I have published a compilation of study notes on every topic of the CIE IGCSE Chemistry course (except topic 3 which I can't seem to find). Using these study notes, I got an A* in Chemistry (well actually a 9 out of 9) and I found that without them, this would have been impossible. Each document is...
Fuel: a substance that when burned, releases heat energy (that can be transferred into electricity)
14.1 NAMES OF COMPOUNDS
Hydrocarbons
→ A compound that contains only hydrogen and carbon atoms (e.g., alkanes, alkenes but NOT alcohols or carboxylic acids)
COMBUSTION OF HYDROCARBONS
→ These compounds undergo complete and incomplete combustion
1. Complete combustion
When does it occur? When there is an excess oxygen DIFFERENCES BETWEEN TYPES OF FORMULAS
What are the products? Water and carbon dioxide
: CH4+ 2O2→CO2+ 2H2O
2. Incomplete combustion
When does it occur? When there is insufficient oxygen to burn
What are the products? Either carbon monoxide and water OR carbon and water form
: 2CH4+ 3O2→ 2CO + 4H2O
: CH4+ O2→ C + 2H2O
How to name organic compounds
The prefix: tells you how many carbon atoms are present in the longest continuous chain in the compound
The suffix: tells you what functional group is on the compound
Esters are formed when... an alcohol reacts with a carboxylic acid
: therefore...
- the name of the ALCOHOL goes FIRST, getting rid of the -anol and adding -yl
- the name of the CARBOXYLIC ACID goes SECOND, getting rid of the -oic acid and adding -oate
Example:
Ethanoic acid + propanol → propyl ethanoate
Methanol + butanoic acid → methyl butanoate
-
(however, when drawing the structure of an ester, the carboxylic acid comes first)
14.2 FUELS
Fossil fuels → mainly organic compounds Fossil fuels all contain some sulfur compounds as impurities
→ most common fossil fuels:
1. coal
2. natural gas (its main constituent being methane: CH4 + some butane and other hydrocarbon gases)
3. petroleum (crude oil: found under porous rock under the ground & under the sea)(refining process before use, not other FF)
, LUCIA ROMERO
Refining of petroleum
• Petroleum itself as a mixture isn’t very useful but each component part of the mixture, called a fraction, is useful and each fraction has
different applications
How are the fractions of petroleum separated?
By fractional distillation in a fractionating tower
How?
The molecules in each fraction have similar properties and boiling points → depend on the number of carbon atoms in the chain
EXPLAINING THE PROCESS
➢ The fractionating column is hot at the bottom and cool at the top
1. Crude oil enters the fractionating column and is heated → vapors rise
2. Vapors of hydrocarbons with very high boiling points → immediately turn into liquid → tapped off at the bottom of the column
3. Vapors of hydrocarbons with low boiling points → rise up the column and condense at the top → tapped off
➢ The different fractions condense at different heights according to their boiling points and are tapped off as liquids.
- The fractions containing smaller hydrocarbons are collected at the top as gases (as they have the lowest boiling points and are the
most VOLATILE)
- The fractions containing bigger hydrocarbons are collected at the lower sections
PROPERTIES OF THE MAIN FRACTIONS OF CRUDE OIL
1. Viscosity: refers to the ease of flow of a liquid.
: high viscosity liquids are thick and flow less easily
: if the number of carbon atoms increases, the attraction between the hydrocarbon molecules also increases which results in the
liquid becoming more viscous → with the increasing length of the hydrocarbon chain (the liquid flows less easily with increasing
molecular mass)
2. Colour: as carbon chain length increases the colour of the liquid gets darker
THE FRACTIONS AND THEIR USES
Name of fraction Number of carbon atoms Use of that fraction
1. Refinery gas 1–4 i. bottled gas for:
- heating
- cooking
2. Gasoline 5-6 i. petrol for cars
3. Naphtha 6 - 10 i. raw material for:
- chemical production
- plastic production
4. Kerosene (paraffin) 10 - 15 i. fuel for:
- airplanes
- oil stoves
- oil lamps Boiling point & viscosity
5. Diesel (gas oil) 15 - 20 i. fuel for diesel engines increase going down
6. Fuel oil 20 - 30 i. fuel for:
- power stations
- ships
- home heating systems
7. Lubricating fraction 30 - 50 i. lubricants for
- car engines
- machinery
ii. waxes
iii. polishes
8. Bitumen 50 - upwards i. making roads
ii. covering roofs
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