Chapter 21, Problem 1STP

Interpretation Introduction

Interpretation:

The term that best describes L-Alanine and D-Alanine with respect to each other needs to be determined.

Concept introduction:

Two mirror image representations are possible for a molecule having chiral center in its structure. If the mirror images are non-superimposable to each other then, they are said to be optical isomers.

Answer to Problem 1STP

The correct option is (c): optical isomers.

Explanation of Solution

A molecule is said to be chiral molecule when all the attached groups to central carbon atom are different and lacks in plane of symmetry in the molecule. The molecules having chiral centres show optical isomerism as there are two mirror image representations possible for a molecule having chiral center in its structure and if the mirror images are non-superimposable to each other then, they are said to be optical isomers.

The structure of L-Alanine is:

Now, drawing the mirror image of L-Alanine as:

Since, the mirror image, D-Alanine is not superimposable to each other so, they are optical isomers of each other.