An empirical formula is a chemical formula that represents the simplest whole number ratio of atoms in a compound. It is obtained by analyzing the elemental composition of a compound, and expressing the elements in their simplest form. For example, the empirical formula for glucose, a simple sugar, is C6H12O6, which represents the fact that for every six carbon atoms, there are twelve hydrogen atoms and six oxygen atoms present in the molecule.
On the other hand, a molecular formula is a chemical formula that represents the actual number of atoms in a molecule. It provides more detailed information about the structure of a compound compared to the empirical formula. While the empirical formula only indicates the ratio of atoms in a molecule, the molecular formula gives the exact number of atoms of each element present.
For example, the molecular formula for glucose is also C6H12O6, but this represents the fact that there are exactly six carbon atoms, twelve hydrogen atoms, and six oxygen atoms present in the molecule. In this case, the empirical formula and the molecular formula are the same, but this is not always the case.
There are instances where the empirical formula and the molecular formula are different. This can happen when a compound contains multiple atoms of an element, or when the compound has a structure that is not represented by the empirical formula. For example, the empirical formula for cellulose, a complex carbohydrate found in plants, is C6H10O5, but the molecular formula is C12H22O11, which represents the fact that there are two molecules of the empirical formula present in each molecule of cellulose.
In conclusion, the empirical formula and the molecular formula are both important tools for understanding the chemical makeup of a compound. The empirical formula represents the simplest whole number ratio of atoms in a compound, while the molecular formula gives the exact number of atoms of each element present in a molecule. Understanding the difference between these two types of formulas is essential for correctly identifying and characterizing compounds in chemistry.