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

Question

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 (A) 28% (B) 32% (C) 68% (D) 72%

Tardigrade Admin · Accepted Answer

Let the percentage of α -form be X 150.7(.X.)+52.8(.1-X.)=+80.2 150.7X+52.8-52.8X=+80.2 97.9X=27.4 X=0.279=0.28 ≈ 28 %

Q. The optical rotation of the $α$ -form of a pyranose is $+ 150. 7^{\circ}$ , that of the $β$ -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 $α$ -form in equilibrium mixture is

28%

32%

68%

72%

Let the percentage of $α$ -form be X

$150.7 (X) + 52.8 (1 - X) = + 80.2$

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

$97.9 X = 27.4$

$X = 0.279 = 0.28$

$\approx 28%$

Q. 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

28%

32%

68%

72%

Let the percentage of α -form be X 150.7(X)+52.8(1−X)=+80.2 150.7X+52.8−52.8X=+80.2 97.9X=27.4 X=0.279=0.28 ≈28%

Q. The optical rotation of the $α$ -form of a pyranose is $+ 150. 7^{\circ}$ , that of the $β$ -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 $α$ -form in equilibrium mixture is

Let the percentage of $α$ -form be X

$150.7 (X) + 52.8 (1 - X) = + 80.2$

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

$97.9 X = 27.4$

$X = 0.279 = 0.28$

$\approx 28%$