Single Choice

In which case the reaction is most exothermic with $$H_2$$ Ni.

A
B
Correct Answer
C
D

Solution

Heat of reaction is nothing but the difference in the energy of initial and final molecules. Hydorgenation of all 4 of them give ethyl-cylcohexane. Hence the amount of heat released depends on the energy of initial molecule. Lesser the stability if the molecule higher its energy.
And the greater the number of attached alkyl groups (i.e., the more highly substitutedthe carbon atoms of the double bond), the greater is the alkenes stability. Refer the figure.
Hence in the given options, the stability order is
A and D (tri-substituted)>C(disubstituted)>B(mono substituted)
B- is the least stable one$$\Rightarrow$$ has highest energy$$\Rightarrow$$most exothermic

SIMILAR QUESTIONS

Hydrocarbons

Ethylene is converted to ethane in the presence of $$Ni$$ at $$300^{0}C$$ . In this reaction the hybridization of carbon changes from :

Hydrocarbons

A hydrocarbon $$'X'$$ adds on one mole of hydrogen to give another hydrocarbon and decolourised bromine water. $$'X'$$ reacts with $${ KMnO }_{ 4 }$$ in the presence of acid to give two moles of the same carboxylic acid. The structure of $$'X'$$ is:

Hydrocarbons

Hydrogenation of $$C_{6}H_{5}CHOHCOOH$$ over $$Rh -Al_{2}O_{3}$$ gives :

Hydrocarbons

Compound(s) that on hydrogenation produce(s) optically inactive compound(s) is(are):

Hydrocarbons

Which one of the following alkenes will react faster with $$H_2$$ under catalytic hydrogenation conditions?

Hydrocarbons

Write structures of all the alkenes which on hydrogenation give 2 - methylbutane.

Hydrocarbons

Give the formula and name of $$A, B, C$$ and $$D$$ in the following equations: $$C_2H_2 \xrightarrow {H_2}\ A \xrightarrow{H_2}\ B\ \underset{-HBr}{\xrightarrow {Br_2}}\ C\ \underset{-HBr}{\xrightarrow {Br_2}}\ D$$

Hydrocarbons

Addition reaction and substitution reaction are type of organic reactions. Which type of reaction is shown by ethene?

Hydrocarbons

Which one of the following alkenes will react faster with $$H_2$$ under catalytic hydrogenation conditions?

Hydrocarbons

The gas used in the hydrogenation of oils in presence of nickel as a catalyst is:

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