An unknown pesticide is made up of 18.28 percent carbon 0.77 percent hydrogen and 80.95 percent chlorine What is the empirical formula of the pesticide?

Answer 1

I assume that these are weight percents. If so, assume you have 100 g of the substance. Then divide each by the molecular weight to find the number of moles of C, H, & Cl.

C: 18.28 g * (1 mole C/12.011 g C) = 1.522 moles C

H: 0.77 g * (1 mole H/1.008 g H) = 0.764 moles H

Cl: 80.95 g * (1 mole Cl/35.453 g Cl) = 2.283 moles Cl

Next find the ratio of moles of C to H to Cl. To do this divide each by the smallest number of moles from the list, in this case it will be hydrogen.

C: 1.522/0.764 = 1.99 (round it to 2)

H: 0.764/0.764 = 1.00

Cl: 2.283/0.764 = 2.99 (round it to 3)

So your empirical formula of the pesticide should be C2HCl3