Chapter 1 - Organic Chemistry Flashcards
Define Organic Chemistry:
Chemistry of compounds that come from crude oil
- What is crude oil?
A finite resource found in rocks
What is crude oil a mixture of? What is it the remains of?
A mixture of a very large number of compounds. It is the remains of an ancient biomass (mainly plankton)
How is crude oil formed?
The biomass gets burned via sediment, which over millions of years gets built up, causing heat & pressure.
What is crude oil a mixture of?
A mixture of hydrocarbons.
What are hydrocarbons?
A hydrocarbon is a molecule made from hydrogen and carbon atoms only.
What is an Alkane and what is it made from?
An alkane is a molecule made from C-C (carbon-carbon) single bonds and C-H (carbon-hydrogen) bonds.
Name the first 4 Alkanes and define their molecular formula:
What is the memory tool you can use to help you?
Methane - CH(4)
Ethane - C(2)H(6)
Propane - C(3)H(8)
Butane - C(4)H(10)
Monkeys
Eat
Peanut
Butter
What does molecular formula show?
The number and types of atom of each element in the molecule, e.g C2H6
What does the displayed formula show?
The relative positions of all the atoms in a molecule and the bonds between them.
What is the general formula of alkanes?
Cn H(2n+2)
Why are alkanes saturated hydrocarbons?
All C-C bonds are single covalent bonds. This means that they contain as many hydrogen atoms as possible in each molecule. No more hydrogen atoms can be added.
Define the homologous series:
A group of organic compounds which have the same functional group.
What is a functional group?
An atom or group that gives organic compounds their chemical properties (all do the same reactions)
What do functional groups show?
They show a gradual variation in physical properties (e.g boiling points) and have similar chemical properties.
What do fractions allow hydrocarbons to do?
The many hydrocarbons in crude oil may be separated into fractions.
Fractions contain…
Molecules with a similar number of carbon atoms, by fractional distillation
Describe the process of fractional distillation in five steps:
1) Crude oil is vaporised
2) Vapour enters the fractionating column
3) Column is hot at bottom (350 degrees) and cold at top (25 degrees)
4) Fractions have different boiling points and condense at their boiling points
5) Heavy fractions collect at the bottom and light fractions collect at the top
What is LPG short for:
Liquid petroleum gas
What are five properties of hydrocarbons at the top of the tower?
1) low boiling points
2) Small chain molecules
3) volatile (turns to gas easily)
4) Flammable
5) Not viscous (how easily they pour)
What are five properties of hydrocarbons at the bottom of the tower?
1) High boiling points
2) Long chain molecules
3) Not volatile
4) Viscous
5) Not very flammable
What colour are long chain hydrocarbons?
They are generally darker
Hydrocarbons with the smallest molecules have what boiling points?
The lowest boiling points
Name the 7 hydrocarbons from top of the tower to bottom in order:
1) LPG
2) petrol
3) paraffin
4) diesel
5) fuel oil
6) lube oil
7) Bitumen
What are the lighter fractions from crude oil useful for? What do they do when they burn?
They are very useful as fuels. When hydrocarbons burn in plenty of air they transfer lots of energy to the surroundings.
What is oxidised during combustion?
The hydrogen and carbon in fuels are oxidised.
Name two ways to prove combustion?
1) calcium chloride paper
- pink (+water) -> blue
2) anhydrous copper sulphate
- white (+water) -> blue
What does complete combustion always result in?
The formation of CO2 and water.
When does incomplete combustion happen?
When there is a limited amount of oxygen.
What does incomplete combustion produce?
Produces CO (carbon monoxide) OR C (Carbon) and H20 (water)
- CH4 + O2 -> CO + H2O
- CH4 + O2 -> C + 2H20
Not balanced equations
Name thee problems with incomplete combustion:
- Carbon monoxide is a toxic gas
- Colourless and odourless gas so not easily detected
- Particulates (soot) cause global warming and health problems
Name the first three Alkanes and their molecular formula:
Ethene - C2H4
Propene - C3H6
Butene - C4H8
What is the general formula for alkenes?
Cn H (2n) - C10H20
Alkenes contain a what bond?
A carbon double bond
Why is cracking used? Why is this?
There is a higher demand for shorter hydrocarbons than longer hydrocarbons.
Shorter hydrocarbons make better fuels (easier to ignite)
What does cracking always form in terms of molecules?
It always forms an alkane and an alkene.
What is the process of cracking?
Liquid paraffin on mineral is in a test tube. This is heated and the liquid boils into gas. This passes over a broken porous pot (catalyst) and into a delivery tube. This delivery tube runs through a tray of water and the gas condenses. The liquid collects in a test tube connected to the delivery tube.
Do you test for alkenes?
Bromine water (turns colourless)
Are Alkenes saturated or unsaturated? What does this mean?
Unsaturated. They have a carbon double bond and so hydrogen (and other molecules) can be added to it.
Are Alkanes saturated or unsaturated? What does this mean?
Saturated. They have a carbon single bond and so hydrogen (and other molecules) cannot be added to it.
Why do Alkenes burn with smokey flames?
Because of incomplete combustion
What is hydrogenation and describe it:
Addition of hydrogen to carbon double bonds reduces the level of unsaturation (makes it more saturated)
What is hydrogenation used for?
Used to harden vegetable oils (increases their melting points) when making margarine
Describe the process of halogenation:
Addition of halogens to carbon double bonds forming a dihaloalkane
Is Halogenation used for?
Can be used as a test for carbon double bonds since bromine is orange but the product is colourless
Hydration is the use of…
Ethanol being widely used as a solvent, fuel, or to make other useful products.
What happens during fermentation? (one line of info)
Aqueous solutions of ethanol are produced when sugar solutions are fermented using yeast.
What is the equation for fermentation?
C6H1206 -> 2CH3CH2OH + 3CO2
