Question

Mention whether the given statement is right or wrong. If wrong, write the correct sentence.
Propane is an unsaturated hydrocarbon.

Answer 1

Hint: The degree of unsaturation of any hydrocarbon is determined by the presence of a multiple bond or a closed ring system. A saturated alkane neither has a multiple bond system nor a closed ring system. In the case of a ring system, the word ‘cyclo’ is added in the name of the alkane.

Complete step by step answer:
Propane is a saturated system and the degree of unsaturation in propane is zero. The degree of unsaturation of any system is determined by the formula:
$DOU = \dfrac{{2C + 2 + N - H - X}}{2}$
Where, C = Number of carbon atoms present in the compound
N = Number of nitrogen atoms present in the compound
H = Number of hydrogen atoms present in the compound
X = Number of halogen atoms present in the compound
Now, in the case of propane, whose structure is:
$C{H_3} - C{H_2} - C{H_3}$
The number of carbon atoms in propane = 3
The number of hydrogen atoms in propane = 8
As there are no nitrogen or halogen groups in propane, thus on applying the formula of the degree of unsaturation, we have:
$DOU = \dfrac{{2 \times 3 + 2 - 0 - 8 - 0}}{2} = 0$

Hence, we can clearly state that propane is a saturated hydrocarbon.

Note:
For finding the degree of unsaturation, one must check for the presence of a multiple bond system or a closed ring system. If not present, then the compound is said to be saturated.Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible.