Chapter 6, Problem 47A

Interpretation Introduction

Interpretation :

Molecular formula of the compound with empirical formula CH₂O and molar mass between 89 and 91 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 C₃H₆O₃.

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 ${\text{CH}}_{\text{2}}\text{O=(12+2}\times \text{1+16)g=30 g}$ .

Molar mass of the compound is between 89 and 91 which can be taken as 90.

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

Thus 90= ${{\text{(CH}}_{\text{2}}\text{O)}}_{\text{n}}$ or $\text{n=}\frac{90}{30}\text{=3}$ .

Thus molecular formula is ${{\text{(CH}}_{\text{2}}\text{O)}}_3{\text{=C}}_{\text{3}}{\text{H}}_{\text{6}}{\text{O}}_{\text{3}}\text{.}$

Conclusion

Molecular formula of the compound is C₃H₆O₃.