C7: Organic Chemistry Flashcards
What is a hydrocarbon? [2]:
- Hydrocarbons are molecules made up of only hydrogen and carbon atoms.
- Hydrocarbons differ in their size, which can change the properties of the hydrocarbon.
Crude oil [4]:
- Crude oil is a mixture of lots of different compounds that are not chemically combined.
- Most of the compounds in crude oil are hydrocarbons.
- It is a non-renewable/ finite resource
- It is found in rocks and is used to produce other important chemicals
How is crude oil formed?
From compressing the fossilised remains of ancient plankton
What can crude oil be used to produce? [2]:
- Fuels
- Tarmac
Properties of long chain hydrocarbons [3]:
- Higher boiling points
- High viscosity (very viscous)
- They are less flammable
What is the general formula of alkanes?
CₙH₂ₙ₊₂
Properties of alkanes [5]:
- They are quite unreactive but they burn well
- They make good fuels
- Do NOT readily react with hydrogen water or the halogens
- No reaction with bromine water
- General formula CₙH₂ₙ₊₂
What are the 4 smallest alkanes?
- Methane
- Ethane
- Propane
- Butane
Fractional distillation in organic chemistry
[2]:
- The process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms
(Long chain hydrocarbons into smaller ones) - We call these groups of hydrocarbons “fractions”
How does fractional distillation work?
Fractional distillation separates hydrocarbons using their different boiling points
Distillation process [5]:
- Crude oil is heated until it evaporates
- Crude oil vapour is put into a fractionating column from the bottom and rises upwards
- Long chain hydrocarbons condense at the bottom and are collected as liquids
- Short chain hydrocarbon have lower boiling points and so condense at lower temperatures near the top of the column
- The fractions are collected and processed to create end products
Products of fractional distillation [4]:
- Solvents
- Lubricants
- Polymers
- Detergents
What is the general formula of alkenes?
CₙH₂ₙ
The equation for the complete combustion of alkanes:
alkane + oxygen = carbon dioxide + water
What are 3 properties of Carbon Monoxide?
- Colourless
- Odourless
- Toxic
Burning hydrocarbons with oxygen [2]:
The combustion (burning) of hydrocarbons when there is a good air supply involve: -Energy release and the oxidation of carbon and hydrogen to create carbon dioxide and water
Burning Alkanes with lack of oxygen:
If alkanes are burned without enough oxygen, then carbon
monoxide can be created
Reactivity of alkenes [2]:
- Alkenes are more reactive than alkanes
- Alkenes react with orange-brown bromine water and turn it colourless
The demand for short-chain hydrocarbons [3]:
- There is a large supply of longer hydrocarbons
- However, there is a higher demand for small chain hydrocarbons because they have more uses
- Cracking helps to satisfy this demand
What are the products of cracking? [2]:
- Alkanes
- Alkenes
How can you test for Alkenes?
- Put them in orange-brown bromine water.
- If alkenes are present then the bromine water will become colourless
Cracking [definition]:
Breaking down long hydrocarbon chains into smaller more useful chains
Name two methods of cracking:
- Steam cracking
- Catalytic cracking
Catalytic cracking [2]:
- Vaporised hydrocarbons are passed over a hot catalyst
- The products include alkanes and alkenes