Full set of Notes with Fill-Ins - San Jose State University

Chem 155 Unit 15 275 of 31614. Cyclohexanone has a strong absorption peak at 5.86μmand at this wavelength a linear relationship exists betweenabsorbance and concentration.a. Calculate the frequency of this mode in cm -1 .b. Identify the part of the molecule responsible (the groupfrequency) for the absorbance at this wavelength.This is the ‘carbonyl’ or ketone symmetric stretch.c. Suggest a solvent that would be suitable for a quantitativeanalysis of cyclohexanone at this wavelength.CCl 4 , CHCl 3 or tetrachloroethylened. A solution of cyclohexanone (2.0 mg/mL) in the selectedsolvent has an absorbance of 0.40 in a cell with a pathlength of 0.025 mm. What is the detection limit for thiscompound under these conditions, if the noise associatedwith the spectrum of the solvent is 0.001 absorbanceunits.A=εbC calibration slope = εb10 45.86= 1706 cm − 1εbAC− 1⎞ ⎟⎠0.402.00 mg0.2 mg3s ⋅⎛b= ⎜C⎝ mLmm⋅mL3⋅0.001⎛⎝0.2⋅⎜mgmL⎞⎟⎠=− 10.015 mgmLPage 275 of 316