Chapter 6, Problem 33A

Interpretation Introduction

Interpretation :

The role of empirical formula of a compound must be explained. The way in which the molecular formula of a compound is different from the empirical formula needs to be explained.

Concept Introduction :

Empirical formula of a molecule is the smallest unit which is repeated in the molecule.

Molecular formula of a compound is the representation of the molecule with the number of different atoms present in the molecule.

Molecular formula $\text{=empirical formula×n}$ where n is any positive integer like 1, 2, 3 and so on.

Answer to Problem 33A

Empirical formula of a compound represents the smallest repeating unit. Molecular formula is the multiple of an empirical formula. When molecular formula and empirical formula are not same then molecular formula represents more number of different atoms in a compound.

Explanation of Solution

The molecular formula can be found from the empirical formula using the following relationship.

Molecular formula $\text{=empirical formula×n}$ where n is any positive integer like 1, 2, 3 and so on.

Now when n=1, then molecular formula will be same as empirical formula.

For example formaldehyde has empirical formula as CH₂O which is also the molecular formula.

In other cases molecular formula is bigger than empirical formula. For example glucose has empirical formula CH₂O and molecular formula C₆H₁₂O₆. It is clear that in molecular formula there are 6 CH₂O units.

Conclusion

Empirical formula is defined and the difference between empirical formula and molecular formula is given.