Question

The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. combustion of 3.61 mg of ethyl butyrate produces 8.22 mg of co2 and 3.35 mg of h2o. what is the empirical formula of the compound

Answer 1

Empirical Formula = C₃H₆O₁

Solution:

Data Given:

Mass of Ethyl Butyrate = 3.61 mg = 0.00361 g

Mass of CO₂ = 8.22 mg = 0.00822 g

Mass of H₂O = 3.35 mg = 0.00335 g

Step 1: Calculate %age of Elements as;

%C = (mass of CO₂ ÷ Mass of sample) × (12 ÷ 44) × 100

%C = (0.00822 ÷ 0.00361) × (12 ÷ 44) × 100

%C = (2.277) × (12 ÷ 44) × 100

%C = 2.277 × 0.2727 × 100

%C = 62.09 %

%H = (mass of H₂O ÷ Mass of sample) × (2.02 ÷ 18.02) × 100

%H = (0.00335 ÷ 0.00361) × (2.02 ÷ 18.02) × 100

%H = (0.9279) × (2.02 ÷ 18.02) × 100

%H = 0.9279 × 0.1120 × 100

%H = 10.39 %

%O = 100% - (%C + %H)

%O = 100% - (62.09% + 10.39%)

%O = 100% - 72.48%

%O = 27.52 %

Step 2: Calculate Moles of each Element;

Moles of C = %C ÷ At.Mass of C

Moles of C = 62.09 ÷ 12.01

Moles of C = 5.169 mol

Moles of H = %H ÷ At.Mass of H

Moles of H = 10.39 ÷ 1.01

Moles of H = 10.287 mol

Moles of O = %O ÷ At.Mass of O

Moles of O = 27.52 ÷ 16.0

Moles of O = 1.720 mol

Step 3: Find out mole ratio and simplify it;

C H O

5.169 10.287 1.720

5.169/1.720 10.287/1.720 1.720/1.720

3.00 5.98 1

3 ≈ 6 1

Result:

Empirical Formula = C₃H₆O₁