Category CH P06 Chirality: The Relationship Between Angle of Rotation and

Concentration

Abstract Chirality is the property of a molecule such as glucose to be non-

superimposable on its mirror image. Chiral molecules also have the unique

property of rotating plane-polarized light, which is light whose waves

oscillate in the same plane (emitted from sources such as computer

screens). The change in the orientation of the plane of polarization by a

chiral molecule is known as the angle of rotation. In this experiment I

constructed a polarimeter (using a laptop computer screen, a rotating

base, polarized sunglasses, and a digital camera), with the purpose of

determining the relationship between the angle of rotation and the

concentration of glucose solutions. I did so by utilizing 0% (water), 25%,

50%, and 100% glucose solutions. I hypothesized that the angle of rotation

and the concentration would be inversely related, with the angle

decreasing as concentration increased. Each solution was tested using

the polarimeter to determine the extent to which each solution rotated the

light’s plane of polarization.

The results suggest a direct relationship between the concentration of a

solution containing chiral molecules and its corresponding angle of rotation,

which disproved my hypothesis. This finding has many applications in

manufacturing, mainly in determining the concentration of chiral molecules

such as carbohydrates, amino acids, and drugs (such as penicillin). By

using a large-scale version of the polarimeter described here, the process

could be expanded to an industrial scale.

Bibliography 1) All of Science, by Allan R. Glanville 2) "Stereochemistry" from the Gale

Encyclopedia of Science.

http://go.galegroup.com/ps/retrieve.do?sgHitCountType=None&sort=RELEV

ANCE&inPS=true&prodId=GVRL&userGroupName=catholiccenhs&tabID=T0

03&searchId=R1&resultListType=RESULT_LIST&contentSegment=&search

Type=AdvancedSearchForm&currentPosition=1&contentSet=GALE|CX341

8502185&&docId=GALE|CX3418502185&docType=GALE&role= 3)

Introduction to Stereochemistry, by Kurt Mislow
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