1. Tardigrade
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  3. Chemistry
  4. The optical rotation of the α -form of a pyranose is +150.7° , that of the β -form is +52.8° . In solution an equilibrium mixture of these anomers has an optical rotation of +80.2° . The percentage of the α -form in equilibrium mixture is

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Q. The optical rotation of the $\alpha $ -form of a pyranose is $+150.7^\circ $ , that of the $\beta $ -form is $+52.8^\circ $ . In solution an equilibrium mixture of these anomers has an optical rotation of $+80.2^\circ $ . The percentage of the $\alpha $ -form in equilibrium mixture is

NTA AbhyasNTA Abhyas 2020Organic Chemistry – Some Basic Principles and Techniques

Solution:

Let the percentage of $\alpha $ -form be X

$150.7\left(\right.X\left.\right)+52.8\left(\right.1-X\left.\right)=+80.2$

$150.7X+52.8-52.8X=+80.2$

$97.9X=27.4$

$X=0.279=0.28$

$\approx 28\%$