Question

The observed rotation of 2.0 g of a compound in 50 mL of solution in a polarimeter tube 20 cm long is +138°. What is the specific rotation of the compound?

Answer 1

+1725

Step-by-step explanation:

The specific rotation can be calculated using the formula:

• Specific Rotation = Observed Rotation / (l * C)

Where l is the path length in decimeters (20 cm / 10), 2 dm; and C is the concentration of the compound in mg/mL (2.0g / 50mL), 0.04 g/mL.

Putting the data we're left with:

• Specific Rotation = +138 / (2 * 0.04) = +1725