Question

(5 questions) Data: Consider the data below for a Beer's Law calibration curve for an aqueous orange nye solution that has mas 450 nm. The solutions used were translucent. The data was collected using a 1.20cm wide test tube cuvette, using 2 = 450 nm. Trial Concentration (M) Absorbance Percent Transmittance 1 0 .0030 0.153 70.3 0.0060 0.312 48.8 0.0090 0.465 34.3 0.0120 0.627 23.6 0.0150 0.771 16.9 For each of the following errors/changes, indicate whether a repeat of the experiment with only that change would produce absorbance readings that would: a) be lower, b) stay the same, c) be higher, or d) frequently be lower and frequently be higher than the data above. (pick one letter a, b, c, ord for each change) The cuvette is changed to a 2.54cm wide cuvette. 2. The wavelength is changed to 550 nm. i The experiment is repeated, but with a different 1.20cm cuvette. This other cuvette contained an unreactive impurity that makes the solution cloudy. A standard of chloromethane gas is prepared with a concentration of 0.0140M. Its absorbance in the infrared is measured in a 1.20cm cuvette with a light source set to a wavelength of 14000nm. The absorbance is found to be 0.250. 4. What is the molar absorption coefficient, e, of this gas at 14000nm? What is the concentration of a different sample of chloromethane gas, which under the same conditions had an absorbance that is approximately one half of the absorbance of the first solution: A = 0.250/2 = 0.125?

Answer 1

At 140ohm wahe longth Ataorbance (A) = 0.250 ette length ) = 1.2007 conch (C) = 0.0140M Acc to Bearls Lambert lave A=EU - 0 Where A Abhorbance . Et molar absorpticity 1. Coefficient 0250 = EX0-0140 M X 1.200m e euwat te length com &= 0.250 Mtant 1 ct conch of the sample solution 0.0140 X 1020 &= 14.8mlamt Molar abrorlatulty Coefficiout Conch of different sample of chloromethane gas ? Ginen Absorbance Half of the aborrbance of the first solution = 6250 = 0-125 &= 1.48 Mlimt la 1- 20cm From Egh - A = Ece 0.125 = 14.8 mil cant cx1.2004 c= 0.125 M 14,8 x 1.20 c= 0.0070M conch of Romble of chloromethane Scanned w gas