Question

Predict and write the products for the below reaction.
$C{H_2} = C{H_2} + {H_2}\xrightarrow{{Ni}}C{H_3} - C{H_3}$ is an additional reaction.
$CH \equiv CH + {H_2}\xrightarrow{{Ni}}?$

Answer 1

Addition reaction in simplest words can be defined as where two or more molecules combine to form a larger one molecule.

Complete step by step answer:
Ethene reacts with hydrogen in the presence of a finely divided Nickel catalyst at about $150^oC$, then Ethane is produced.
$C{H_2} = C{H_2} + {H_2}\xrightarrow{{Ni}}C{H_3} - C{H_3}$

Additional:
This is a fairly pointless reaction because ethene is a much more useful compound than ethane.
When Ethyne reacts with hydrogen in the presence of a catalyst i.e. $Ni$ or $Pd$, Ethyne is converted into ethane.
The reaction stops here i.e. the obtained alkene does not react with hydrogen again because only one molecule of hydrogen is taken.
The reaction can be understood by the following reaction:
$CH \equiv CH + {H_2}\xrightarrow{{Ni}}C{H_2} = C{H_2}$

Additional Information: The double bond of an alkene consists of a sigma $\left( \sigma \right)$ bond and pi $\left( \pi \right)$ bond. Because the Carbon-Carbon $\left( {C - C} \right)\pi$ bond is relatively weak, it is quite reactive and can be easily broken and reagents can be added to carbon. Reagents are added through the formation of single bonds to carbon in an additional reaction.

Note: Hydrogenation reactions are extensively used to create commercial goods. This process is used in the food industry to make a large variety of manufactured goods like spreads and shortenings from the liquid oils.