---
title: "Racemic mixture vs meso compound"
subject: "Engineering Chemistry"
chapter: 9
key: "semester_2/engineering_chemistry:racemic-meso"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/racemic-meso
site: BCT Engineering
---

# Racemic mixture vs meso compound

Engineering Chemistry · Chapter 9: Stereochemistry

- Asked in: 2072 Asoj, 2 marks
- Video: [Meso Compound and Racemic Mixture I Isomerism I Particles Academy](https://www.youtube.com/watch?v=yzPhgoPvYT0) — Particles Academy ( English )
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/racemic-meso
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-9

## Question

Differentiate between racemic mixture and meso compound.

## Short answer

A racemic mixture is an equimolar mixture of two enantiomers, optically inactive due to external cancellation, and can be separated. A meso compound is a single achiral molecule with chiral centers but an internal plane of symmetry, permanently inactive and cannot be resolved.

## Answer

| Basis | Racemic mixture | Meso compound |
|---|---|---|
| Nature | Equimolar mixture of two enantiomers (d + l) | A single pure compound |
| Chiral centres | Each molecule is chiral | Has chiral centres but is achiral overall |
| Cause of inactivity | External compensation | Internal compensation (plane of symmetry) |
| Resolution | Can be separated into d and l forms | Cannot be resolved |
| Example | (±)-lactic acid, (±)-tartaric acid | meso-tartaric acid |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is a racemic mixture?
   A. An equimolar mixture of two enantiomers
   B. A single compound with a plane of symmetry
   C. A mixture of diastereomers
   D. A pure dextrorotatory compound
   Answer: A. Meso is a single pure compound. (Key point: Nature)

2. How does inactivity arise in a racemic mixture?
   A. Internal compensation
   B. No chiral centres exist
   C. External compensation between the two enantiomers
   D. Absorption of light
   Answer: C. Meso compounds show internal compensation. (Key point: Compensation)

3. Which can be resolved into d and l forms?
   A. Racemic mixture
   B. Meso compound
   C. Both
   D. Neither
   Answer: A. A meso compound is a single compound and cannot be resolved. (Key point: Resolution)

## Related in Engineering Chemistry

- [Enantiomers, racemic mixture, meso compound](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aenantiomers-racemic-meso) — Engineering Chemistry, chapter 9
- [Diastereomers and resolution of racemic mixture](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Adiastereomers-resolution-racemic) — Engineering Chemistry, chapter 9