Question

A laboratory analysis produced the following mass percent data: 48.5 C, 3.9 H, and 47.5 O.
Find the empirical formula of the compound.

Answer 1

Hint: Solve the question by hit and trial method. Evaluate each option with the data given in the question and try to find the option closest to the values. Find the total mass of the organic compound. Find the mass percentage of C, H and O in the empirical formula for the compound. This will work because the ratio will remain the same in case of the empirical formula as well.

Complete step by step answer:
In chemistry, the empirical formula of a chemical compound indicates the simple positive integer ratio of atoms present in a compound.
Let us consider any one of the above-mentioned compounds. The compound under consideration is ${{C}_{4}}{{H}_{4}}{{O}_{3}}$. We will now calculate the mass of this compound.
Mass of carbon atom = 12 g
Mass of hydrogen atom = 1 g
Mass of oxygen atom = 16 g
Total mass of compound becomes,
(4 x 12.0107) + (4 x 1.00794) + (3 x 15.9994) = 100.0728
We will now calculate mass percentage for each atom of the compound.
Mass percentage for carbon = 48.5
Mass percentage for hydrogen = 3.9
Mass percentage for oxygen = 47.5
So, the correct answer is “Option B”.

Note: It is important to know that empirical formula gives a simple ratio of atoms present in the compound. You cannot determine a molecular formula with the empirical formula alone. Structure formula cannot be determined as well by this method.