Introduction to Organic Chemistry and Alkanes Flashcards
What is the empirical formula?
The simplest whole number ratio of atoms in a compound or molecule
What is the molecular formula?
The actual number of atoms in a molecule or element
What is the general formula?
i.e alkanes = CnH2n+2
alkenes= CnH2n
alcohols= CnH2n + 1 OH
What is the structural formula?
The arrangement of atoms in a molecule without showing all the bonds (CH3 CH2 CH2 CH2 OH)
What does the skeletal formula show?
The bonds of the carbon skeleton only. Hydrogen and carbon atoms aren’t shown, but functional groups are.
What does the displayed formula show?
The arrangement of atoms and shows all the bonds and atoms in a molecule
What is a homologous series?
A group of compounds that has the same functional group and the same general formula.
What is a functional group?
an atom or group of atoms within a molecule that has similar chemical properties
What are structural isomers?
Molecules that have the same molecular formula, but a different arrangement of atoms in space.
What are the 3 types of structural isomer?
Chain, positional, functional group
What is a chain isomer?
A molecule that has the same molecular formula, but a different arrangement of carbon atoms i.e is branched.
What is a positional isomer?
A molecule that has the same molecular formula, but a different position of the functional group
What is a functional group isomer?
A molecule that has the same molecular formula, but a different functional group
What is the functional group isomer of an aldehyde?
A ketone
What is the functional group isomer of a ketone?
An aldehyde
Where is the carbonyl group located in an aldehyde?
At the end of the molecule
Where is the carbonyl group located in a ketone?
In the middle of the molecule
What is the functional group isomer of an alcohol?
An ether
What is the functional group isomer of a carboxylic acid?
An ester
Give 3 examples of an ester?
Ethyl ethanoate , methyl propanoate, propyl methanoate
Give an example of an ether
1-ethoxy ethane
Stereoisomerism
chem vid
What is the general formula of an alkene?
CnH2n
Are alkanes and cycloalkanes saturated hydrocarbons?
Yes
What 3 ways are alkane fuels formed?
Through the fractional distillation, cracking and reforming of crude oil
What is the functional group isomer of an alkene?
A cycloalkane
What is reforming?
the processing of straight-chain hydrocarbons into branched-chain alkanes and cyclic hydrocarbons for efficient combustion.
Describe the process of fractional distillation?
1) The crude oil is vaporised in a blast furnace at about 350 degrees celcius.
2) The vaporised crude oil enters the fractioning column and rises. The longer chained hydrocarbons don’t vaporise and just run to the bottom.
3) The fractioning column has a temperature gradient, it’s cooler at the top and hotter at the bottom. As each hydrocarbon has a different boiling point, they will each cool and condense at different temperatures.
4) The hydrocarbons with the lowest boiling points don’t condense. They’re drawn off as gases at the top of the column.
What is an addition reaction?
Where 2 or more molecules are joined together to form a larger molecule
What is a polymerisation reaction?
Where lots of simple molecules are joined together to form a giant molecule
What is an elimination reaction?
Where a small group of atoms breaks away from a larger molecule
What is a substitution reaction?
Where one species is replaced by another species
What is a hydrolysis reaction?
Where a molecule is split into 2 new molecules by adding water
What is an oxidation reaction?
Where a species loses electrons in a reaction
What is a reduction reaction?
Where a species gains electrons in a reaction
Nucleophiles ……
contain a lone pair of electrons and are attracted to areas of positive charge
Electrophiles….
are electron deficient and so are attracted to areas of high electron density
Radicals….
have an unpaired electron ad are very reactive and so basically react with anything
What is gas used for?
Liquified petroleum gas (LPG) and camping gas
What is petrol used for?
What is Naptha used for?
What is Kerosene(parrafin) used for?
What is gas oil (diesel) used for?
What is mineral oil (Lubricating) used for?
What’s in greater demand- heavier fractions or lighter fractions?
Lighter fractios
What is cracking?
Breaking long chained hydrocarbons (alkanes) into shorter chained hydrocarbons (alkenes and alkanes) . It involves breaking a C-C bond
What are the 2 type of cracking?
Thermal cracking and catalytic cracking
What temperature and pressure does thermal cracking take place at?
- At high temperatures of up to 1000 degrees Celsius
- At a high pressure of up to 70 atm
What are the main products of thermal cracking?
Alkenes and hydrogen (which can be used in the haber process)
What can the alkenes produced by thermal cracking be used to make?
Polymers (plastics)
What conditions are needed for catalytic cracking?
- a zeolite catalyst
- a slight pressure
- a high temperature of around 450 degrees celcius
What compounds does catalytic cracking mostly produce?
Aromatic hydrocarbons, cyclic alkanes, branched alkanes, motor fuels
What are aromatic hydrocarbons?
compounds containing benzene rings. benzene rings contain a ring of 6 carbon atoms with a delocalised ring of electrons
How can you convert straight chained hydrocarbons into branched alkanes and cyclic hydrocarbons?
By reforming via the use of a catalyst. Hydrogen is produced as the by product of the reactions
What conditions are needed for reforming?
high pressure and high temperature in the presence of a platinum catalyst
Why does reforming hydrocarbons allow for more efficient combustion?
-Because reformed hydrocarbons have lower boiling points and so combust easier and quicker
-Reforming hydrocarbons also reduces the knocking effect, which is where alkanes explode when the fuel or air mixture in the engine is compressed.
Which pollutants are formed during the combustion of alkane fuels?
- Carbon Monoxide
- Oxides of Nitrogen
- Oxides of Sulfur
- Carbon particulates
- Unburned hydrocarbons
What happens when you burn alkanes with oxygen?
you get carbon dioxide and water
What is the possible combination of products when incomplete combustion occurs?
- Carbon monoxide, water, carbon, carbon dioxide
Why is carbon monoxide toxic?
Because the carbon monoxide binds to the haemoglobin in our blood and makes it difficult for oxygen to be transported around the body
How can carbon monoxide be removed?
By using a catalytic converter
Why are oxides of nitrogen formed?
Due to the high temperatures and pressures in the car engine
What happens when nitrogen oxides react with water?
nitric acid can be produced, which can then fall as acid rain
How is sulfur dioxide produced?
By burning fuels with sulfur impurities
What happens when sulfur dioxide is produced?
It reacts with water to form sulfuric acid and this then falls as acid rain
What problems does acid rain cause?
- Destroys plants
- Corrodes buildings and statues
- Kills fish and aquatic life living in bodies of water