Alkanes Flashcards
(20 cards)
Alkanes
CnH2n+2
Fractional distillation
Crude oil is vaporised
Then rises in Columb
Crude oil is a mixture of alkens that very in length = BP
Different alkanes condense at different bps - so condense at different levels
Fractions are pumped separately
Bigger alkanes
Smaller alkanes
Higher bp - more vdw
lower bp
What is cracking
Breaking down a long chain alkane into shorter alkenes
Smaller chains : very volatile
Flammability High
Flow easily
Why does need cracking
More useful products
More In demand
More money
Two types of cracking
Thermal and catalystic
Catalytic crackung
450° temp ( high)
Catalyst- zeoliite
Form aromatic compounds
Thermal cracking
High temperature (~1000°c)
High pressure
Makes alkenes
What are the products of complete combustion
CO2 +H20
In complete combustion
And what do they cause
Co - toxic
C - global dimming
How is so2 made
Complete combustion with a compound with sulfur
CH3SH + 2O2> Co2 + 2H20 +SO2
S +O2 > so2 oxidised
What does SO2 cause and how is it removed give the equation
SO2 causes acid rain
Respitory problems
Removed by flue gas desulphurisation
CaO +SO2 > CaSO3 +O2> Caso4
What’s is used for flue gas desulpurisation and why
And what is made form the process
CaO used
It is basic and we get a neutralisation reaction with so2
Give us plastering
How is nox made
Give equation
Engine +high temp and pressure
Causing the nitrogen in the air to react with O2
N2 + O2 > 2NO
2NO +O2 > 2No2
What does 2No and 2No2 cause
Acid rain toxi and respiratory problems
How us No removed
Via catalytic converter
How does a catalytic converter work
Uses platinum = catalyst on mesh
We have a mesh aswell
Why does catalystic converter use mesh and catalyst
Mesh > large S.A
Catalyst > removes exhaust gases
Give the equations for catalystic converters to remove No
N2 +O2>2N0
2NO+2CO>N2+CO2
Describe how global warming occurs
Short wave length from sun
Enters atmosphere some reflected off
Earth reemmittes rays as long wave length and it is absorbed by atmosphere so its trapped
Increase in global warming
Co2 prevents it from leaving
