Answer:
C₆H₆
Explanation:
We need to find the molecular formula of a compound of carbon (C) and hydrogen (H), so what we need to find out is the number of atoms of C and of H in the molecule. We know:
So, in 1 mol of compound, 92.3% of the mass corresponds to Carbon:
mass of C / mol of compound = molar mass × C% = 78.1 g/mol × 92.3/100 = 72.1 g/mol
moles of C = mass C / molar mass C = 72.1 g / 12.011 g/mol
moles of C = 6 moles of C per mol of compound
If 72.1 g in a mol of compound are Carbon atoms, the difference between the molar mass and the mass of Carbon atoms will correspond to H atoms in 1 mol of compound:
mass of H / mol of compound = molar mass - mass of C/mol
mass of H = 78.1 g / mol - 72.1 g /mol = 6.0 g/mol of compound
moles of H = mass H / molar mass H = 6.0 g / 1.008 g/mol
moles of H = 6.0 moles of H per mol of compound
So one mol of compound has 6 moles of C and 6 moles of H.
The molecular formula is then written as C₆H₆
