A sample of an unknown compound has a percent composition of 52.14% carbon, 13.13% hydrogen, and 34.73% oxygen. Which compounds could the sample be?

The two possible compounds are;

1) Dimethyl Ether H₃C--O--CH₃

2) Ethanol H₃C--CH₂--OH

Solution:

Step 1: Calculate Moles of each Element;

Moles of C = %C : At. Mass of C

Moles of C = 52.14 : 12.01

Moles of C = 4.341 mol

Moles of H = %H : At. Mass of H

Moles of H = 13.13 : 1.01

Moles of H = 13.00 mol

Moles of O = %O : At. Mass of O

Moles of O = 34.73 : 16.0

Moles of O = 2.170 mol

Step 2: Find out mole ratio and simplify it;

C H O

4.341 13.00 2.170

4.341/2.170 13.00/2.170 2.170/2.170

2 5.99 1

2 6 1

Hence, Empirical Formula = C₂H₆O

Result:

As the molecular mass of compound is not given therefore, we can assume and guess the empirical formula to be the molecular formula. Hence, possible compounds are,

1) Dimethyl Ether H₃C--O--CH₃

2) Ethanol H₃C--CH₂--OH