Mass of original sample – (mass of C + mass of H) = mass of OĢ) Convert those masses to moles using the molar masses of each element (on periodic table). This is the mass of H in your 3.50 g sample.Į) Determine the mass of O in your unknown sample by difference: That is the mass of C in your 3.50 g sample.Ĭ) figure out the mass percent of H in H 2 O as you did in part a).ĭ) multiply the mass of the H2O from the analysis by the mass percent of H in H 2 O (as you did in part b). The subscripts in an empirical formula would represent moles of atoms in a mole of the unknown compound, so you will figure out:ġ) The masses of C, H, O present in the sample with the following steps:Ī) figure out the mass percent of C in CO 2 : mass of 1 mol C / mass of 1 mol CO2 x 100ī) multiply the mass of the CO 2 from the analysis by the mass percent (decimal form, 0.65, rather thanĦ5%) of C in CO 2.
The mass of CO 2 will lead you to the amount of C present in the sample, the mass of H 2 O will lead you to the amount of H present in the sample, and you can calculate the amount of O by difference. What is the empirical formula of the unknown compound? Insert subscripts as needed. Combustion of 3.50 g of this compound produced 8.24 g CO 2 and 2.25 g H 2 O . An unknown compound contains only C , H , and O .