Alkanes Flashcards
(28 cards)
What is the general formula for alkanes
CnHn+2
How does the structure of alkanes effect boiling point
Longer chains have stronger intermolecular forces (more van der walls) so have higher bp
Branched chains reduce electron cloud contact as the molecules cannot pack as closely together leading to lower bp
What are the conditions of fractional distillation
350 degrees C in a fractionating column
What are the steps to fractional distillation
The oil is Vaporize
Oil enters fractionating column which is top at top and cool at bottom.
Fractions condense just below their bp and are collected.
What are the conditions for thermal cracking
1000 degrees C
70 atm
What are the conditions for catalytic cracking
Zeolite catalyst
450 degrees
Slightly above atmospheric pressure
What are the typical products of thermal cracking
Primary Alkenes used for polymers
What are the typical products of catalytic cracking
Aromatic Hydrocarbons used for fule
What is the equation for complete combustion of a alkane
CH4(g) + 2O2(g) ➔ CO2(g) + 2H2O(g)
What is the equation for incomplete combustion of a alkane
CH4(g) + 3⁄2O2(g) ➔ CO(g) + 2H2O(g)
What are the environmental impacts of Carbon particulates
soot can accumulate in engines, affecting their efficiency and potentially causing long-term damage.
What are the environmental impacts of Carbon Monoxide
Binds with haemoglobin more effectively than oxygen, inhibiting oxygen transportation within the body.
High concentrations lead to asphyxiation, while lower levels may cause blurred vision, poor coordination, and headaches.
What are the environmental impacts of Carbon Dioxide
As a greenhouse gas, carbon dioxide absorbs and emits infrared radiation back towards Earth, contributing to the greenhouse effect
What are the environmental impacts of unburned hydrocarbons
Some unburnt hydrocarbons are carcinogenic.
Unburnt hydrocarbons react with nitrogen oxides in sunlight to produce photochemical smog. This causes respiratory issues.
What are the environmental impacts of Nitrogen Oxides
Nitrogen oxides contribute to the formation of photochemical smog when they react with unburnt hydrocarbons in the presence of sunlight.
Nitrogen oxides also contribute to the formation of acid rain. When nitrogen dioxide dissolves in water, it forms nitric acid (HNO3), which lowers the pH of rainwater:
2NO2(g) + H2O(l) + 1⁄2O2(g) ➔ 2HNO3(aq)
What are the environmental impacts of Sulfur dioxide
Sulfur dioxide dissolves into clouds and oxidised into sulfuric acid, the main component of acid rain. This damages plants, animals and infrastructure.
What is the catalytic converter used for
installed on vehicle exhausts to reduce pollutants
How does a catalytic converter work
Contain a honeycomb structure coated with catalyst metals such as platinum, rhodium, and palladium.
These metals catalyse the conversion of harmful compounds into less harmful substances as exhaust gases pass through.
Give an example of an equation for the catalytic converter
2CO(g) + 2NO(g) ➔ 2CO2(g) + N2(g)
How does flue gas desulphurisation work
Flue gases are mixed with an alkaline slurry containing calcium oxide or calcium carbonate.
The acidic sulfur dioxide reacts with the calcium compounds to form solid calcium sulfite salts
SO2(g) + CaO(s) + 2H2O(l) ➔ CaSO3(s) + 2H2O(l)
SO2(g) + CaCO3(s) + 2H2O(l) ➔ CaSO3(s) + 2H2O(l) + CO2(g)
This harmless calcium sulfite salt is then removed from the flue gas stream before emission.
what is flue gas desulphurisation used for
in power stations to remove sulfur dioxide from flue gases
What is the name of the reaction that turns alkanes into halogenoalkanes
Free radical substitution
What is the initiation stage of FRS
UV light breaks the halogen up into two free radicals
Cl2 ➔ 2Cl*
What is the first propagation step of FRS
Cl* + CH4 ➔ CH3* + HCl
