Question

Fill in the Blanks A 27.0 g sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 g of carbon dioxide and 27 g of water. How many carbon and hydrogen atoms make up the empirical formula of this hydrocarbon? C atoms: Hatoms:

Answer 1

Moles of Carbon dioxide ( CO₂ ) = weight in gm / molar mass = 88 gm / 44 gm mol^—1 = 2 mol

moles of H₂O = 27 gm / 18 gm mol^—1 = 1.5 mol

moles of carbon = moles of CO₂ = 2mol

moles of Hydrogen = 2 x moles of H₂O = 2 x 1.5 = 3 mol

C atoms = 2

H atoms = 3