Question

4.7 g of phenol is heated with Zn to give product X. If this reaction goes to 60% completion then the number of moles of compound X formed will be ________ $\times 10^{-2}$. (Nearest Integer)
(Given molar mass in $\text{g mol}^{-1}$ : H:1, C:12, O:16)

Hint:

Reduction of phenol with Zn dust gives benzene. Calculate moles of phenol first, then apply the 60% yield factor.

Answer 1

Correct Answer: 3

When phenol is reduced with Zinc dust, benzene is produced. We need to find the number of moles of benzene produced from 4.7g of phenol at 60% yield.

1. Reaction: $\text{Phenol} + \text{Zn} \rightarrow \text{Benzene} + \text{ZnO}$
2. Molar mass of Phenol ($C_6H_6O$): $(12 \times 6) + (1 \times 6) + 16 = 94\text{ g/mol}$
3. Initial moles of Phenol: $4.7 / 94 = 0.05\text{ mol}$
4. Based on the chemical equation, the theoretical yield of benzene is 1 mole for every 1 mole of phenol. So, the theoretical yield is $0.05\text{ moles}$.
5. The reaction is only $60\%$ complete, so actual moles of benzene (X) $= 0.05 \times 0.6 = 0.03\text{ moles}$.
6. Representing $0.03$ in scientific notation as per the question: $3 \times 10^{-2}$.

Therefore, the integer to be filled in the blank is 3.