: Use the given density (relative to air or hydrogen) to find the true molecular formula.

If you are stuck on a "combustion" problem from the book, use this standard logic: : Convert masses of CO2cap C cap O sub 2 H2Ocap H sub 2 cap O to moles of Check for Oxygen : Subtract the mass of from the total substance mass. Determine Ratio : Find the simplest whole-number ratio of

: Finding formulas based on mass fractions of elements (C, H, O) or combustion products ( CO2cap C cap O sub 2 H2Ocap H sub 2 cap O