Chapter 6, Problem 47A

Interpretation Introduction

Interpretation :

Molecular formula of the compound with empirical formula CH₂ and molar mass 84 must be found out.

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 47A

The molecular formula is C₆H₁₂.

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.

Molar mass of ${\text{CH}}_{\text{2}}\text{=(12+2}\times \text{1)g=14 g}$ .

Molar mass of the compound is 84 g.

Now Molecular formula= ${{\text{(CH}}_{\text{2}}\text{)}}_{\text{n}}.$

Thus 84= ${{\text{(CH}}_{\text{2}}\text{)}}_{\text{n}}.$ or $\text{n=}\frac{84}{14}\text{=6}\text{.}$ .

Thus molecular formula is ${{\text{(CH}}_{\text{2}}\text{)}}_6{\text{=C}}_6{\text{H}}_{12}\text{.}$

Conclusion

Molecular formula of the compound is C₆H₁₂.