Alkane 12 Flashcards
Polarity
Non-polar
Weak intermolecular forces between molecules are weak van der walls forces
Boiling point
Boiling point increases when the chain increases, shorter chains are gases at room temperature
Solid when over 18 carbons
Solubility
Insoluble in water because water molecules are bonded by hydrogen bonding
How alkanes react
Relativity unreactive
Can burn and react with halogens under suitable conditions ( a plentiful oxygen supply)
Fractional distillation of crude oil
Crude oil is first heated in a furnace
Mixture of liquid and vapour passes into a tower that is cooler at the top
Vapours pass up the tower via a series of trays
Condense to liquid
Liquid is pumped off
Bitumen
Road surfacing
Gasoline or petrol
Cars
Kerosene or paraffin
Jet fuel
Diesel oil
Lorries and taxes
Lubricating oil and waves
Candles and engine oil
Fuel oil
Ships
Power stations
Fracking
Gas can be extracted by drilling ibto the shale and forcing pressuried water mixed with sand. This means that the rock breaks up realesing trapped gas.
Natural gas
CH4 + 2O2 —— 2CO2 + 2H2O
Opposition of fracking
Don’t like the infrastructure of wells and the associated traffic
Concerns about the amount of water used
Worried about chemicals added to the water
Can cause small earthquakes
Burning natural gas producing carbon dioxide
Thermal cracking
Heating alkane to a high temperature (700-1200K) and high pressure (7000kPa)
Creates free radical to create small chains (free radicals = highly reactive)
(Thermal cracking takes place at high pressure and high temperature and produces a high percentage of alkenes)
Catalytic cracking
Temperature of 720K
Lower pressure
Zeolite catalyst ( honeycomb structure with a large surface area)
Acidic
Used to produce motor fuels
(Catalytic cracking takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst and is used mainly to produce motor fuels and aromatic hydrocarbons)
Combustion
Burn in a plentiful supply of oxygen
Give out heat ( large negative enthalpies)
More carbon more heat
Incomplete combustion
Limited supply of oxygen
Carbon monoxide is produced
NO
NO2
N2O4
(Nitrogen oxides)
Can happen when in a petrol engine at high temperature. Oxygen reacts with the water vapour
Sulphur dioxide
Acid rain
Sulphur impurity in crude oil
Carbon particles
Can exacerbate asthma and cause cancer
Unburnt hydrocarbon
Photochemical smog
Flue gas desulfurisation
When you burn fossil fuels there are sulphur impurities and sulphur dioxide is produced.
Calcium oxide and water to from calium sulfate which can be oxidised to make gypsum which is used in plaster board.
Or you can use lime stone
Catalytic converter
Honeycomb made of ceramic material coated in platinum and rhodium metals
React to form less harmful gases
Alkanes
Saturated hydrocarbon
Carbon and hydrogen only
Global warming and green house effect
Carbon dioxide behaves like glass, it traps infrared radiation so the earth heats up. Other greenhouse gases such as methane and water vapour.
Carbon neutral activities
Actives such as airline flights produce a large amount of carbon dioxide.
Process in a Chain reaction
Initiation
Propagation
Termination
Initiation
Uv light
Cl2 —- 2Cl.
Two chlorine radicals
Free radicals are highly reactive
Propagation
Cl. + CH4 —— HCl + .CH3
.CH3 + Cl2 ——- CH3Cl + Cl.
Both of the equations create another free radical
Termination
Cl. + Cl. —– Cl2
.CH3 + .CH3 —— C2H6
Cl. + .CH3 —— CH3Cl
Forms no unpaired electrons
Chlorofluorocarbons and ozone layer
Cl. + O3 —- ClO. + O2
ClO. + O3 —– 2O2 + Cl.
2O3 —– 3O2
Cracking
Splitting larger hydrocarbon chains into smaller ones which are more useful
Why is cracking important?
High market demand for smaller hydrocarbon chains
Larger hydrocarbon chains are split
Alkenes and alkanes
Alkenes are more useful than alkanes at starting materials for further chemical reaction
Polluting gases
Soot Water vapour Carbon dioxide Carbon monoxide Unburnt hydrocarbon Nitrogen oxides Sulphur dioxide
Removing sulfur (flue gas desulfurisation)
Power station
Acid rain
Calcium oxide + water
Calcium sulfite (oxides)
Gypsum (used in builders plaster)
CaO + 2H2O + SO2 + 1/2O2 ——— CaSO4.2H2O
CaCO3 + 1/2O2 + SO2 —— CaSO4 + CO2
Catalytic converter
Internal combustion engine
Reduces amount of pollutants ( big surface area)
Honeycomb made of ceramic material coated with platinum and rhodium metals
2CO2 + 2NO —– N2 + 2CO2
Global warming
Visible rays from the sun pass through the carbon dioxide ( traps infrared radiation)
Halogenalkanes
Only react with UV light
So they don’t react in a dark room
Alkanes
Saturated hydrocarbons
Incomplete combustion
C3H8 + 7/2O2 —– 3CO2 + 4H2O
