Chemistry - Carboxylic acid and their Derivatives Question with Solution | TestHub

In acetylation, replacement of H of$\mathrm{O}-\mathrm{H}$occurs by$\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{O}-$group.$-\mathrm{O}-\boxed{\mathrm{H}+\mathrm{C}\mathrm{l}}\stackrel{\mathrm{O}}{\stackrel{\left|\right|}{\mathrm{C}}}-\mathrm{C}{\mathrm{H}}_3\to -\mathrm{O}\mathrm{C}\mathrm{O}\mathrm{C}{\mathrm{H}}_3+\mathrm{H}\mathrm{C}\mathrm{l}$

i.e., H atom of mass 1 amu is lost and an acetyl group of mass 43 amu is added. Thus, there is a net gain of 43 - 1 = 42 amu for every acetyl group introduced. Mass of difference of final product and original compound is 190 - 106 = 84.

Hence, number of$-\mathrm{O}\mathrm{H}$groups$=\frac{84}{42}=2$.