Final answer:
The percent by mass of hydrogen in a benzene ring, C6H6, is approximately 7.76%.
Step-by-step explanation:
To calculate the percent by mass of hydrogen in a benzene ring, which has the molecular formula C6H6, we need to consider the molar masses of carbon and hydrogen. Carbon has a molar mass of approximately 12.01 g/mol, and hydrogen has a molar mass of about 1.01 g/mol. Since benzene has six carbon atoms and six hydrogen atoms, the total molar mass of benzene is (6 × 12.01) + (6 × 1.01) = 78.06 g/mol. The mass contributed by hydrogen in benzene is (6 × 1.01) = 6.06 g/mol.
To find the percent by mass of hydrogen, we use the formula: Percent by mass of H = (mass of hydrogen in the compound / molar mass of the compound) × 100%. Substituting the values, we get: Percent by mass of H = (6.06 g/mol / 78.06 g/mol) × 100% ≈ 7.76%.
Therefore, the percent by mass of hydrogen in a benzene ring is approximately 7.76%.