How To Use -

This calculator is designed to calculate the specific rotation([a]) of a chiral compound given several variables. This may come in handy for people who also built polarimeters. The observed angle is measured in degrees(a) using the polarimeter. The path-length(l) is in decimeters(dm). The path-length is the distance from the bottom of the cell to the meniscus of the fluid layer. Usually this is 1dm(10cm) in length. if you built your own this may vary. The concentration(c) is in grams per mililiter(g/mL). The calculator will accept fractions but please leave out the units. The resultant specific rotation is in degrees.

Specific Rotation Calculator -

TI83 - Source Code -

:ClrHome
:Menu("POLARIMETRY","SPECIFIC ROTATION",A,"GRAMS",B)
:
:Lbl A
:Prompt θ,L,G,V
:θ/(L*(G/V))->S
:Disp "SPECIFIC ROTATION",S
:Goto Z
:
:Lbl B
:Prompt S,θ,L,V
:(θ*V)/(S*L)->G
:Disp "GRAMS: ", G
:Goto Z
:
:Delvar θ
:Delvar S
:Delvar G
:Delvar V
:Delvar L

Additional -

In other cases it may be neccesary to calculate the concentration of the solute(g/mL), from the observed rotation(*), knowing the path-length(dm) and the specific rotation(*) for the given pure chiral compound. I have not made a javascript calculator for this yet. This may be a 5 minute project for the future. If you are interested in how this is done re-arrange the formula. Or if you understand basic calculator code. In the TI-83 Source Code section I do have it set up to solve for grams in the solution. Not sure if this is common practice but it is how I plan to calculate concentration with my polarimeter.