Question

In the following reaction.

The percentage mass of hydrogen in the product (R) is.

Answer 1

12.5%

Answer 2

The given reaction is a Wittig reaction between cyclohexanone and methylenetriphenylphosphorane ($Ph_3P=CH_2$), converting the ketone into an alkene. The product (R) is methylenecyclohexane ($C_7H_{12}$).

To calculate the percentage mass of hydrogen in $C_7H_{12}$:

1. Calculate the molar mass of $C_7H_{12}$:

   • Molar mass of C = 12 g/mol
   • Molar mass of H = 1 g/mol
   • Molar mass of $C_7H_{12} = (7 \times 12) + (12 \times 1) = 84 + 12 = 96$ g/mol

2. Calculate the mass of hydrogen in one mole of $C_7H_{12}$:

   • Mass of hydrogen = $12 \times 1 = 12$ g

3. Calculate the percentage mass of hydrogen:

   • Percentage mass of hydrogen $= \frac{\text{Mass of hydrogen}}{\text{Molar mass of } C_7H_{12}} \times 100\%$
   • Percentage mass of hydrogen $= \frac{12}{96} \times 100\% = \frac{1}{8} \times 100\% = 12.5\%$

Therefore, the percentage mass of hydrogen in the product (R) is 12.5%.