Question

A 2.00 gram sample of a compound gave 4.86 grams of carbon dioxide and 2.03 grams of water upon combustion in oxygen. find its empirical formula, if it only contained Carbon, Hydrogen and Oxygen

Answer 1

Answer:

Mass of C in 4.86 g CO2 = 4.86 g *12 / 44 = 1.325 g C

Mass H in 2.03 g H2O = 2.03 g * 2/18 = 0.225 g H

Mass of O = 2.00 g - ( 1.325 + 0.225 ) = 0.45 g O

Divide each mass by respective molar mass

C = 1.325 / 12 = 0.1104

H = 0.225 / 1 = 0.225

O = 0.450/16 = 0.028

Divide through by smallest

C = 0.1104 /0.028 = 3.925 ( round to 4 )

H = 0.225 / 0.028 = 8.03

O = 0.028/0.028 = 1 .00

Empirical formula = C4H8O