Question

An organic substance 0.2115g on complete combustion gave 0.4655g of co2 and 0.2533g water. Determine the percentage of the compound

Answer 1

Soln.: Mass of CO2 formed = 0 .4655 g

Mass of Hp formed = 0.2533 g

Mass of the organic substance taken = 0.2115 g

Percentage of carbon =

Ex mass of CO2 xl00

44 mass of compound

Ex 0

.

4

655 xlO0 = 60.03

44 0.2 1 15

2 mass of H 0

Percentage of hydrngen = -X 2 X 1 00

18 mass of compound

= 2x 0

.

253� xl00 = 13.30

18 0.21 15

Percentage of oxygen = 1 00 - (60.03 + 13.30) = 26.67

Composition of the substance : C = 60.03%; H = 1 3.30%;

0 = 26.67%