Question

A solution of phenol in chloroform $\left({\mathrm{CHCl}}_3\right)$when treated with aqueous $\mathrm{NaOH}$ gives compound $\mathrm{P}$ as a major product. The mass percentage of carbon in $\mathrm{P}$ is: (to the nearest integer) (atomic mass : $\mathrm{C}=12,\mathrm{H}=1,\mathrm{O}=16$) -

Answer 1

1. When phenol in chloroform is treated with aqueous $\mathrm{NaOH}$, the Riemann Tiemann reaction takes place. It gives salicylaldehyde as a major product. the reaction is given below-
2. The major product P is salicylaldehyde. Its molecular formula is $\left({\mathrm{C}}_7{\mathrm{H}}_6{\mathrm{O}}_2\right)$. The molecular mass of salicylaldehyde is $122\mathrm{g}$
3. Calculation - mass % of carbon in a compound = $\frac{\mathrm{molar}\mathrm{mass}\mathrm{of}\mathrm{carbon}\mathrm{in}\mathrm{compoud}}{\mathrm{molecular}\mathrm{mass}\mathrm{of}\mathrm{compound}}\times 100$
4. Mass $\%$ of carbon in salicylaldehyde - $\frac{7\times 12}{122}\times 100=68.85\approx 69\%$

So, the mass $\%$ of carbon in P is $69\%$.