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Carbon and its Compounds — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceCarbon and its Compounds5 Marks
Question
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.
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Answer


Certain compounds contain only carbon and hydrogen. So, these organic compounds are called hydrocarbons.
General formula for the homologous series of alkanes = $C _n H _{2 n+2}$
$\ \ \ \ \ \ \text{H} \\ \ \ \ \ \ \ \ \text{|} \\ \text{H} {-} \text{C} {-} \text{H} \\ \ \ \ \ \ \ \ \text{|} \\ \ \ \ \ \ \ \text{H}$
General formula for the homologous series of alkenes = $C _n H _{2 n}$
First member of the alkene family is ethene.

General formula for the homologous series of alkynes = $C _n H _{2 n+2}$​​​​​​​
First member of the alkyne family is ethyne.
$\text{H} {-} \text{C} \equiv \text{C} {-} \text{H}$

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