An attempt at synthesizing a certain optically active compound resulted in a mixture of its enantiomers. the mixture had an observed specific rotation of 12.0°. if it is known that the specific rotation of the r enantiomer is –38.3°, determine the percentage of each isomer in the mixture.

Percentage of R enantiomer = 34.33 %

Percentage of S enantiomer = 65.67 %

Explanation:

The formula for the calculation of the Optical rotation is:

Given that:

For R enantiomer:

Let % = x %

Specific rotation = –38.3°

For S enantiomer:

% = 100  - x  

(2 enantiomers in mixture)

Specific rotation = 38.3° (Opposite direction of R enantiomer)

Given, Observed specific rotation of mixture = 12.0°

Thus,  

Solving for x, we get that:

x = 34.33 %

Percentage of R enantiomer = 34.33 %

Percentage of S enantiomer = 65.67 %

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.