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
19 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 1

Answer:

1. Certain compounds are called hydrocarbons because they are a group of compounds which are made up of hydrogen and carbon. The homologous group of compounds are like alkanes, alkenes, alkynes, etc. The alkanes only have carbon atoms that are attached to the other carbon atoms through single bonds.
2. The general formula of homologous series alkanes is CnH2n+2. The general formula of homologous series alkenes is CnH2n. The general formula of homologous series alkynes is CnH2n−2. The first member of alkanes homologous series is methane.
3. Answer. The name of the reaction that converts alkenes to alkanes is addition reaction. The addition reaction is normally characteristic of alkenes because of the presence of the double bond. This reaction normally takes place when alkene is heated with hydrogen gas in the presence of nickel catalyst

Answer 2

→ Some compounds are called hydrocarbon because they contain hydrogen and carbon only . For example: C₂H₆ ,CH₄

⭐General Formula⭐

→ Alkanes: CₙH₂ₙ${_{+}}₂$

→ Alkenes:CₙH₂ₙ

→ Alkynes:CₙH₂ₙ${_{−}}₂$

•The structure of the first member of each series is provided in the image given above. The first member of Alkane is Methane and first members of Alkene and Alkyne are Ethene and Ethyne since their Methene and Methyne are not possible. Infact there's nothing named as methene and mythyne in chemistry.

▪The reaction that converts alkenes to alkanes is called an addition reaction.

CH₂=CH₂ + H₂ +(Heat)====> CH₃−CH₃

For such reactions to take place catalysts like Raney Ni, Pt and Pd are used.