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molecular formula and empirical formula for quinine?

hello everyone, please help me to find the solution for this problem. Quinine is a constituent of tonic water and medicine for malaria. In the combustion of 0.487 g of quinine 1.321g of CO2, 0.325g of H2O and 0.421g of N2 are formed. The molar mass was determined to be 324 g\mol. Find the empirical and molecular formula of quinine. thanking you abhijit

Public Comments

1. Where are you stuck on this? First of all, the resdues and original mass let you find the amount of O2 consumed by simple arithmetic. That completes the chemical equation. Now, you should be able to use atomic weights to figure out how much of each element is in the residue. Work backwards to figure out how much of each was in the original quinine. Divide each amount by the element's atomic weight, and that will give you the relative proportions in atoms, from which you get the empirical formula. Figure the atomic weight of that, compar with the molar mass, and adjust by the proper factor to get the given figure of 324 g/mol. Does that do it?