Question

Determine if each of the following statements about chiral molecules is True or False and select the best answer from the dropdown menus.
True or False: All R stereocenters are dextrorotatory.
True or False: Chiral centers in organic molecules will have 4 different groups attached to a carbon.
True or False: A racemic mixture has an optical activity of 0.
True or False: Normal linear amines can be chiral centers.
True or False: Compound C has an optical activity of 0.
True or False: If the R isomer of a molecule has an optical rotation of + 25.7 degree then the S isomer of the molecule will have an optical rotation of -25.7 degree.
True or False: A CN is higher priority than a CH2OH.
True or False: All molecules with chiral centers are optically active.
True or False: To have an enantiomer a molecule must have at least two chiral centers.
True or False: Chiral molecules are always optically active.
True or False: A CH2CH2Br is higher priority than a CH2F.
True or False: Meso molecules with two stereocenters have a R,S configuration.
True or False: Diastereomers have the same physical properties except in a chiral environment.
True or False: Compound H has an optical activity of 0.
True or False: A C=C double bond is higher priority than a -CH(CH3)2.

Answer 1

Answer:

See explanation

Explanation:

-) True or False: All R stereocenters are dextrorotatory.

The absolute configuration is based is in specific rules that are not related to the ability to deflect polarized light. FALSE

-) True or False: Chiral centers in organic molecules will have 4 different groups attached to a carbon.

A chiral carbon by definition is a carbon with 4 groups. TRUE

-) True or False: A racemic mixture has an optical activity of 0.

In a racemic mixture, we have equal amounts of enantiomers, and this cancels out the optical activity. TRUE

-) True or False: Normal linear amines can be chiral centers.

In primary amines, we have 2 hydrogens. Therefore all the groups can not be different. So, is TRUE

-)True or False: Compound C has an optical activity of 0.

We need to know the structure of the compound

-)True or False: If the R isomer of a molecule has an optical rotation of + 25.7 degree then the S isomer of the molecule will have an optical rotation of -25.7 degree.

If we have the exact opposite (as we have in this case) the magnitud of the optical activity value will remain and the sign will change. TRUE

-)True or False: A CN is a higher priority than a CH2OH.

In this case, a carbon is directly bonded to the chiral carbon. The carbon on CN is bonded to a nitrogen atom and the carbon on CH2OH is bonded to an oxygen. So, the CH2OH will have more priority because O has a higher atomic number. FALSE

-)True or False: All molecules with chiral centers are optically active.

We can have for example mesocompounds in which the optical activity is canceled out due to symmetry planes. FALSE

-)True or False: To have an enantiomer a molecule must have at least two chiral centers.

A pair of enantiomers is made between at least 1 chiral carbon. Enantiomer R and enantiomer S. FALSE

-)True or False: Chiral molecules are always optically active.

We can have racemic mixtures or mesocompounds with chiral carbons but without optical activity. FALSE

-)True or False: A CH2CH2Br is higher priority than a CH2F.

The "Br" atom is bonded in the third carbon (respect to the chiral carbon) and the "F" atom is bonded to the second carbon. Therefore CH2F has more priority than CH2CH2Br. FALSE

-)True or False: Meso molecules with two stereocenters have a R,S configuration.

On the compounds with R and S configuration at the same time can have symmetry planes so, we will not have optical activity. TRUE

True or False: Diastereomers have the same physical properties except in a chiral environment.

All diastereomers have the same physical properties. TRUE

True or False: Compound H has an optical activity of 0.

We have to have the structure of the compound.

True or False: A C=C double bond is higher priority than a -CH(CH3)2.

In the case of C=C, we can say that is equivalent to two carbon bonds without hydrogens. Therefore C=C has higher priority. TRUE