Polarized Light and Sucrose Sol

A spiral rainbow is observed in the solution of common sugar.

Scientific name: The dependence of specific rotation on wavelength in solution of optically active material is demonstrated.

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Safety

Wear eye protection goggles.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reagents

  1. Sugar
  2. Water

Step-by-step instruction

1.Fill the cylinder with sucrose solution. 2.Place the cylinder on a polarizer. 3.Put an analyzer polarizing filter on the top of the cylinder. 4.Turn on the light source. 5.The color will change as analyzer is rotated.

Scientific background

When the plane of polarized light passes through the cylinder filled with sucrose solution a spiral rainbow is observed perpendicular to the cylinder. When white light passes through the polarizer the extent of rotation of light depends on its wave length. Short wavelengths are rotated more than longer wavelengths. Since the wave length of light determines its color the variation of color with distance is observed. When a second polarizing filter is placed on the top of the cylinder and is rotated, the range of transmitted color is shown. This dependence of specific rotation on wavelength is called optically rotatory dispersion. The ability of sucrose to display optical rotation with change in light wavelength is caused by structural features of the molecule. Sucrose consists of glucose and fructose units bounded with glycosidic linkage. Both glucose and fructose are optically active and could rotate the plane of linearly polarized light. Glucose rotates it to the right, fructose – to the left. This effect arises from the twist within the monomers leading to the existence of optical isomers or enantiomers. In enantiomers the sequence of atom and bond arrangement are the same but the molecules could be presented as two mirror images of one another.

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Published on 05 August 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst