organic chemistry Flashcards
volatile
evaporates very easily, eg: petrol
viscosity
a liquid that doesn’t flow easily, ‘thick,’ eg: honey, ketchup, oil
Test for alkenes
Bromine water decolourises from orange.
What is a hydrocarbon?
A compound containing hydrogen and carbon only.
Q: Why is oxygen/ nitrogen a gas at room temperature?
They are small molecules. They have very weak intermolecular forces so less energy is needed to break these weak forces and separate these molecules.
Describe the properties of Diamond (the four C’s- Cut, Clarity, Carat and Colour)
- Each carbon atom forms four covalent bonds
- A tetrahedral shape is formed
- No delocalised electrons so diamond does not conduct heat/ electricity
- Diamond is transparent
- Diamond is extremely hard
- There are no layers
- Diamond is brittle
Describe the properties of graphite
- Each carbon atom forms 3 covalent bonds
- Therefore 1 electron is delocalised and can conduct heat/ electricity
- Graphite is very soft because the forces holding each layer are weak so the layers can slide over which is why it is a good lubricant.
- In the layers are covalent bonds.
Give one use of graphite
pencil lead
Why is graphite a good lubricant?
The forces holding each layer are weak so the layers can slide over.
What is the difference between graphene and graphite?
Graphene is made up of a single layer of carbon atoms whereas graphite is made up of many layers.
Describe the properties of fullerenes.
- They are molecules of carbon atoms with hollow shapes
- Their structures are based on hexagonal rings of carbon atoms joined by covalent bonds
- Some fullerences include rings with five or seven carbon atoms
- very good lubricant
- can be used to strengthen tennis rackets
What is buckminsterfullerene used for?
It is used for drug delivery to target areas of the body.
What are two examples of fullerences?
Buckminsterfullerene and nanotubes.
Describe the properties of buckminsterfullerene
- First fullerene to be discovered
- It molecules are made up of 60 carbon atoms joined together by strong covalent bonds
- Molecules of C60 are spherical
- There are weak intermolecular forces between molecules of buckminsterfullerene. These need little energy to overcome so buckminsterfullerene is slippery and has a low melting point
Uses of nanoparticles and why?
- Because nanoparticles are small, they can give greater coverage so more particles can cover the gaps and will last longer- cosmetics
- Nanoparticles are used in computer components: microchips
- Nanoparticles are used as catalysts as they increase the rate of chemical reactions
How big are nanoparticles?
1nm - 100 nm
homologous series
- have similar properties
- all react in a similar way
homologous series
- have similar properties
- all react in a similar way
general formula of alkanes
CnH2n+2
Key features of alkanes
- saturate compounds: every carbon atom has full single covalent bonds
As the length of the carbon chain increases,
- the boiling point increases
- less volatile
- more viscous (thick and sticky)
- less flammable
What are the main uses of hydrocarbons?
- ## fuel, because they release a lot of energy when they are burned with oxygen
complete combustion (enough oxygen)
hydrocarbon + oxygen –> carbon dioxide + water
hydrocarbon and oxygen are being oxidised
What is the significance of shorter hydrocarbons?
- they have the lowest boiling points making them the most volatile and flammable, makes them great fuels.
using a hydrocarbon as a fuel
combustion
combustion
releases a lot of energy in the process
crude oil
- fossil fuel
- a mixture containing nearly only hydrocarbons
- formed from the remains of dead plants and animals, particularly plankton died billions of years ago. High temperatures and pressures under the ground turned the organic biomass into crude oil. The crude oil was soaked into the rocks and was stored for years.
- finite resource
- extract and use it at the same rate- will run out completely
renewable
Will not run out because it is replenished.
non-renewable
will run out because it is not replenished
Fractional distillation
1, Feed the oil into a chamber until it turns into a vapour
2, Pass the vapour into a fractionating column which has a temperature gradient (hot at the bottom and cold at the top)
3, The gases will rise up the column and as soon as they reach a region with a lower temperature than their boiling point, they will condense into a liquid.
4, The long-chain hydrocarbons have higher boiling points than the short-chain hydrocarbons so will quickly condense into a liquid and be piped out of the column. (eg: bitumen- roads, heavy fuel oil can heating oil, fuel oil, lubricating oil).
5, The shorter-chain hydrocarbons will rise up the column until they reach a cooler temperature until they condense into a liquid.
6, LPG- some remain as a gas
7, Longer chain hydrocarbons can be cracked to produce shorter-chain hydrocarbons