Question

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)

• A. 10.22 g
• B. 6.0 g
• C. 4.0 g
• D. 20.44 g

Hint:

In stoichiometric calculations, ensure that the moles of the reacting substance are correctly converted to mass using the molar mass. Pay attention to the number of atoms or molecules required for the reaction.

Answer 1

The Correct Option is A

We are given the following data: 
- Molar mass of phenol (C6H5OH) = 94 g/mol 
- Mass of phenol = 2 g 
- Molar mass of bromine = 80 g/mol 
We need to calculate how much bromine is required to convert the given mass of phenol into 2, 4, 6-tribromophenol. This requires the use of stoichiometry. First, calculate the moles of phenol:
\[ \text{moles of phenol} = \frac{\text{mass of phenol}}{\text{molar mass of phenol}} = \frac{2}{94} \approx 0.0213 \, \text{mol} \] Since 3 moles of bromine are required for 1 mole of phenol to form 2,4,6-tribromophenol, we need to calculate the moles of bromine required:
\[ \text{moles of bromine} = 3 \times 0.0213 = 0.0639 \, \text{mol} \] Now, calculate the mass of bromine required:
\[ \text{mass of bromine} = \text{moles of bromine} \times \text{molar mass of bromine} = 0.0639 \times 80 = 5.11 \, \text{g} \] Therefore, the required amount of bromine is 10.22 g.