The principals of spectrophotometry and the absorption spectrum of coloured solutions Essay

Submitted By Rach-Martin
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Pages: 3

The principals of spectrophotometry and the absorption spectrum of coloured solutions.

Abstract: In this experiment, spectrophotometry was used to investigate how much a chemical substance absorbs light. The experiment involved measuring out a chemical, using the spectrophotometer to measure wavelength and make a calibration curve. The mixture was analysed found the maximum wavelength to absorbance of the chosen chemical was 820nm. This technique that was used was an effective way of investigating the absorbance verse concentration spectrum of chemicals.
Introduction: Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity by measuring the intensity of light. In addition a wave length is defined as the distance between one peak and the next wave and are measured in nanometres (nm). Furthermore frequency is the number of time a wave length passes a particular point per second and is measured in hertz (hz). Hence this experiments aimed to understand the principals of spectrophotometry, to use a VIS spectrophotometer, to obtain an absorption spectrum of a coloured solution, to construct a calibration curve of absorbance verses concentration and to determine the concentration of an unknown. It was hypnotised that the chosen chemical would have a high wavelength to absorbance rate.
Method: Firstly the materials needed were: 6 testubes, distilled water, chosen substance, graduated pipettes, pipette filter, vortex mixer, curvets, spectrophotometer, distilled water, tissues and a beaker. In the preparations for experiment Cu(H20)4 which was blue also was copper consists in the wavelength range of 740 nm- 860 nm. In each test tube was allocated a volume of solution and a volume of distilled water. The spectrophotometer was set at 740nm for solution c which was CuSO4 and increase wavelength by 10nm and continue until the solution reaches 860nm. Finally record the wave length and abs.
Standard Number
Volume of Solution C: Copper
Volume of distilled water
1
0
10.0
2
2.0
8.0
3
4.0
6.0
4
6.0
4.0
5
8.0
2.0
6
10.0
0

Calculations: C1V1 = C2V2
0.050 x 0 / 10 = 0
0.050 x 2 / 10 = 0.01
0.050 x 4 / 10 = 0.02
0.050 x 6 / 10 = 0.03
0.050 x 8 / 10 = 0.04
0.050 x 10 / 10 = 0.05
Results: when beginning the experiment the wavelength of the spectrophotometer was set at 740nm and continued until 860nm shown in the…