What is the expected observed rotation of a 9.1 x 10-5 M solution of compound X? Note: compound X has a specific rotation of [α]D20 = -49o and a molecular weight of 235.2 g/mol. In addition, the path length of the cell used to take the polarimetry measurement was 5.0 cm.
To calculate the expected observed rotation of a solution, we need to use the formula:
α = [α] × c × l
Where:
α is the observed rotation in degrees
[α] is the specific rotation of compound X in degrees per decimeter (given as -49°)
c is the concentration of the solution in moles per liter (M)
l is the path length of the cell in decimeters (given as 5.0 cm, which is equal to 0.05 dm)
First, let's convert the concentration to moles per liter (M):
9.1 x 10^-5 M solution means there is 9.1 x 10^-5 moles of compound X for every liter of solution.
Next, let's substitute the values into the formula:
α = (-49°) × (9.1 x 10^-5 M) × (0.05 dm)
Now, let's calculate the expected observed rotation:
α = -49° × 9.1 x 10^-5 × 0.05
α ≈ -2.2495 x 10^-4 degrees
Therefore, the expected observed rotation of the 9.1 x 10^-5 M solution of compound X is approximately -2.2495 x 10^-4 degrees.