JEE Main 2025 Jan 23 Shift 1, Chemistry Q15: Properties of Phenol

JEE Main2025Jan 23, Shift 1Chemistry

What amount of bromine will be required to convert 2 g of phenol into 2, 4, 6-tribromophenol ?

(Given molar mass in g mol $^{- 1}$ of C, H, O, Br are 12, 1, 16, 80 respectively)

Solution

The stoichiometry is $C_{6} H_{5} O H + 3 B r_{2} \to C_{6} H_{2} B r_{3} O H + 3 H B r$ , so 1 mole of phenol needs 3 moles of $B r_{2}$ .

Moles of phenol $= \frac{2}{94} \approx 0.0213$ mol.

Moles of $B r_{2}$ needed $= 3 \times 0.0213 \approx 0.0638$ mol.

Mass of $B r_{2} = 0.0638 \times 160 \approx 10.22$ g.

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