking with the aid of a catalyst
What is a monomer?
A small molecule which can join with itself to form a large molecules called a polymer
What is addition polymerisation?
A process by which simple alkene molecules link together to form a large molecule with the same empirical formula
Naming polymers after addition polymerisation (probably useful)
Ethene –> polythene
Propene –> polypropene
E.t.c
What are alkenes
Hydrocarbons with a double bond
General formula H(n)C(2n)
What are alkenes
Hydrocarbons with a double bond
General formula C(n)H(2n)
Products of compels combustion of Alkanes
Water and CO2
Products of incomplete combustion of Alkanes
Water and CO
General formula for alkenes
CnH2n
Describe the addition reaction of alkenes with bromine, including the bromine water test for alkenes
An alkene will make its double bond into a single bond, to bond to two bromines. Bromine is added to the molecule. The product made is colourless. When alkenes are put in bromine water it turns from brown to colourless (a good way of testing for alkenes.)
For example:
C2H4(g) + Br2 (aq) → C2H4Br2 (aq)
Describe the manufacture of ethanol (from ethene)
Pass ethene and steam over a phosphoric acid catalyst at a temperature of about 300 degrees and a pressure of about 60-70atm
Evaluate factors relevant to the choice of method you’d use to make ethanol
Fermentation: Cane sugar widely avalible/ cheap/ renewable Slow process Impurities in the product Done in batches
Hydrating (ethene and steam): Crude oil (cracked to make ethene) expensive/ non-renewable Fast process Pure product Continuous reaction
Dehydration of ethanol to ethene using AlO
C2H5OH –> C2H4 + H2O
ethanol –> ethene + water
aluminium oxide is the catalyst for this reaction.
How is an addition polymer formed?
By the joining up of many molecules called monomers
What type of polymer is nylon ?
Nylon is a condensation polymer
