Question

9.3 g of pure aniline upon diazotisation followed by coupling with phenol gives an orange dye. The mass of orange dye produced (assume 100% yield/ conversion) is ________g. (nearest integer)

Answer 1

Correct Answer: 20

The reaction proceeds as follows:
\[\text{C}_6\text{H}_5\text{NH}_2 + \text{NaNO}_2 + \text{HCl} \xrightarrow{T<5^\circ \text{C}} \text{C}_6\text{H}_5\text{-N}_2^+\text{Cl}^-\xrightarrow{\text{Phenol}} \text{Orange Dye}\]
One mole of aniline (C$_6$H$_5$NH$_2$) yields one mole of orange dye.
Aniline's molar mass is 93 g mol$^{-1}$.
Orange dye's molar mass is 199 g mol$^{-1}$.
The calculation for moles of aniline used is:
\[\text{moles of aniline} = \frac{\text{mass of aniline}}{\text{molar mass of aniline}} = \frac{9.3}{93} = 0.1 \, \text{mol}.\]

The mass of orange dye produced is calculated as:
\[\text{mass of orange dye} = \text{moles of aniline} \times \text{molar mass of orange dye} = 0.1 \times 199 = 19.9 \, \text{g} \approx 20 \,\text{g}.\]