Final answer:
The molecular formula of butylated hydroxytoluene (BHT) cannot be directly determined from the options provided as the calculated empirical formula from the combustion analysis data, C15H24O, does not match any of the given choices.
Step-by-step explanation:
To determine the molecular formula for butylated hydroxytoluene (BHT) from the given combustion data, one must first find the moles of carbon and hydrogen atoms in the sample by analyzing the combustion products, CO₂ and H₂O.
From the given data:
- 7.118 g of CO₂ corresponds to 7.118 g / 44.01 g/mol (molar mass of CO₂) = 0.1618 mol of CO₂. Since each CO₂ molecule contains one carbon atom, this also represents the moles of carbon in the original BHT sample.
- 2.331 g of H₂O corresponds to 2.331 g / 18.015 g/mol (molar mass of H₂O) = 0.1294 mol of H₂O. Since each H₂O molecule contains two hydrogen atoms, the moles of hydrogen in the sample is 2 x 0.1294 mol = 0.2588 mol.
Assuming that all the oxygen in the sample comes from BHT (no excess oxygen from air), we can calculate the moles of oxygen in BHT after subtracting the mass of carbon and hydrogen found as elements C and H from the original mass of BHT.
Mass of carbon: 0.1618 mol x 12.01 g/mol = 1.942 g
Mass of hydrogen: 0.2588 mol x 1.008 g/mol = 0.261 g
Mass of oxygen in BHT = 2.376 g (original BHT mass) - 1.942 g (C mass) - 0.261 g (H mass) = 0.173 g
Thus, moles of oxygen = 0.173 g / 16.00 g/mol = 0.01081 mol.
Finally, the molar ratio of C:H:O is approximately 0.1618:0.2588:0.01081, which simplifies to 15:24:1 when divided by the smallest number of moles (0.01081). This gives us the empirical formula of C₁₅H₂₄O, which does not match the choices given. Thus, there seems to be a mistake in the calculation, or in the provided options.