Chapter 23, Problem 63A

Interpretation Introduction

Interpretation:

The molecular formula, molecular weight and functional groups present in glucose and fructose should be compared and contrast.

Concept introduction:

The compounds having similar chemical formula but different structures are known as isomers.

The compounds having similar chemical or molecular formula but different connectivity is known as constitutional isomers.

Molecular formula of a compound contains chemical symbols of each element with subscripts (numeric) which represents the number of atoms of each element present in the compound.

Molecular weight is defined as the addition of atomic masses of each atom present in the compound.

Functional group is defined as the group of atoms or bonds present in a compound which is responsible for the chemical reaction(s) of the compound.

Answer to Problem 63A

The molecular mass and molecular weight of both glucose and fructose is same.

Fructose contains ketone functional group whereas glucose contains aldehyde functional group.

Explanation of Solution

Glucose consists of single unit of sugar which can’t be hydrolyzed into simpler molecule. Glucose is obtained by the photosynthesis process and also found in plants.

Fructose consists of single unit of sugar which can’t be hydrolyzed into simpler molecule.

Glucose and fructose are structural isomers of each other implies they have same molecular formula that is ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ but have different structures. Since, the molecular formula of both glucose and fructose is same, thus, the molecular weight of glucose and fructose is also exactly same.

Molecular formula of glucose and fructose = ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$

Molecular weight of glucose and fructose

= $\text{6}\times \text{12 g/mole +12}\times \text{1}\text{.00784 g/mole + 6}\times 16\text{ g/mole}$

= $180.094\text{ g/mole}$

Now, the structure of glucose and fructose is:

Glucose

Fructose

Glucose and fructose both have six carbon atoms and five alcohol groups. But, fructose contains ketone (-C=O) functional group whereas glucose contains aldehyde (-CHO) functional group.