Question

An organic compound A on heating with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ forms a compound B which on addition of one mole of hydrogen in presence of $\mathrm{Ni}$ forms a compound C. One mole of compound C on combustion forms two moles of ${\mathrm{CO}}_2$ and $3$ moles of ${\mathrm{H}}_2\mathrm{O}$. Identify the compounds A, B and C and write the chemical equations of the reactions involved.

Answer 1

Step 1: An organic compound A on heating with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ forms a compound B:

• Compound A is Ethanol forms compound B which is Ethene.
• The chemical reaction can be depicted as:

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\underset{{\mathrm{H}}_2{\mathrm{SO}}_4}{\overset{\mathrm{Conc}.}{\to }}{\mathrm{H}}_2\mathrm{C}={\mathrm{CH}}_2$

Step 2: On addition of one mole of hydrogen in presence of $\mathrm{Ni}$ forms a compound C.

• Then in addition of one mole of ${\mathrm{H}}_2$with the presence of $\mathrm{Ni}$ forms compound C.
• The chemical reaction can be depicted as:

${\mathrm{CH}}_2={\mathrm{CH}}_2+{\mathrm{H}}_2\stackrel{\mathrm{Ni}}{\to }{\mathrm{CH}}_3-{\mathrm{CH}}_3$

Step 3: One mole of compound C on combustion forms two moles of ${\mathrm{CO}}_2$ and $3$ moles of ${\mathrm{H}}_2\mathrm{O}$.

• One mole of compound C which is Ethane on combustion forms two moles of ${\mathrm{CO}}_2$ and $3$ moles of ${\mathrm{H}}_2\mathrm{O}$.
• The chemical reaction can be depicted as:

${\mathrm{CH}}_3-{\mathrm{CH}}_3+$$\frac{7}{2}$${\mathrm{O}}_2\to 2{\mathrm{CO}}_2+3{\mathrm{H}}_2\mathrm{O}$.

Therefore, Compound A is Ethanol $\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\right)$ , B is Ethene $\left({\mathrm{CH}}_2={\mathrm{CH}}_2\right)$, C is Ethane $\left({\mathrm{C}}_2{\mathrm{H}}_6\right)$.