Wednesday, May 11, 2011

5.9 I can describe the trend in boiling point and viscosity of the main fractions



3 minutes 4 Seconds

a.       What is the trend in boiling point of the fractions? - As you go up the fractionating column the boiling point decreases 
b.      Define viscosity (source your definition)  - Resistance of a liquid to shear forces (and hence to flow) or the thickness of a liquid 
c.       What is the trend in viscosity of the fractions? - The higher the boiling point the greater the viscosity 
d.      What is the trend in colour of the fractions? - The higher the boiling point the darker the colour


e.      Why is crude oil separated into fractions? - Because each fraction has a different use whilst Crude oil unseparated is virtually useless
f.        What process is used to separate crude oil into fractions? - Fractional Distillation 


g.       What physical property allows this process to work? -  Boiling point


Description: Machine generated alternative text: small molecules
crude oil
is heated
and enters
as a vapour
.
o
0
I petroleum
gases
(such as propane
and butane)
petrol
(gasoline)
• low boiling point (volatile)
. light in colour
easy to light and
bum weU (flammable)
. runny
large molecules
. high boiling point
. dark in colour
. hard to light
• viscous or thick
(if still a liquid at
room temperature
— bitumen is a solid)
low
temperature
I
(paraffin)
kerosine
diesel
lubricating
oil
I heavy fuel
oil
high
temperature
360C
I
bitumen
Image taken from Chem 4 You pg 144

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