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Why does specific rotation of plane-polarized light INCREASE with increased concentrations of the stereoisomer?

Answer 1

Because specific rotation is determined by concentration........

It has been a long time since I had to use a polarimeter, however, a cell of FIXED path length is filled with a KNOWN concentration of solution containing the analyte. The degree of optical rotation, #alpha#, depends on the path length of the cell, and also on the concentration of solution contained in the cell. Of course this is consistent with the fundamental principles of all spectroscopy: signal depends on the path length, and on the concentration of absorbing species within that path length.

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Answer 2

Elias Aguila

The specific rotation of plane-polarized light increases with increased concentrations of the stereoisomer due to the increased number of molecules present, resulting in a greater overall effect on the rotation of light passing through the solution.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.