Checklist C9, C10, C11 - Organic Chemistry Flashcards
What is crude oil?
A mixture of hydrocarbons
What is crude oil formed from?
The remains of ancient biomass (mostly plankton) that was buried in mud
What is a finite resource?
One that will run out
Why is crude oil a finite resource?
It takes longer to form than the rate at which we are using it up
What is a hydrocarbon?
A compound made up of carbon and hydrogen only
What is a general formula?
A mathematical formula which allows you to work out the chemical formula of a substance
What is an alkane?
A hydrocarbon with only single bonds
Name the first four alkanes.
Methane, ethane, propane, butane
What is the general formula for alkanes?
CnH2n+2
How does the boiling point change with the length of an alkane?
The longer the alkane the higher the boiling point
How does the viscosity change with the length of an alkane?
The longer the alkanes, the more viscous (thicker) it is
How does the flammability change with the length of an alkane?
The shorter the alkane, the more flammable it is
What is fractional distillation?
A process used to separate mixtures of substances with different boiling points
What are the steps involved in fractional distillation?
Crude oil is vapourised.
The column is hotter at the bottom and cooler at the top.
The molecules travel up the column and condense at different points depending on their boiling points. Smaller molecules condense at the top, larger molecules at the bottom.
Why is fractional distillation important?
The different fractions have different uses
What is a fuel?
A substance which when reacted with oxygen releases energy
Name fuels we obtain from crude oil.
Petrol, diesel, kerosene, heavy fuel oil, liquid petroleum gases
What other uses are there for products of fractional distillation?
Solvents, lubricants, polymers and detergents
What is combustion?
The reaction of a fuel with oxygen
What are the products of complete combustion?
Carbon dioxide and water
When does incomplete combustion occur?
When there is not enough oxygen present
What is cracking?
The process of breaking down long hydrocarbons into smaller ones.
What are the products of cracking?
Short alkanes and alkenes
Why is cracking important?
Smaller hydrocarbons are more useful than longer ones
What are the two types of cracking?
Catalytic and steam cracking
What are alkenes?
A type of hydrocarbon with a C=C double bond that is more useful than an alkane
What are alkenes used for?
As a starting material to make more useful chemicals
How do you test for an alkene?
React it with bromine water
What is the colour change when an alkene reacts with bromine water?
Turns from orange to colourless
What is the general formula for alkenes?
CnH2n
What does unsaturated mean?
Contains double bonds
What are the first four alkenes?
Ethene, propene, butene, pentene
What are the four reactions of alkenes?
Combustion, with water, with hydrogen, with halogens
How is the combustion of alkenes different to the combustion of alkanes?
Alkenes usually burn by incomplete combustion so burn with a smoky flame
Why are the reactions of alkenes with hydrogen, water and halogens known as ‘addition reactions’?
Because new atoms are being added to the molecule by breaking the double bond
What is the product from the reaction of an alkene with hydrogen?
An alkane
What conditions are necessary in the reaction of alkenes with hydrogen?
Nickel catalyst, 60°C
What is the product from the reaction of an alkene with a halogen?
An alkane with two halogen atoms where the double bond used to be
What is the product of the reaction of an alkene with steam?
An alcohol
What conditions are necessary for the reaction of alkenes with steam?
High temperature, high pressure, catalyst
What is polymerisation?
The process of using small molecules (monomers) to make long chain molecules (polymers)
What monomers are involved in addition polymers?
Alkenes
What do the properties of polymers depend on?
The monomers they are made of and the conditions under which they are made
What is the difference between thermosetting and thermosoftening polymers?
Thermosoftening ones melt when they are heated, thermosetting do not
Why do thermosetting polymers not melt when heated?
They have strong cross-links between the polymer chains
Explain what a homologous series is.
A family of hydrocarbons with similar chemical properties.
Describe what a fraction is and state the uses of fractions.
Each fraction consists of a group of hydrocarbons of similar chain lengths.
Fractions can be used as fuels. Each fraction has different properties due to the length of the carbon chain. Therefore, we can use each fraction for different purposes.
