Answer:
α = -0,885°
Explanation:
The specific rotation [α] is defined as:
[α] = α/ c×l (1)
Where α is the observed rotation, c is concentration in g/mL, and l is optical path length in dm.
A racemic mixture has no optical activity. As the solution of (R)-2-butanol is mixed with an equal volume of the racemic mixture the concentration of the original solution decreases twice. That is 1,72M/2 = 0,86M. This concentration in g/mL is:
0,86mol/L×[tex]\frac{1L}{1000mL}[/tex]×[tex]\frac{74,122g}{1mol}[/tex]= 0,0637 g/mL
Replacing in (1):
[tex]-13,9mL.g^{-1}.dm^{-1}=\frac{a}{0,0637g/mL*1dm}[/tex]
α = -0,885°
I hope it helps!
