Transcript Mac

Experiment 2. Inversion of Sucrose
We use a polarimeter (shown to
right) to monitor the time-dependent
changes in the angle of rotation of
polarized light from a sodium-D lamp.
The null point is obtained by
turning the handle slowly until the two
halves of the image grow equally
faint, as illustrated crudely in the
movie.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
(Here the handle has been
turned through the null point
and then back again.)
2
The scale on the polarimeter is
equipped with a vernier, similar to that
on the barometer (Expt. 1). Here the
reading is –6.1°.
The polarimeter tubes have
different-sized fittings on the two
ends, requiring different
windows. Take care to use the
correct window in each case!
3
Make sure that you understand clearly the concept of mutual dilution,
as covered in Study Problems 5 and 6. You will start each run by mixing a
measured volume of sugar solution with a measured volume of acid
solution. The initial concentrations of both in the run will be determined
by their prepared concentrations and their mutual dilution on mixing.
Come to class with your plans for preparing these different solutions
already worked out in detail. The volume of the polarimeter tubes is ~15
mL, so you will want each mix to contain at least ~20 mL.
Clean up all spillage at the end of the day: We don’t want the next
day’s teams sticking to the table!