UV-Visible lab report PDF

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Lab report for UV-Visible experiment...

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UV-Visible Spectrophotometry CHE 400L

September 17, 2018

Chan-yang Yang Augustine Mpemba

Purpose The purposes of this experiment are; 1) to understand the Beer-Lambert Law and absorption spectrum 2) to determine the concentration of a solution by measuring absorption. 3) to demonstrate the application of UV-visible spectrophotometry. Procedure Preparation

Cary 100 UV-Vis was used during this experiments. As the preparation of the lab, absorbance reading and sample spectrum running took place. The spectrum showed a significant deep between around 200 nm and 310 nm. The drop in the absorbance caused by the material of the cuvettes. The reference cuvette was quartz while the sample cuvette was glass. Part 1 and 2 The holmium oxide filter was inserted as sample for the next run of the first lab. Average time was set as 0.100 seconds, data interval 0.50 nm, and SBW 1.5 nm. Blank cuvette with air was used. Full range spectrum was used from 800.00 nm to 200.00 nm. When the holmium oxide filter spectrum was done, benzene was acquired for the second part of the lab. A matched pair of quartz cuvette was used. With pasteur pipette, one drop of benzene was carefully delivered into the cuvette. To get acute and precise peak, any contact of benzene with the cuvette wall was avoided. The cap was closed as the benzene was delivered and waited few minutes to have the vapor in the cuvette. The setting of average time 0.100 seconds, data interval 0.20 nm and range of 350.00 nm to 220.00 nm was used for benzene vapor sample. Empty blank was used as the background. To see effect of different bandwidth, four attempts with different SBW were proceeded. The tested bandwidths were 0.2, 0.5, 0.1, and 2.0 nm. Part 3 Preparation

For the analyzation of standard, conditional reagent was prepared by mixing Concentrated HCL (30 ml), 95% ethanol (100 ml), NaCL (75 g), glycerol (50ml) and DI water (300 ml) in 1-liter volumetric and mixed. 100 ppm standard sulfate solution was prepared by delivering Na2SO4 (0.1479 g) into 1-liter volumetric flask and diluting it to the mark. 5, 10, 15, 20, 25, 30, 35, and 40 ml of standard solution was delivered into eight 100-ml volumetric flasks and labeled from 5 to 40 ppm. Each flask was diluted to 100 ml. Analyzing Standards The 100 ml of 5 ppm sample and 5.0 ml of conditioning reagent was placed in a 250 ml Erlenmeyer flask with stirring rod. The solution was kept being stirred briskly. 0.2500 g of BaCL2 was added to the flask while the solution was being stirred. At exact 1 minutes, the solution was transferred into the sample cuvette and placed in the spectrophotometer. Setting of average time 0.100, SBW 1.0 and wavelength 420 nm was used. Absorbance was measured for 2-minute period and a maximum reading was obtained. The same procedure was repeated for the other 7 standards. Water Samples: Lake Ablin and mineral water 5, 10, 15, 20, 25, 30, 35, and 40 ml of water sample was delivered into eight 100-ml volumetric flasks and labeled. Each flask was diluted to 100 ml to get 5 to 40 % sample. 100 ml of 5 % sample and 5.0 ml of conditioning reagent were delivered into a 250-ml Erlenmeyer flask and stirred briskly. 0.2500 g of barium chloride was added to the flask while the flask was being stirred. At exact 1 minutes, the sample was delivered into the absorbance cuvette. Absorbance was measured for 2-minutes period with setting of average time 0.100, SBW 1.0 nm and wavelength 420 nm. The same procedure was repeated from the other 7 concentrations. The entire procedure was repeated for mineral water.

Water Sample: Tap water Water sample (100 ml) was placed in a 250-ml Erlenmeyer flask with 5.0 ml conditioning reagent. 0.2500g of BaCl2 was delivered into the flask while it was being briskly stirred. After exact one minute, the sample was transferred to the absorbance cuvette. Absorbance was measured for 2-minutes period with setting of average time 0.100, SBW 1.0 nm and wavelength 420 nm. Data and Result Part 1 Wavelength(Literal) 279.3 287.6 360.8 418.5 453.4 536.4 637.5

Tolerance ±1 ±1 ±1 ±1 ±1 ±1 ±1

Wavelength(Acquired) 279.0 287.5 360.5 418.5 453.5 536.0 637.5

Difference 0.3 0.1 0.3 0.0 0.1 0.4 0.0 (nm) Table 01. Holmium Oxide Filter Spectrum The sample data acquired was all within the tolerance compared with the literal value of spectrum of holmium oxide filter. The differences between literal and acquired values are varied between 0.0 nm and 0.4 nm and these differences may have caused because the data interval was 0.500 nm. If data interval setting was reduced to smaller than 0.500 nm, the most of result peaks would have been closer to literal value. Part 2 Part 3...