3 - Organic Chemistry Flashcards
What are hydrocarbons?
Chains of carbon and hydrogen atoms only
What is an alkane?
Saturated hydrocarbons (only one carbon - carbon bond)
CnH2n+2
Methane, ethane, propane, butane, pentane
What does saturated mean?
That no more atoms can join onto the carbon atoms as all their bonds are already used
What is a homologous series?
A group of compounds:
- That can all be represented by the same general formula
- Similar chemical properties
- Gradation in physical properties
- Families of organic compounds
What is a homologous series?
A group of compounds:
- That can all be represented by the same general formula
- Similar chemical properties
- Gradation in physical properties
- Families of organic compounds
What is the equation for complete combustion?
alkane + oxygen –> carbon dioxide + water (+ energy)
What is the equation for incomplete combustion?
alkane + oxygen –> carbon + carbon monoxide + carbon dioxide + water (+energy)
What happens when a halogen reacts with an alkane?
- Must be in the presence of UV light
- Makes a haloalkane
- Substitution reaction
What is an alkene?
- Hydrocarbons with a double bond between the carbon atoms
- Unsaturated because they can make more bonds (double bone opens up)
- CnH2n
What is an isomer? Give an example
- Two molecules that have identical molecular formulas but different structures
- Butene
What happens when a halogen reacts with an alkene?
- Makes haloalkanes (double bond opens up)
- Bromine + ethane –> dibromoethane
- Addition reaction
How can you test for alkenes?
- Shake an alkene in orange bromine water
- Turns colourless because the bromine molecules react with the alkene to make a dibromoalkane
How can you test for alkenes?
- Shake an alkene in orange bromine water
- Turns colourless because the bromine molecules react with the alkene to make a dibromoalkane
How can you make ethanol?
- Ethene (from crude oil) reacts with steam to make ethanol
- Temperature = 570*C
- Pressure = 60 - 70 atmospheres
- Catalyst = phosphoric acid
- Cheap and not much is wasted
- It will become expensive as crude oil is non-renewable
How can you make ethanol by fermentation?
- Raw material = sugar (e.g. glucose)
- Converted into ethanol using yeast
- Temperature = 30*C
- All renewable resources
- Not very concentrated so needs to be distilled to increase strength
- Needs to be purified
What are the advantages/disadvantages of making ethanol with ethane and steam?
- Fast reaction
- Pure product
- Raw material = ethane (a finite material)
- Expensive equipment
- Low labour cost
What are the advantages/disadvantages of making ethanol through fermentation?
- Slow reaction
- Very impure product
- Raw material = sugar (renewable source)
- Cheap equipment
- High labour cost
How can you make ethane from ethanol?
- Dehydration
- Ethanol vapour is passed over a hot catalyst
- Catalyst = aluminium oxide (Al2O3)
How can you make ethane from ethanol?
- Dehydration
- Ethanol vapour is passed over a hot catalyst
- Catalyst = aluminium oxide (Al2O3)
What is addition polymerisation?
- Monomer alkenes opening their bonds to form a saturated alkane
- Needs a high pressure and catalyst
What is condensation polymerisation?
- Involves two different types of monomers
- The monomers react together and form bonds between them to make polymer chains
- For each new bond a small molecule is lost
- e.g. nylon
What are the uses for polyethene?
- Light, stretchable polymer so ideal for packaging
- Makes plastic bags, bottles and other containers
What are the uses for polypropene?
Tough but flexible and resistant to heat so used for kettles, food containers and carpets
What are some uses for polychloroethene?
Used to make clothes and pips for insulating electrical cables
