A solution of a chiral complex is 80 percent of the (+) form and 20 percent of the (-) form…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A solution of a chiral complex is percent of the (+) form and percent of the (-) form. The pure (+) form rotates plane-polarised light by under the conditions of the experiment. Find the excess of the (+) form. Find the rotation the solution gives.
Need a reminder? The key ideaShow
A complex is chiral when it has no plane of symmetry. Stereoisomers = geometrical isomers + mirror-image pairs. The observed rotation of a mixture is the rotation of the pure (+) form times the excess of one form, divided by 100 percent.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Excess. percent.
Step 2. Rotation. The solution rotates light by , in the same direction as the (+) form.
Check. If the solution were racemic, the rotation would be . If it were pure (+), it would be . The answer lies between them.
Answer: a percent excess of (+), and a rotation of .
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