Flashcards in Rouge et Orange Deck (89)
How is an addition polymer formed?
By joining up many small molecules (monomers) which have C=C bonds (alkenes)
- using an initiator and high pressure, many monomers open their double bonds and polymerise to form very long saturated chains (polymers)
What are the uses of poly(ethene) and why? (3)
- light, stretchable polymer
- plastic bags, bottles, containers
What are the uses of poly(propene) and why? (3)
- very tough polymer but flexible and resistant to heat
- kettles, food containers, carpets
What are the uses of poly(chloroethene)? (3)
- insulating electrical cables
Why are addition polymers hard to dispose of? (2)
- inert ( don't react easily) because C-C bonds in polymer chain are very strong so not easily broken
- so takes a long time to biodegrade
What does the haber process manufacture?
In the haber process, where is the nitrogen obtained from?
In the haber process, where is the hydrogen obtained from?
Natural gas or the cracking of hydrocarbons
What are the conditions for the Haber process? (3)
Pressure: 200 atm
Temperature: 450 °C
What is the equation used in the haber process?
N2 + 3H2 ⇌ 2NH3 (+ heat)
What happens to the ammonia released and the unused hydrogen and nitrogen after the haber process has taken place?
- The ammonia is formed as a gas, but cools in the condenser, liquefies, and is then removed
- the unused H2 and N2 are reycled and recirculated
In the haber process, what is the ammonia produced used for?
- to make nitric acid (HNO3)
- to make fertilisers by reacting ammonia with nitric acid to get ammonium nitrate
Why is ammonium nitrate a good fertiliser?
- has nitrogen from two sources, the ammonia and the nitric acid. Plants need nitrogen to make proteins
What are the conditions for cracking in industry? (2)
Catalyst: Silica (SiO2) or Alumina (Al2O3)
What is the issue of supply and demand in fractional distillation which makes cracking necessary?
- fractional distillation of crude oil produces more long chain hydrocarbons than can be used directly and fewer short chain hydrocarbons than are required as short chain hydrocarbons can be used as fuels
- to meet this demand, cracking is necessary to split long chain hydrocarbons into short chain molecules
Cracking is a form of ... decomposition
Cracking is a form of THERMAL decomposition
Cracking is the process of...
splitting long chain hydrocarbons into more useful short chain molecules and alkenes which can be used to make polymers
What does homologous series mean?
a group of compounds that can all be represented by the same general formula
What does hydrocarbon mean?
molecules which are made up of hydrogen and carbon atoms only
What does saturated mean?
- a chemical compound that has a chain of C-C bonds. All bonds are already formed.
- alkanes are saturated hydrocarbons.
What does unsaturated mean?
- a chemical compound that has a chain of C=C bonds. The double bond can open up and they can make more bonds.
- alkenes are saturated hydrocarbons.
What is an isomer?
Isomers are molecules that have the same molecular formula, but have a different structure.
SAME MOLECULAR FORMULA
What is the general formula of alkenes?
What is the general formula of alkanes?
What is the formula of methane?
What is the formula of ethane?
What is the formula of propane?
What is the formula of butane?
What is the formula of pentane?