A compound containing only CHO was extracted from the bark of the Sassafras tree

Question

A compound containing only C,H,O was extracted from the bark of the Sassafras tree. The combustion of 29.9 grams produced 81.3 grams of CO2 and 16.6 grams of H2O. The molar mass of the compound was 162/mole. Determine its empirical and molecular formula

Answer 1

The answer is something like this:

mass of C in the compound = (81.3g CO₂)x (12.0 g C/44.0 g CO₂) = 22.17 g C

mass of H in compound = (16.6 g H₂O) x (2.0 g H /18.0 g H₂O) = 1.84 g H

mass of O in compound = 29.9 g total - 22.17 g C - 1.84 g H = 5.89 g O

now convert mass of each element to moles

22.17 g C x (1 mole C/12.0 g C) = 1.85 moles C

1,84 g H x (1 mole H/1.0 g H) = 1.84 moles H

5.89 g O x (1 mole O/a6.0 g O) = 0.368 moles O

divide each by 0.389 to get C₅H₅O, which has a mass of 81 g

double that to get C₁₀H₁₀O₂

This is a "classic" example of a combustion analysis problem. Hope that helped.