C7- Organic Chemistry Flashcards
What are alkanes
The simplest type of hydrocarbon
Alkanes are a _ series
Homologous
What is a homologous series
a group of organic compounds that react in a similar way
Alkanes are _ compounds
Saturated
What is a saturated compound
Each carbon atom forms four single covalent bonds
What are the first four alkanes
- Methane
- Ethane
- Propane
- Butane
As the length of the carbon chain _ , the properties of the hydrocarbon _
Change
Change
Hydrocarbons with shorter carbon chains are also more …
Volatile
The shorter the carbon chain, the more _ the hydrocarbon is
Flammable
hydrogen + oxygen →
carbon dioxide + water (+energy)
Is crude oil a fossil fuel
Yes
How is crude oil formed
From the remains of plants and animals, mainly plankton, that died millions of years ago and were buried in mud. Over millions of years, with high temperature and pressure, the remains turn into crude oil, which can be drilled up form the rocks where it’s found
What is fractional distillation used for
To separate hydrocarbon fractions
What is crude oil a mixture of
Lots of different hydrocarbons,most of which are alkanes
How does fractional distillation work
- The oil is heated until most of it has turned into gas. The gases enter a fractionating column
- In the column there’s a temperature gradient
- The longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column early on, when they’re near the bottom. The shorter hydrocarbons have lower boiling points. They condense and drain out much later on, near to the top of the column where it’s cooler
- You end up with the crude oil mixture separated out into different fraction. Each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points
What are the uses of crude oil
- Oil provides the fuel for most modern transport
- The petrochemical industry
- All the products you get font crude oil are examples if organic compounds
Are short or long chain compounds hydrocarbons flammable
Short-chain hydrocarbons
How to do cracking (splitting up log-chain hydrocarbons)
- Thermal decomposition reaction - breaking molecules down by heating them
- The first step is to heat long-chain hydrocarbons to vaporise them (turn onto gas)
- Then the vapour is passed over a hot powdered aluminium oxide catalyst
- The long-chain molecules split apart on the surface of the speks of catalyst - this is catalytic cracking
- You can also crack hydrocarbons if you vaporise them, mix them with steam and then heat them to a very high temperature. This is known as steam cracking
What is meant by cracking
Splitting up log-chain hydrocarbons
What kind of bond does alkenes have
C=C double bond
General formula for alkenes=
CnH2n
Alkene + oxygen →
Carbon + Carbon Monoxide + Carbon Dioxide + Water (+energy)
What does incomplete combustion result in
A smoky yellow flame and less energy
Alkenes react via _ reactions
Addition
What is a ‘functional group’
a group of atoms in a molecule that determined bow that molecule typically reacts
Do all alkenes react in a similar way and why
Yes, they all have ‘C=C’
What is addition of hydrogen known as
Hydrogenation
What does steam react with alkenes to form
Alcohols
Do halogens react with alkenes
Yes
What are polymers made of
Lots of the same molecule joined together in one long chain
What are plastics made up of
Long-Chain Molecules called polymers
What is the reaction called to produce polymers
Polymerisation
What kind of bond do monomers that make up addition polymers have
Double covalent bonds
How do you draw the displayed formula of an addition polymer form the displayed formula of its monomer
- start by drawing the two alkene carbons, replace the double bond with single bond and add an extra single bond to each pf the carbons
- Then fill in the rest of the groups in the same way that they surrounded the double bond in the monomer. Finally , stick a pair of brackets around the repeating bit, and put an ‘n’ after it (to show that there are lots of monomers)
How do you get from the displayed formula of the polymer to the displayed formula of the monomer
Do the reverse
What is the general formula of alcohols
CnH2n+1OH
What are properties that the first four alcohols have
- Flammable
- They undergo complete combustion
- Soluble in water. Their solution have a neutral pH
- They react with sodium
- They can be oxidised by reacting with oxygen to produce a carboxylic
Alcohols are used as - and _
Solvents and fuels
Sugar →
ethanol + carbon dioxide
What functional group do carboxylic acids have
COOH
Do carboxylic acids react like other acids
Yes