Suppose that a 0.2 g/mL solution of (S) - ibuprofen in a 2 dm long cell rotates plane-polarized light + 10°. What is the specific rotation for (S) - ibuprofen?

+25°

Explanation:

The formula for calculatin the specific rotation, α, is:

α=αobs: (c*l)

αobs being the rotation observed

c is being the concetration (g/mL)

l being the path length (dm)

So it ends up being:

α=+10° / (0.2 g/mL*2 dm) = + 10°*ml/0,4g*dm

α=25°