A solution containing 0.4 g/mL of a pure S enantiomer is a 1 dm polarimeter rotates plane polarized light by +5.6°.What is the rotation of a solution containing 0.8 g/mL of the S enantiomer in the same polarimeter?
A)+5.6°
B)+11.2°
C)+2.8°
D)+1.4°

Question

Quizplus · Accepted Answer

Specific rotation is directly proportional to the concentration of a solution. Therefore, the rotation of the solution containing 0.8 g/mL can be calculated using the following formula:

[α] = α / lc

where [α] is the specific rotation, α is the observed rotation, l is the path length (1 dm), and c is the concentration in g/mL.

Using the given data, we can calculate the specific rotation of the solution containing 0.4 g/mL:

[α] = +5.6° / (1 cm × 0.4 g/mL) = +14°

Therefore, the rotation of the solution containing 0.8 g/mL can be calculated as:

α = [α] × l × c = (+14°) × (1 dm) × (0.8 g/mL) = +11.2°

Thus, the answer is B, +11.2°.

A Solution Containing 0