Thursday, May 29, 2008
@ 6:33 PM
hi everybody...brian here...1st time posting...i guess today's chem was quite cmi, so i shall jot down some of the things we learnt today for those who didn't come or didn't pay attention...i will also be adding stuff from the textbk also... Chemistry Chapter 20: Fuels and Crude Oil
A fuel is a substance that is burnt to produce heat energy (Unimportant...jus nid to noe oni)
1. Uses of fuels:
-> Provide energy for vehicles
-> Produce heat
-> Generate Electricity
2. Sources of fuels are petroleum and natural gas. Fossil fuels include coal, petroleum and natural gas (methane) which are the remains of living plants and animals.
3. These fuels are usually found deep in the seabed as the region under the seabed experiences higher pressure and the sand retains more heat, which causes the remains of dead animals to petroleum and natural gas. These fuels are also extracted by drilling an oil rig into the seabed.
This is an example of an oil rig, a real one...Ms hani said that there is high pay for the people working there, but the risk is big as if there were any accidents to have occured, there would be very little help and assistance would take a long time to arrive, plus, u dun get to go home for mths...
4. Petroleum and natural gas are hydrocarbons - made up of carbon and hydrogens only.
5. Natural gas contain mainly methane.
6. Crude oils are a mixture of hydrocarbons. They are seperated into different oils by using fractional distillation. They have different uses and different boiling points. These oils are insoluble in water and burn in air.
7. Alright, this at my right is a fractional distillation for crude 
oils, and u will need to remeber all the 7 oils and in the correct order...here's a way to rmbr the oils (in order): BLDKNPP
Petroleum gas
Petrol (gasoline)
Naptha
Parrafin (Kerosene)
Diesel
Lubricating oils
Bitumen
* It reads from the lowest to the highest. Jiayou in remebering.
8. Problems of fossil fuels:
-> There are limited amounts of fossil fuels on Earth and cannot be replaced.
-> Coal Burns and produces a lot of ash and sulphur dioxide which causes air pollution and is expensive to be converted into liquid and gaseous fuels.
-> It is important to conserve energy from fuels because they are needed to make plastic, drugs and other chemicals.
Alternative fuels:
-> Palm oil alternative for diesel
-> Hydrogen gas
-> Water
-> Solar energy
Here is the next chapter, Organic Chemistry!
Alright Organic compounds can be classified into 2 different families:
~ Homologous Series*
~ Functional Group*
Homologous Series
1. A general formula
Each member differ to the next one by a CH2. It means they have one carbon and 2 hydrogen atoms more than the previous members.
2. Similar chemical properties
Members of the same group can be made by similar methods and have the same similar reactions.
3. Members of each group shows a steady change in physical properties (such as boiling point) as a result of the increase in the size of the olecules.
More carbon - higher boiling point.
Examples:
C2H4 will have a higher boiling point than CH2
C2H6 will have a higher boiling point than CH4
Bitumen has a higher boiling point than petrol
Functional Group
Each organic family has its own reactive atoms that determines the chemistry of the organic member. These groups of atoms is called funtional group.
Compounds with the same functional group have similar chemical properties.
Homologous Series : Functional Group
1. Alkanes : No functional Group
2. Alkenes : C=C (double bond between 2 carbons)
3. Alcohol : -OH (Hydroxyl Group)
Chain length
->Refers to the number of carbon atoms in an organic molecule
->Chain length will affect the physical properties of the compounds.
->If the chain length is longer, the boiling point and melting point will increase and the density will be higher. If the chain length is shorter, the boiling point and melting point will decrease and the density will be lower.
Examples of Alkanes are:
Methane, CH4
Ethane, C2H6
Propane, C3H8
Butane, C4H10
Pentane,C5H12
Examples of Alkenes are:
Ethene, C2H4
Propene, C3H6
Butene, C4H8
Pentene, C5H10
Examples of Alcohol:
Methanol, CH3OH
Ethanol, C2H5OH
Propanol, C3H7OH
Butanol, C4H9OH
Pentanol, C5H9OH
Similarities:
Each member differ by a CH2 group
Differences:
Each homologous series have a different functional group and general formula.
Number of carbon atoms : Name will start with
One : Meth
Two : Eth
Three: Prop
Four : But
Five : Pent
(there are still somemore, but ms hani said that o'lvls will only come out till the fifth term...i tink)
Alright, shall end here. This post might only benefit those who didn't come or those who went for art halfway cos i jus copied almost everything from the notes. But, i still hope u guys like it^^
-Brian aka Feilou