Chemistry

Hydrocarbons (continued)


Alcanos

Alcanos they are hydrocarbons formed only by simple bonds between their carbons. They have open chain (acyclic) and simple (saturated) bonds. Its formula is:

ÇnoH2n + 2

The main source of alkanes is petroleum and natural gas. From them it is possible to produce fuels such as gasoline, diesel oil and kerosene. These alkanes are low carbon. For longer chains it is possible to obtain paraffin (candle making).

Physical properties

Alkanes are poorly reactive, ie react with almost no substance. For this reason, they are also called paraffins or paraffinic. In latinfor affinis means little affinity.

They are not very reactive because the bonds between C - H and C - C are very stable and difficult to break. They are mostly used for burning, so they are used as fuels for the supply of energy.

They are insoluble in water and less dense than water. Alkanes of up to four carbons are gases at room temperature (25 ° C). From five to seventeen carbons are liquids and the rest are solids. Note the number of carbons, the physical state and the substance:

Compound

Carbon N °

Physical state (25 ° C)

Product

Methane

1

gaseous

Natural gas

Propane

3

gaseous

LPG

Butane

4

gaseous

LPG

Octane

8

liquid

Gasoline

Dean

10

liquid

Kerosene

Tricosano

30

solid

Tar (asphalt)

* LPG = liquefied petroleum gas

Nomenclature

To name alkanes, as with other organic compounds, we must follow the rules established by the International Union of Pure and Applied Chemistry (IUPAC).

Prefix + Center Part + Termination

Prefix: Indicates the number of carbons in the chain. They are of Greek or Latin origin.

1C - met
2C - et
3C - prop
4C - but
5C - pent
6C - hex
7C - hept
8C - oct
9C - non
10C - dec
11C - undec
12C - dodec
20C - eicos
30C - Tricos

These prefixes also serve other organic functions.

The center, the middle part, the nucleus: Indicates the type of chemical bond between carbons. For alkanes, we use an.

an = simple call
en = double bond
in = triple bond

Termination or suffix: indicates the chemical function. Since the function is hydrocarbon, we use the letter O.

Examples:
CH4 - methane
Ç2H6 - ethane

Ç8H18 = octane

Ç5H12 = pentane