Alkanes Flashcards
Are alkanes saturated or unsaturated?
Saturated
What does saturated mean?
Contains no double bonds.
What is petroleum?
Crude oil - a mixture of different length hydrocarbons.
Is the fractioning column cooler towards the top or bottom?
Cooler towards the top.
What length hydrocarbons exit the column at the top?
Shortest.
Why do short chain hydrocarbons exit at the top?
They have a lower boiling point.
What are the uses for gases?
*liquefied petroleum gas (LPG)
*camping gas
What is the use for petrol (gasoline)?
Petrol in vehicles.
What is the use for naptha?
Processed to make petrochemicals.
What are the uses for kerosene (paraffin)?
*jet fuels
*petrochemicals
*central heating fuel
What are the uses for diesel oil?
*diesel fuel
*central heating fuel
What is the use for mineral oil?
Lubricating oil.
What are the uses for bitumen?
*roofing
*road surfacing
What is cracking?
Breaking longer chain alkanes into shorter chain hydrocarbons.
What are the conditions in thermal cracking?
*high temperature (1000°C)
*high pressure (70atm)
What are the main products of thermal cracking?
Alkenes.
What are the products of thermal cracking used for?
Making polymers (plastics).
What are the conditions in catalytic cracking?
*high temperature (450°C)
*slight pressure
*zeolite catalyst
What are the main products of catalytic cracking?
*aromatic hydrocarbons
*motor fuels
What does the catalyst in catalytic cracking enable?
*lower pressure and temperature
*lower cost
*faster reaction
Why are alkanes good fuels?
Most burn readily and produce large amounts of energy.
What are the products of complete combustion?
Carbon dioxide and water.
What are the products of incomplete combustion?
*carbon monoxide (+ water)
*carbon monoxide and carbon dioxide (+ water)
*carbon/soot (+water)
How does a catalytic converter remove carbon monoxide?
It reacts it with oxygen to make carbon dioxide (less harmful).
Describe the greenhouse effect.
Carbon dioxide (and other greenhouse gases) absorbs infra red radiation from the sun and emit some of it back to earth, making it warmer.
How are oxides of nitrogen produced?
High pressures and temperatures in the engine cause nitrogen and oxygen from the air to react together.
How do nitrogen oxides increase smog?
Hydrocarbons and nitrogen oxides react in sunlight, forming ground-level ozone (O3), which is a major component of smog.
What problems does ground-level ozone cause?
*irritates eyes
*aggrevates respiratory problems
*causes lung damage
How is acid rain formed?
*sulfur reacts with oxygen to form sulfur dioxide when fossil fuels burnt
*rises into the atmosphere and combines with water vapor to form sulfuric acid
*also happens with nitrogen oxides, which form nitric acid
What problems does acid rain cause?
*damages vegetation
*kills aquatic life
*erodes limestone builidings
What does a catalytic converter do?
Reduce the emissions of unburnt hydrocarbons and nitrogen oxides into the atmosphere.
What is wet scrubbing?
Using an alkali to neutralise sulfur dioxide in flue gases.
How is sulfur dioxide removed from flue gases?
*calcium carbonate/oxide is dissolved in water to from alkaline slurry
*spayed on flue gases
*sulfur dioxide reacts with calcium compounds and forms calcium sulphite
What are the steps involved in free radical substitution?
*initiation
*propagation
*termination
