Question

Identify the molecule having empirical formula $C{H_2}O$
(A) $C{H_3}CHO$
(B) $HO - C{H_2} - C{H_2} - OH$
(C) ${C_2}{H_2}{O_4}$
(D) $C{H_3}COOH$

Answer 1

Hint : The empirical formula shows the simplest whole-number ratio in which the atoms can be expressed in a compound. This means that the $C{H_2}O$ can be written as the ${C_x}{H_{2x}}{O_x}$ where the value of x can be any whole number and we have to find out the value of x to answer this question. The value of x should also lead to proper organic compounds.

Complete Step By Step Answer:
To find the answer for the given question, we will have to adopt a method of trial and error. To do so we have to substitute the value of x in the below formula as any whole number.
$\Rightarrow {C_x}{H_{2x}}{O_x}$
When we put the value of x as 1 we will obtain the question itself and thus that is the empirical formula.
When we put the value of x as 2 we get
$\Rightarrow {C_2}{H_4}{O_2}$
Thus we can say that this molecular configuration can be rearranged as $C{H_3}COOH$ which is the molecular formula of acetic acid.
Here the total number of molecules remains the same. 2 Carbon atoms, 4 hydrogen atoms, and 2 oxygen atoms. This can be reduced to the empirical formula of $C{H_2}O$
Thus we can say that the correct option for this question is (D).

Note :
When dealing with the percentage of atoms in a given molecule it is always necessary to convert the molecular formula back to the empirical formula. This makes the calculations easier. In real life, the empirical formula is used to find out the molecular formula of the given sample. The empirical formula aids us in calculating the molecular formula which distinguishes compounds with the same elements and ratios from each other.