Question

Cyclohexanol is dehydrated to cyclohexene on heating with conc. \(H_2SO_4\). If the yield of this reaction is 75% how much cyclohexene will be obtained from 100 g of cyclohexanol?

• A. 61.5 g
• B. 75.0 g
• C. 20.0 g
• D. 41.0 g

Hint:

Always multiply theoretical yield by percentage yield.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This problem involves calculating the actual yield of a product based on the theoretical yield (stoichiometry) and the percentage yield given.
: Key Formula or Approach:
1. Moles \( = \frac{\text{Mass}}{\text{Molar Mass}} \)
2. Theoretical Yield \( = \text{Moles of reactant} \times \text{Molar Mass of product} \)
3. Actual Yield \( = \text{Theoretical Yield} \times \frac{\text{Percentage Yield}}{100} \)
Step 2: Detailed Explanation:
Reaction: \( \text{C}_{6}\text{H}_{11}\text{OH (Cyclohexanol)} \xrightarrow{\text{conc. H}_{2}\text{SO}_{4}} \text{C}_{6}\text{H}_{10} \text{ (Cyclohexene)} + \text{H}_{2}\text{O} \)
1. Molar Masses:
- Cyclohexanol (\( \text{C}_{6}\text{H}_{12}\text{O} \)): \( (6 \times 12) + (12 \times 1) + 16 = 100 \text{ g/mol} \)
- Cyclohexene (\( \text{C}_{6}\text{H}_{10} \)): \( (6 \times 12) + (10 \times 1) = 82 \text{ g/mol} \)
2. Calculate Moles of Reactant:
- Moles of Cyclohexanol \( = \frac{100 \text{ g}}{100 \text{ g/mol}} = 1.0 \text{ mole} \)
3. Calculate Theoretical Yield of Product:
- Since 1 mole of reactant gives 1 mole of product, theoretical moles of cyclohexene \( = 1.0 \text{ mole} \).
- Theoretical Mass \( = 1.0 \text{ mol} \times 82 \text{ g/mol} = 82 \text{ g} \).
4. Calculate Actual Yield:
- \( \text{Actual Yield} = 82 \text{ g} \times \frac{75}{100} = 82 \times 0.75 = 61.5 \text{ g} \).
Step 3: Final Answer:
The amount of cyclohexene obtained is 61.5 g.