Soecific rotation

Question

24 gm of optically pure tartaric acid is dissolved in water to make 240 ml solution. It is kept in 20 cm polarimeter tube and plan polarised light is passed through it to produce rotation of - 2.4 ∘ . 2.4∘. Answer the following questions : If origihnal solution is diluted by 2 times and length of polarimeter is increasexd four times of previous length. What will be the specific rotation?optically-tartaric-dissolved-water-make-solution-kept-polarimeter-tube-polarised-light

Answer 1

 [α] = \(\frac{Q}{c\times l}\)

Where,  [α] = specific solution

Q = rotation

C = Concentration

l = length of polarimeter tube (dm)

Concentration of tartaric acid = 24/240 = 1/10 g/ml

[α] = \(\frac{-2.4}{\frac{1}{10}\times\ 2}\)

[α] = -12°

Specific rotation does not depends on concentration and length of polarimeter tube.

∴ Hence, specific rotation of solution = -12°c