Specific Rotation Calculator

Calculate the specific rotation of a substance based on wavelength, concentration, path length, and observed rotation

Input Parameters

Calculation Results

Calculation Formula

[α] = (α_observed × 100) / (λ × c × l)

Where:
[α] = Specific rotation
α_observed = Observed rotation (degrees)
λ = Wavelength (nm)
c = Concentration (g/mL)
l = Path length (dm)

Result

Specific Rotation ([α]):

Specific Rotation Calculator Usage Guide

Learn how to use the Specific Rotation Calculator and its working principles

What is Specific Rotation?

Specific rotation is a measure of the optical activity of a substance at a specific wavelength, concentration, and temperature. It is defined as the observed rotation of the plane of polarized light divided by the product of the path length of the sample and the concentration of the substance.

How to Use This Calculator

  1. Enter the wavelength of light used for measurement in nanometers (typically in the visible range of 400-700 nm).
  2. Input the concentration of the substance in grams per milliliter (g/mL).
  3. Specify the path length of the sample cell in decimeters (dm). Common path lengths are 1.0 dm or 10 cm.
  4. Record the observed rotation in degrees (°).
  5. Click the "Calculate" button to compute the specific rotation.

Applications

Specific rotation is commonly used in the pharmaceutical industry to determine the purity of chiral compounds, in sugar analysis, and in the quality control of various optically active substances. It is an important parameter in the characterization of polymers, amino acids, and other optically active molecules.

Important Notes

  • The specific rotation is highly dependent on the wavelength of light used, so it is crucial to specify the wavelength when reporting the value.
  • The temperature at which the measurement is taken can also affect the specific rotation, so it should be noted if different from the standard temperature (usually 20°C).
  • For accurate results, ensure that the concentration is expressed in g/mL and the path length in dm.