We’re being asked to determine the molecular formula of a Valproic Acid composed of C, H, and O given the combustion analysis, 0.165-g sample is combusted to produce 0.166 g of water and 0.403 g of carbon dioxide.
Recall that in combustion analysis, a compound reacts with excess O2 to form products.
For a compound composed of C, H, and O, the reaction looks like this:
CxHyOz + O2 (excess) → x CO2 + y H2O
This means we need to do the following steps:
Step 1: Calculate the mass of C and H in the compound.
Step 2: Calculate the mass of O in the compound.
Step 3: Determine the lowest whole number ratio of C, H, and O to get the empirical formula.
Step 4: Get the ratio of the molar mass and empirical mass to determine the molecular formula.