Final answer:
To find the percentage composition of menthol, masses of carbon and hydrogen are determined from CO₂ and H₂O produced in combustion. These masses are used to calculate the percentage of each element in menthol. The empirical formula is then determined from the mole ratio of the elements.
Step-by-step explanation:
The question concerns the combustion analysis of menthol and determination of its percent composition by mass and empirical formula. To calculate the percentages of carbon, hydrogen, and oxygen, we use the masses of CO₂ and H₂O produced in the combustion analysis. Every mole of CO₂ contains one mole of carbon, and for H₂O, every mole contains two moles of hydrogen.
To find the mass of carbon in CO₂, use the molar mass of carbon and CO₂ to determine how many moles of carbon are present in the given mass of CO₂ produced. Apply the same process to determine the mass of hydrogen in the H₂O produced. Already knowing the total mass of the menthol sample, and having the masses of carbon and hydrogen, you can subtract these from the total mass to find the mass of oxygen. After calculating the individual masses, divide each by the total mass of the sample and multiply by 100 to get the percentages.
For the empirical formula, you convert the masses of carbon, hydrogen, and oxygen to moles. Then, divide each by the smallest number of moles to get the simplest whole number ratio.