Calculate Specific Rotation of Alanine in Ethanol Solution

What is the specific rotation of alanine in ethanol solution?

Given data: A solution made of 3.85 g of alanine in ethanol to a total volume of 15.6 mL at 25°C is placed into a 120 mm polarimeter tube for a measurement, and the observed rotation is 4.29°.

Specific Rotation Calculation:

The specific rotation of alanine in ethanol at 25 degrees Celsius can be calculated using the formula: [α] = α / (l * c).

To calculate the specific rotation of alanine in ethanol, we need to consider the observed rotation, the path length, and the concentration of the solution. In this case, the observed rotation is 4.29°, the path length is 120 mm (1.2 dm), and the concentration is 3.85 g/15.6 mL = 0.2468 g/mL.

Therefore, we can calculate the specific rotation as follows:

[α] = 4.29° / (1.2 dm * 0.2468 g/mL)

[α] = 14.49° g/mL·dm

So, the specific rotation for alanine in ethanol solution at 25 degrees Celsius is 14.49° g/mL·dm.