1. Hydrocarbon
MUST Remember!
Hydrocarbons are organic compounds that contain only carbon and
hydrogen.
1. Hydrocarbon is a compound made out of the elements carbon and
hydrogen only.
2. Examples of hydrocarbon are alkane, alkene and alkyne.
3. Hydrocarbon can be divided into two groups:
a. saturated hydrocarbon
Saturated hydrocarbons are hydrocarbons where all its carbon
atoms are tied to each other through single covalent bond only.
Examples: alkanes
Saturated Hydrocarbon
b. unsaturated hydrocarbon
Unsaturated hydrocarbons are hydrocarbons which contains at
least one double covalent bond among its carbon atoms.
Examples: alkenes
Unsaturated Hydrocarbon

2. 4. Ethanol ( C2H5OH ), ethanoic acid (CH3COOH), metal methanoat
(HCOOCH3), chloromethane (CH3Cl) and others are not hydrocarbons
because the molecule contains other elements such as chlorine or
oxygen other than carbon and hydrogen.
MUST Know!


Saturated - All single bond between carbons
Unsaturate - Has at least one double/triple bond between carbons
Comparing Saturated and Unsaturated Hydrocarbon
Saturated
Hydrocarbon
Combustion
Unsaturated
Hydrocarbon
Produce less soot
Produce more
soot
Reaction with bromine The brown colour
water
of bromine
remain
unchanged
Decoloarise the
brown colour of
bromine
Reaction with
potassium
manganate(VII)
solution
Decolourise the
purple colour of
potassium
manganate (VII)
solution
Sources of Hydrocarbon:
The purple colour
of potassium
manganate (VII)
solution remain
unchanged

3. The main sources of hydrocarbons are
a.
b.
c.
Coal
Natural gas
Petroleum
Combustion of Hydrocarbon
All hydrocarbons undergo combustion with oxygen to produce carbon dioxide
(or carbon monoxide/carbon) and water. There are 2 types of combustion:
a. Complete combustion – organic compounds burn completely which
form CO2 and H2O
b. Incomplete combustion– organic compounds burn with limited supply
of O2which form C (soot), CO, CO2 and H2O.
Example
Complete combustion
C2H6 + 7/2 O2 → 2CO2 + 3H2O
C3H6 + 9/2 O2 → 3CO2 + 3H2O
Incomplete combustion
C2H6 + 5/2 O2 → 2CO + 3H2O
C2H6 + 3/2 O2 → 2C + 3H2O
C3H6 + 3O2 → 3CO + 3H2O
C3H6 + 3/2 O2 → 3C + 3H2O
Note:
1. The soot from the combustion of a hydrocarbon depends on the
percentage of carbon it contains.
2. Higher carbon percentage in the hydrocarbon molecule will result
sootier flame.