1.6 - ALKANES

HideShow resource information
  • Created by: Sophie
  • Created on: 13-05-15 18:40
Preview of 1.6 - ALKANES

First 257 words of the document:

1.6 ALKANES
· Alkanes are saturated hydrocarbons = only contains single C-C bonds.
· General formula: CnH2n+2
· Cycloalkanes ­ when carbon atoms from a ring other than benzene,
formula: CNH2n (same as alkenes because end hydrogens not required)
NON-POLAR INSOLUBLE
·difference in ·they only have vdW
electronegativty forces between
between C and H is molecules so do not
form H-bonds (can
very small disolve in organic
solvents)
UNERACTIVE BOILING POINTS
·C-C and C-H bonds ·increase with chain
length, larger surface
are very strong (still
area, more vdW forces
have 2 reactions:
·decrease with
combustion and brancing, less closely
forming haloalkenes) packed, vdWs less
PROPERTIES effective
Fractional distillation ­ the process by which crude oil is separated into fractions
(similar chain lengths & properties) of different boiling points.
· Crude oil ­ a mixture of hydrocarbon molecules, mainly straight and
branched chain alkanes
3. Vapour moves up
tower via series of
2. Liquid/vapour trays containing
1. Crude oil heated in mixture passes into
bubble caps until it
a furnace tower that is cooler at
reaches tray that
the top
has a lower Tb than
itself
5. Shorter chain
Thick residue that hydrocarbons
collects at the base is 4. Condense to liquid.
condense in trays at Mixture that
tar or bitumen (road
the top because they condenses is piped off
surfacing)
have a low Tb

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Different components are drawn off at different levels in
fractionating column because of temperature gradient
· Fractional distillation is a physical process so no covalent
bonds within the molecules are broken. It's the van der Waals
forces between molecules that are broken during vaporisation
and reform on condensing.…read more

Page 3

Preview of page 3

Page 4

Preview of page 4

Here's a taster:

Combustion
· Shorter chain alkanes burn completely in excess oxygen to form
combustion products CO2 and H2O
E.g.
CH4 2O2 2H2O CO2 EXOTHERMIC
· Combustion reactions give out heat and the more
carbons present, the greater the heat output.
· Makes them good as fuels (which release heat energy when undergone
combustion)
Incomplete combustion
· Combustion in presence of limited oxygen, producing CO or C (soot)
· Usually happens with longer chain hydrocarbons as they need more
oxygen to burn compared with shorter chains
e.g.…read more

Page 5

Preview of page 5

Here's a taster:

Removing sullfur
· Some chimneys used calcium oxide CaO, or limestone CaCO3
to absorb the sulphur dioxide.
· Produces gypsum CaSO4, which is used as a plaster
· FLUE GAS DESULFURISATION
Catalytic converters ­ device fitted to car exhaust containing a catalyst where NOx's
are reduced to N2 and CO, and unburnt hydrocarbons are oxidised to CO2 and hydrocarbons to
H2O
· Sulphur is removed from petrol already so sulphur dioxide is
less of a problem.…read more

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »