question_answer

Why are certain compounds called hydrocarbons? Write the general formula for homologous series of alkanes, alkenes and alkynes and also draw the structure of the first member of each series. Write the name of the reaction that converts alkenes into alkanes and also write a chemical equation to show the necessary conditions for the reaction to occur.

Answer:

Compounds consisting of carbon and hydrogen are known as hydrocarbons.

(a) Saturated hydrocarbons: Alkanes \[({{C}_{n}}{{H}_{2n+2}})\] are the compounds of carbon which have single bond.

\[H-\underset{\begin{smallmatrix}  | \\  H \end{smallmatrix}}{\overset{\begin{smallmatrix}  H \\  | \end{smallmatrix}}{\mathop{C}}}\,-H\]

(b) Unsaturated hydrocarbons: The compounds of carbon having double bonds are alkene \[({{C}_{n}}{{H}_{2n}})\] and having triple bonds are alkyne\[({{C}_{n}}{{H}_{2n-2}})\].

The reaction which converts unsaturated hydrocarbons to saturated hydrocarbons i.e. alkenes to alkane is known as hydrogenation reaction. It is used to obtain ghee from oil.