Question

What is an empirical formula? Give an example for a compound whose empirical formula and molecular formula are the same.

Answer 1

Hint: A formula that gives the simplest whole number ratio of atoms in a compound is known as empirical formula. We can calculate the empirical formula with the help of molecular formula as:
$
  molecular{\text{ }}formula = n \times empirical{\text{ }}formula \\
   \Rightarrow empirical{\text{ }}formula = \dfrac{{molecular{\text{ }}formula}}{n} \\
$
Where n is the simple whole number have the value 1, 2, 3…, n.

Complete step by step answer: Empirical formula is defined as the formula of a compound which gives the simple whole number ratio of the atoms of various elements present in one molecule of compound.
Let us consider an example, the molecule of hydrogen peroxide has the molecular formula ${H_2}{O_2}$. The simple whole number ratio formula for ${H_2}{O_2}$ is $HO$.
Similarly, we can take the example of benzene having the molecular formula ${C_6}{H_6}$. The empirical formula for benzene is $CH$.
The compound that have same molecular as well as empirical formula is carbon monoxide i.e. $CO$. In case of carbon monoxide, the ratio of carbon and oxygen atoms is 1:1 thus it is already as simple as it can be, hence the empirical formula is $CO$ same as the molecular formula.

Note: Empirical formula can be calculated by following steps:
- First, we convert the mass of each element into moles by using molar mass of each element.
- Then, we divide each mole value by the smallest number of moles calculated.
- The divided value is rounded to the nearest whole number.
- The value obtained in the above step is the mole ratio of elements and is represented by subscripts in the empirical formula.