C7 - Organic Chemistry Flashcards
What is a hydrocarbon?
A compound that only contains carbon and hydrogen
What are the first 4 alkanes?
- Methane (CH4)
- Ethane (C2H6)
- Propane (C3H8)
- Butane (C4H10)
What are homologous series?
A group of organic compounds that all have similar properties so they react in a similar way
What is the formula for alkanes?
CnH2n+2
What is a saturated compound?
Every carbon atom has 4 single covalent bonds - no double bonds
What happens to the boiling point of alkanes as the chain length increases?
The boiling points increases
Are shorter alkanes more volatile or less volatile then longer alkanes?
The shorter the alkane the more volatile it is (evaporates more easily)
Are shorter alkanes more flammable or less flammable then longer alkanes?
The shorter the alkane the more flammable they are
What does complete combustion require?
It only takes place when enough oxygen is available
What does complete combustion produce?
Carbon dioxide + water and releases loads of energy in the process
How is crude oil produced?
From the remains of dead plants and animals (specifically plankton) and are buried in the mud for millions of years - the high pressures and temperatures form the biomass into crude oil
What process do we use to separate crude oil?
Fractional distillation
How does fractional distillation work?
The crude oil is heated into a gas and passed through a fractionating column. As the gas rises, when they reach a point that is colder then their boiling point they condense into a liquid. The hydrocarbons with the longest chains condense the quickest as they have the highest boiling point
What is cracking?
The process of breaking down large hydrocarbon molecules into smaller ones by heating them in the presence of a catalyst
What is catalytic cracking?
It is when you pass hydrocarbons (in the form of gases) over hot powdered aluminium oxide (catalyst) as the long hydrocarbons come in contact with the catalyst they split apart into two smaller hydrocarbons
What is steam cracking?
Once we have hydrocarbons in the form of vapour we mix them with steam and heat them to a high temperature, this causes the long chain hydrocarbons to split apart into smaller hydrocarbons
What’s the difference between alkanes and alkenes?
Alkenes have a double bond while alkanes don’t. Alkenes are unsaturated while alkanes are saturated
What happens if you add bromine water into a solution of alkenes?
They will decolourise the bromine water from orange to colourless
What can alkenes be added together to make?
Polymers
What type of reaction is cracking?
Thermal decomposition reaction - because it involves using heat to break something apart
The double bond in alkenes make them less or more reactive then alkanes?
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