Difference Between Empirical Formula and Molecular Formula


As we know that a substance is a composition of different atoms. We have to represent this substance with the help of atomic symbols. The representation of a substance with the help of atomic symbols is known as the chemical formula of that substance. These chemical formulas are divided into two types. The first type of the chemical formulas is known as molecular formula and the second type of the chemical formulas is known as the empirical formula. Here, we will explain the difference between the molecular formula and the empirical formula.
Difference Between Empirical Formula and Molecular Formula

What is Molecular Formula?

A chemical formula which represents the total number of atoms in each compound is known as the molecular formula. The molecular formula of butene is C4H8. This molecular formula of butene shows that in a butene compound, there are four carbon atoms and there are eight hydrogen atoms. The molecular formula of benzene is C6H6. This molecular formula of benzene shows that it has 6 carbon atoms and 6 hydrogen atoms. The molecular formula of glucose is C6O6. The molecular formula of glucose shows that it has 6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms.
Empirical Formula and Molecular Formula of glucose

What is the Empirical Formula?

The empirical formula of a compound represents the simplest whole-number ratio of the atoms that are presented in this compound. It means that we have to know the total number of atoms in a compound before finding its empirical formula. As we know that the molecular formula of benzene is C6H12O6. The simplest whole-number ratio of its atoms 6:12:6 is 1:2:1. Therefore, the empirical formula of benzene is CH2O. Similarly, the molecular formula of Di-Sulphur Di-Oxide is S2O2. The simplest whole-number ratio of its atoms 2:2 is 1:1. Therefore, its empirical formula is SO.
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Difference Between Empirical Formula and Molecular Formula

As molecular formula and empirical formula are two different types of the chemical formulas. Therefore, the main difference between them is given below;
1.      Molecular formula and empirical formula show different kinds of the representation of the atoms. In a molecular formula, we represent the total number of atoms in each compound. On the other hand, with the help of empirical formula, we represent the simplest whole-number ratio of the atoms in a compound.
2.      The molecular formulas of different compounds are different but the empirical formulas of different compounds can be identical. The molecular formulas of glucose, ribose, acetic acid are C6H12O6, C5H10O5, and C2H4O2. These examples of molecular formulas show that each compound has a different molecular formula. On the other hand, when we find the simplest whole-number ratios of all the atoms of these compounds, we know that all of these compounds have a similar molecular formula which is CH2O.
3.      With the help of molecular formula, we can represent the structure of the elements of a compound. On the other hand, with the help of empirical formula, we just express the elements which are forming this compound.
4.      Both molecular and empirical formula of a compound can be similar. For example, CH2O is the molecular formula of formaldehyde. As we can’t simplify the atoms of this compound, therefore, CH2O is also the empirical formula of formaldehyde.
5.      We don’t use the empirical formula in the chemical reactions but we are using molecular formulas in the chemical reactions. Its reason is that in a chemical reaction, we have to balance atoms on both sides of the reaction. If we are using the empirical formula, it is difficult for us to balance both sides of the equation.
6.      We can derive the empirical formula of a compound by deriving weight percentages of the elements in the compound. On the other hand, we derive the molecular formula of a compound from its empirical formula.
7.      To write the name of a compound, we give preference to the molecular formula over the empirical formula. Its reason is that we can’t represent more than one compounds with the help of a molecular formula. On the other hand, an empirical formula can represent more than one compounds.
8.      The molecular formula of Hydrogen Peroxide is H2O2. On the other hand, its empirical formula is HO. Its reason is that the simplest whole-number ratio between its atoms 2:2 is 1:1.

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