Objective : To measure an absorbance value of the different colour solutions by using Spectrophotometry
Spectrophotometry involves the use of a spectrophotometer. A spectrophotometer is a photometer (a device for measuring light intensity) that can measure intensity as a function of the color, or more specifically, the wavelength of light (nm). The instrument also can be use on biological sample such as chlorophyll pigments and suspended E.coli.
Spectronic 20-Genesys 20
iii. Glass rod
iv. Volumetric flask 50 ml
vi. Retort stand
vii. Distilled water
viii. Orange soda pop (F&N)
1. The soda pop was poured into a beaker and stirred to remove the carbonate substance. 2. The soda pop was pipette into a burette.
3. 5 ml of soda pop was dropped into a volumetric flask and was diluted with distilled water. 4. Step 3 was repeated for 10 ml, 15 ml, 20 ml, and 25 ml of soda pop. 5. The cuvette was filled with ¾ samples.
Measuring the spectrum
1. The spectrophotometer was turned on.
2. The wavelength was set at 600 nm.
3. 0% of transmittance (%T) was adjusted. (Dark current adjusted-by using non-fill cuvette). 4. A cuvette was filled with distilled water and inserted in the sample compartment with the line face the front. The top was closed. 5. 0 absorbance and 100% transmittance were adjusted by holding the water cuvette. The cuvette was removed and set aside without emptying it. 6. The other cuvette was filled with soda solutions.
7. The soda filled cuvette was placed at the sample compartment and the absorbance value was read.
Solution concentration (ml)| Transmittance| Absorbance| | 1| 2| 3| Mean| 1| 2| 3| Mean|
5| 61.5| 58.7| 60.1| 60.1| 0.211...