B curious to see whether you could have determined

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: tion, you prepare a 10-mg sample of the partially racemized Asp from the skull sample in 10 mL of water and measure its optical rotation in a precision polarimeter in solution in a 1-dm cell. What observed optical rotation do you find for this sample? Show your work. Biot’s law is [a]observed = [a]20(concentration in g/mL)(cell length in dm) D The concentration in g/mL is 0.001, since a 10-mg sample was diluted into 10 mL. Therefore, for pure unracemized L-Asp, the expected observed rotation would be [a]observed = (+5 deg mL g–1 dm–1)(0.001 g mL–1)(1 dm) = 0.0050 degrees In a partially racemized sample, if y% is D-Asp, then 2y% of the optical activity of L-Asp MCMP 204 / Exam 2 / Spring 2012 ANSWERS Page 8 has disappeared, because the y% of D-Asp has negative rotation that cancels y% of the positive rotation of L-Asp. Therefore, for the 6/94 sample found here, the percent remaining optical activity is 100–2(6) = 88. Therefore, the observed optical activity of the partially racemized sample should be (0.88)(0.0050) = 0.0044 degrees....
View Full Document

This note was uploaded on 06/18/2012 for the course MCMP 204 taught by Professor Berkstrom during the Spring '08 term at Purdue University-West Lafayette.

Ask a homework question - tutors are online