3.3.2 - Alkanes Flashcards
(30 cards)
General formula for straight/branched chain alkanes?
CnH2n+2
General formula for cyclic alkanes?
CnH2n
What is the bond angle in straight chain alkanes?
109.5 degrees
Are alkanes polar?
No
Are alkanes soluble?
No
What IMFs are between alkane molecules?
vdWs’ only
How do you get from an alkane to a haloalkane?
Free radical substitution
What carbon chain length in gaseous alkanes?
1-4
What carbon chain length in liquid alkanes?
5-17
What carbon chain length in solid alkanes?
18+
Solid alkanes have a ______ feel to them
Waxy feel
What is fractional distillation?
Separating crude oil into different fractions based on boiling point
What is a fraction?
Hydrocarbon molecules of similar carbon chain lengths and properties
Fractional distillation is a ______ process - why?
Physical process: vdW forces between alkane molecules are overcome in vaporisation and reformed in condensation
Unburnt hydrocarbons can form what? Why is this bad?
Photochemical smog - carcinogenic
Temp of top and bottom of fractionating tower/column?
Top - 400K
Bottom - 630K
What is ‘cracking’?
Breaking C-C bonds in alkanes to produce a mixture of shorter chain alkanes and alkenes that are more economically valuable
Two types of cracking?
Thermal and catalytic
Describe thermal and catalytic cracking
Thermal: 1000degrees C; 70atm; no catalyst
Catalytic: 450degrees C; slight Pa; honeycomb zeolite catalyst
Main products of thermal and catalytic cracking
Thermal: alkenes
Catalytic: cycloalkanes; aromatic compounds; motor fuels; branched alkanes
What are catalytic converters made from?
Platinum and rhodium in a honeycomb structure
What is the aim of flue gas desulfurisation?
To remove SO2 from the combustion of coal
Use of very short chain alkanes?
Camping gas (butane, propane)
Use of gasoline?
Car petrol
