Q37 / 160 · TS EAMCET 2009 · Chemistry

The concentration of an organic compound in chloroform is $6.15 \mathrm{~g}$ per $100 \mathrm{~mL}$ of solution. A portion of this solution in a $5 \mathrm{~cm}$ polarimeter tube causes an observed rotation of $-1.2^{\circ}$. What is the specific rotation of the compound?

  • A
    $+12^{\circ}$
  • B
    $-3.9^{\circ}$
  • Correct answer
    C
    $-39^{\circ}$
  • D
    $+61.5^{\circ}$

Solution

$\begin{aligned} {[\alpha] } & =\frac{[\alpha]_{\text {observed }}}{l \times C} \\ & =\frac{-1.2}{5 \times \frac{6.15}{1000}}=-39^{\circ}\end{aligned}$

Hence, the correct answer is option: 'C'.

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