Class 8, Science, Chapter-3, Lecture-2, Petroleum (Notes)
PETROLEUM:
Petroleum is a dark brown viscous mixture of many hydrocarbons.
Constituent Elements- Hydrogen (H) and Carbon (C)
FORMATION OF PETROLEUM-
The small organisms which got deposited at the bed of the seas millions of year ago converted to petroleum under high pressure, high temperature and catalytic action in the absence of air.
The petroleum rose through porous rocks and got trapped between two impervious rocks to form oil trap.
Fossil fuels are exhaustible natural resources.
Reason:
Fossil fuels require millions of years to form from the dead vegetation and animals that get buried deep inside the Earth. They require high temperature and pressure for their formation, which cannot be provided in the laboratory.
Thus, fossils are limited, and extensive use of fossil fuels will lead to their exhaustion.
FRACTIONAL DISTILLATION:
The separation of components of a mixture by using the difference in the boiling points of the component is called a Fractional Distillation.
- During Fractional Distillation:
The components are collected in order of their decreasing Boiling Point. (Max. B.P- collected first)
Differences Between:
Simple Distillation | Fractional Distillation |
· It is used to separate the components of mixture having only two components. | · It is used to separate components of mixture having various components. |
Fractional Distillation of Petroleum:
- The crude oil is heated to 4000C where all the components except Bitumen, Paraffin, wax and lubricating oil vaporise.
- The temperature in the Fractionating column decreases from 4000C to 3500C to 2500C to 1700C.
- The component having highest boiling point condenses first and is collected. The other components are collected in decreasing order of their boiling point.
- Uncondensed gases escape from the top.
The Fractions of Petroleum:
Petroleum Gas – uncondensed gases
Petrol (Gasoline) -1700C
Kerosene- 2500C
Diesel Oil- 3500
Fuel Oil – 4000C
Lubricating oil
Paraffin wax (non-combustible)
Bitumen
Uses:
- Bitumen– for making road surfaces
- Paraffin Wax –
(i) for making candle wax
(ii) for making Vaseline
(iii) for making waxed paper - Lubricating Oil-
for lubrication. - Fuel Oil- for heating industrial boilers.
- Diesel Oil-
(i) for powering heavy vehicles
(ii) to run water pumps
(iii) to run generators to produce electricity. - Kerosene-
(i) for domestic cooking and lighting
(ii) special grade of kerosene is used as aviation fuel - Petrol- (i) for powering light vehicles
- Petroleum Gas-
for domestic cooking as L.P.G.