Alkanes Flashcards
(29 cards)
Why do branched carbon chains have lower melting points that unbranched chains?
They cannot be packed together as closely, so the intermolecular forces are not as effective.
What liquids do alkanes mix with?
Other relatively non-polar liquids.
What do alkanes not react with?
Acids, bases, oxidising agents and reducing agents.
What do alkanes react with?
They burn in a plentiful supply of oxygen to form CO2 and H2O.
They react with halogens under the right conditions.
Explain fractional distillation.
Used to convert crude oil into useful products by heating the mixture and collecting the fractions that boil over different ranges of temperatures.
This separates the mixture.
When is incomplete combustion most likely to occur?
When burning longer chain hydrocarbons, which require more oxygen to burn.
Why are nitrogen oxides sometimes produced in petrol engines?
If there is enough energy for N2 and O2 in the air to combine.
Why are nitrogen oxides pollutants?
They can react with oxygen and water vapour to form nitric acid, which is acid rain.
They also cause photochemical smog.
Sulfur dioxide can combine with water and oxygen to form sulfuric acid which is acid rain, why is this produced during industrial cracking?
Crude oil contains sulfur impurities.
What are the 2 main greenhouse gases made when hydrocarbons are burnt which were already necessary in the atmosphere?
Water vapour
Carbon dioxide
Why are alkane almost non-polar?
The Electronegativity of carbon and hydrogen are very similar.
What are Alkenes used for in industries?
Alkenes are converted into polymers and products like paints and drugs.
What conditions are required for thermal cracking?
Temperature - 700-1200K
Pressure - up to 7000kPa
What are the conditions for catalytic cracking?
Temperature - 720K
Pressure - low, more than atmospheric
Using a zeolite catalyst
Name a method of flue gas desulphurisation which produced Calcium Sulfite.
Calcium Oxide and water is sprayed into the flue gas.
Further oxidisation of Calcium Sulfite during flue gas desulphurisation can produce Calcium Sulphate, what is an alternative name for this product and what can it be used for?
Gypsum
Saleable product used to make builders’ plaster and plasterboard.
Other than using Calcium Oxide, what is an alternative method of flue gas desulphurisation?
Calcium carbonate instead of Calcium oxide.
What substances do catalytic converters reduce the output of in the exhaust gas of cars.
Carbon monoxide
Nitrogen oxides
Unburnt hydrocarbons
What shape is a catalytic converter and why is this good?
Honeycomb, larger surface area.
What are catalytic converters made out of?
Ceramic material coated with platinum and rhodium metals.
What do greenhouse gases do?
Trap infrared radiation so the Earth’s atmosphere heats up.
What do clouds do?
Reflect solar radiation.
What 3 substances can be used for flue gas desulphurisation?
Calcium oxide
Calcium hydroxide
Calcium carbonate
What is the least popular substance used in flue gas desulphurisation and why?
Calcium carbonate
It produces more CO2, which increases the fine the power station has to pay.
