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Optical Rotation 1. a. The specific rotation, [] D , for (+)-alanine is + 8.5 .

ID: 891445 • Letter: O

Question

Optical Rotation

1.

a. The specific rotation, []D, for (+)-alanine is +8.5. What is the observed rotation for a solution of 1.7 g of (+)-alanine in 10 mL of water in a sample tube having a pathlength of 10 cm?

Answer: _________ degrees

b. The observed rotation of a solution of 1.2 g of a compound in 10 mL of water is -5.3 degrees. If the pathlength is 10 cm, what is the specific rotation of the compound?

2.

a. The specific rotation, []D, for (-)-malic acid is -27. What is the observed rotation for a solution of 1.5 g of (-)-malic acid in 10 mL of water in a sample tube having a pathlength of 10 cm?

Answer: ________ degrees

b. The observed rotation of a solution of 1.4 g of a compound in 10 mL of water is +1.3 degrees. If the pathlength is 10 cm, what is the specific rotation of the compound?

3.

a. The specific rotation, []D, for (-)-malic acid is -27. What is the observed rotation for a solution of 1.2 g of (-)-malic acid in 10 mL of water in a sample tube having a pathlength of 10 cm?

Answer: ______ degrees

b.   The observed rotation of a solution of 1.4 g of a compound in 10 mL of water is -10 degrees. If the pathlength is 10 cm, what is the specific rotation of the compound?

Explanation / Answer

There are multiple questions here. . i am allowed to answer only 1 at a time. I will answer all part of question 1st question for you

1.

a)
formula tobe used:

specific rotation= rotation / (l*rho)
l is length in dm
rho is density in g/mL

here rho = density = mass/volume = 1.7g/10 mL = 0.17 g/mL
l = 1 dm

specific rotation= rotation / (l*rho)
8.5 = rotation / (1*0.17)
rotation= 1.445 degree

Answer: 1.445 degree

b)
here
rho = density = mass/volume = 1.2g/10 mL = 0.12 g/mL
l = 1 dm

specific rotation= rotation / (l*rho)
                  = -5.3 / (1*0.12)
                  = -44.17
Answer: -44.17 degree

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