What is the relationship between the specific rotation of (2S ,3S)-dibromopentane and (2R, 3R)-dibromopentane? A) It is different in magnitude and opposite in sign
B) it is equal in magnitude and have the same sign
C) it is zero
D) it is equal in magnitude but opposite in sign
E) It is not possible to predict the specific rotation

D) it is equal in magnitude but opposite in sign

Explanation:

The compounds (2S ,3S)-dibromopentane and (2R, 3R)-dibromopentane are a pair of enantiomers.

Enantiomers are stereoisomers that that are mirror images of each other and rotate plane polarized light. The magnitude of rotation of plane polarized light is known as specific rotation of the compound measured in degrees.

Enantiomers have the same magnitude of specific rotation but opposite in sign. This is  because one enantiomer rotates plane polarized light to the left while the other rotates plane polarized light to the right.

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation:

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