D has an observed rotation of +0.22° in a A 0.160 M solution of an enantiomerica
ID: 555992 • Letter: D
Question
D has an observed rotation of +0.22° in a A 0.160 M solution of an enantiomerically pure chiral com 1-dm sample container. The molar mass of the co is 144.0 g/mol (a) What is the specific rotation of D? b) What is the observed rotation if this solution is mixed with an equal volume of a solution that is 0.160 M in L, the enantiomer of D? Number deg mL g dm 9.55 Number deg (c) What is the observed rotation if the solution of D is diluted with an equal volume of solvent? (d) What is the specific rotation of D after the dilution described in part (c)? Number Number deg mL g dm e) What is the specific rotation of L, the enantiomer of (f) What is the observed rotation of 100 mL of a solution that contains 0.01 mole of D and 0.005 after the dilution described in part (c)? mole of L? (Assume a 1-dm path length.) Number Number deg ml g dm Previous Give Up & View Solution e Check Answer Next Exit HintExplanation / Answer
a)
concentration = 0.160 x 144 = 23.04 g / L = 0.02304 g/mL
observed rotation = + 0.22 o
specific rotation = observed rotation / l x concnetration
= 0.22 / 1 x 0.02034
specific rotation = 9.55 deg .mL / g.dm
b)
equial volume and equal concnetrations of solutions mixed , racemic mixure formed.
observed rotation = 0 deg
c)
volume doubled , then concentration is halved.
c = 0.02304 / 2 = 0.01152
observed rotation = 9.55 x 0.01152 x 1
observed rotation = 0.11 deg
d)
specific rotation is uneffected by dilution
specific rotation = 9.55
e)
specific rotation of L = - 9.55
f)
moles= 0.01 - 0.005 = 0.005
concentration = 0.005 / 0.1 = 0.05 M
= 0.05 x 144 / 1000
= 0.0072
observed rotation = 0.0072 x 9.55 x 1
observed rotation = 0.069
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