3.3.2 Alkanes Flashcards
Fractions definition
A mixture of chemicals in the crude oil that have similar boiling point
What is the main constituent of crude oil
Alkanes
Are alkanes saturated or unsaturated
Saturated
What is petroleum
A mixture consisting mainly of alkane
hydrocarbons that can be separated by fractional
distillation
What is cracking
Breaking the C - C bond in an alkane
Two types of cracking
Thermal
Catalytic
Thermal cracking conditions
High pressure
High temperatures
Produces high percentage of alkanes
Catalytic cracking conditions
Slight pressure
High temperature
Zeolite catalyst
Produces motor fuels and aromatic compounds
Fractional distillation steps
- Crude oil is vaporised and passed through fractional distillation column
- Vapours rise, cool and condense
- Vapours separated by different boiling points
What are alkanes used for
Fuels
Complete combustion of ethane
C2H6 + 7/2 O2 –> 2 CO2 + 3 H2O
Products of an internal combustion engine
NO, NO2, CO, C, Unburned hydrocarbons
How to remove gaseous pollutants from internal combustion engines
Catalytic converters
Combustion of hydrocarbons with sulfur impurities
Produces SO2, leads to acid rain
Flue gas desulfurisation (2 equations)
SO2 + CaCO3 + 1/2 O2 –> CaSO4 + CO2
SO2 + CaO +–> CaSO3
2 CaSO3 + O2 –> 2CaSO4
Methane + Chlorine
Cl2 –> 2Cl*
CH4 + Cl* –> CH3* + HCl
CH3* + Cl2 –> CH3Cl + Cl*
Cl* + Cl* –> Cl2 / CH3* + CH3* –> C2H6
3 steps to halogenation of alkanes
- Initiation
- Propagation (2 steps)
- termination
Problems of SO2
Acid rain
Can’t be removed by a catalytic convertor
Respiratory problems
Problems of NO2
Acid Rain
Respiratory problems
Problems of CO
Odourless, colourless toxic gas
Binds to Hameoglobin
Problems of C
Respiratory problems
Global dimminng
