Topic 7 - Organic Chemistry Flashcards
What is a hydrocarbon?
A molecule that is formed only from hydrogen and carbon
What are the first four alkanes?
Methane
Ethane
Propane
Butane
What is the formula for alkanes?
CnH2n+2
What are saturated compounds?
Each carbon atom has four single bonds, no double bonds
What are the properties of alkanes as chin size increases?
Boiling point increases
Volatility decreases due to high boiling point
Flammability decreases
Viscosity increases
What is the formula for complete combustion?
Hydrocarbon + oxygen -> Co2 + water
What is fractional distillation?
The process of separating crude oil into its hydrocarbon components
How is crude oil made?
Plankton that died millions of years ago and got buried.
They got turned into crude oil by high temperatures and pressures
They can be drilled out of the rock
What are the key features of fractional distillation?
A fractional column that is cooler toward the top.
Hydrocarbons will condense into a liquid a certain points when the become cooler than there boiling points
What is cracking?
Cracking is a thermal decomposition reaction which uses heat to break down hydrocarbons
What are the two types of cracking?
Steam cracking
Catalytic cracking
What are the steps to catalytic cracking?
Vaporise the alkanes
Pass over aluminium oxide powder
This causes them to split apart
What are the steps of steam cracking?
Vaporised alkanes
Mix with steam
Heat to high temp so alkanes are split
What is an alkene?
An hydrocarbon with a double bonded carbon
What is the formula for alkenes?
CnH2n
What forms during cracking?
An alkane and an alkene
Are alkenes saturated or unsaturated and why?
Unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
What are the difference between alkanes and alkenes?
Alkenes are more reactive so when added to bromine water it will turn from orange to colourless
Alkenes can be added together to form polymers by breaking their double bond
What is the test for alkenes?
Adding them to bromine water should turn it colourless
What are the three types of addition reactions with alkenes?
Hydrogen
Water
Halogen
Explain the addition reaction with alkenes and hydrogen
Hydrogen and alkene passed over catalyst to from alkane
Explain the addition creation with alkene and water
Ethene and water over catalyst with high temperatures from ethanol
How can you separate water and ethanol
With fractional distillation
Explain the addition reaction with an alkene and a halogen
Ethene and bromine into colourless dibromoethane - an alkane. This is how the test for alkenes takes place.
Do alkenes react with oxygen and how?
Yes, the react with oxygen in combustion reactions but they produce smoky flames due to incomplete combustion.
How can alkenes make polymers?
By addition polymerisation
What is addition polymerisation?
The process in which many small monomers join together right form very large polymers
What functional group does an alcohol contain?
An OH
What is the general formula for an alcohol group?
CnH2n+1OH
What happens when an alcohol reacts in air?
Combustion reaction where alcohol and oxygen form carbon dioxide and water
What happens when an alcohol is added to water?
The alcohol will dissolve into water with and have a neutral pH
What happens when an alcohol reacts with an oxidising agent?
It forms a carboxylic acid
What happens when an alcohol reacts with sodium?
It forms hydrogen and a salt e.g sodium ethoxide
What is condensation polymerisation?
Involves the use of two functional groups and usually loses a small molecule like water
What is needed for condensation polymers?
Each monomer has to have at least two functional groups. And there overall needs to be two different functional groups.
How can ethanol be created by fermentation and what are the necessary conditions?
Fermentation of sugar using yeast cells. Around 30-40 degrees for optimum temperature of enzymes and anaerobic conditions so the thankless isn’t oxidised.
How can ethanol be produced using steam?
Needs a temp of 300c and 60-70 atmospheres pressure over a catalyst. Reacts ethene with steam
What is the functional group for a carboxylic acid and what is the end of the name of a chemical in the series?
COOH and ends in ..anoic acid
What are carboxylic acids weak?
Because they don’t fully ionise.
What happens when a carboxylic acid reacts with a metal carbonate and give an example?
Carboxylic acid + metal carbonate -> salt. + water + carbon dioxide
Ethanoic acid +. Potassium carbonate -> potassium ethanoate + water + carbon dioxide
How are carboxylic acids made?
By reacting an alcohol with an oxidising agent to add thee required oxygen for the functional group
What is the functional group of an ester?
COO
What are the properties of esters?
Easily evaporate, volatile and have pleasant smells
How are esters made and what happens during the reaction?
Reacting a carboxylic acid and an alcohol. The acid loses a PH group. And the alcohol loses a Hydrogen to form a water molecule.
What are three naturally occurring polymers?
Polypeptides, DNA, Carbohydrates
What makes a polypeptide a polymer - how is it made?
The reaction of amino acids by condensation polymerisation. This is because an amino acid contains a carboxylic acid group and a amino group.
What are the monomers of DNA?
Nucleotides
How are carbohydrates a polymer - how are they made?
They are made of monomers which are made of carbon, oxygen and hydrogen. The monomers join together to form polysaccharides.
