Question

Write the name and general formula of the chain of hydrocarbons in which additional reactions with hydrogen can take place. Stating the essential conditions required for the additional reaction to occur, write the chemical equation giving the name of the reactant and the product of such a reaction.

Answer 1

Hydrocarbons are the compounds containing the hydrogen and carbon essentially. They are of two types: saturated and unsaturated hydrocarbons. Alkanes are saturated compounds and the alkenes and alkynes are unsaturated compounds.

Complete step by step answer:
The chains of hydrocarbons in which additional reactions with hydrogen can take place are the unsaturated hydrocarbons alkenes and alkynes because of the presence of the double and the triple bonds in them. They have the general formula of ${C_n}{H_{2n}}$and ${C_n}{H_{2n - 2}}$ due to the presence of the double and the triple bond the addition of the hydrogen can take place easily in them.
The essential conditions required for the addition reaction to occur, is the presence of the unsaturation in the bond which includes the double and the triple bond in the compound. Thus the unsaturated hydrocarbons alkenes and the alkynes will undergo the addition reactions.
Addition reactions of Alkenes:
The addition of the hydrogen to a molecule of ethene will result in the formation of the alkane molecule ethane. The reaction can be given as:
$C{H_2} = C{H_2} + {H_2}\xrightarrow{{Ni}}C{H_3} - C{H_3}$
Here Ni acts as the catalyst in the reaction. It accelerates the rate of the reaction without undergoing any change in them.
Addition reactions of Alkynes:
The addition of the hydrogen to a molecule of ethyne will result in the formation of the alkane molecule ethane. The reaction can be given as:
$CH \equiv CH + 2{H_2}\xrightarrow{{Ni}}C{H_3} - C{H_3}$.
Here Ni acts as the catalyst in the reaction. It accelerates the rate of the reaction without undergoing any change in them.

Note:
Alkanes are the saturated hydrocarbons made of hydrogen and carbon of the molecular formula ${C_n}{H_{2n + 2}}$, they do not undergo addition reactions instead they undergo elimination and substitution reactions. Thus the type of the reactions varies with the nature of the hydrocarbon.