First Report-Chem 4000.docx - CHEM 4000 Spring 2019 Jawad Chowdhury Statistical Nature of Data Unknown Methyl Red used A16 and B16 25th September 2019

First Report-Chem 4000.docx - CHEM 4000 Spring 2019 Jawad...

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CHEM 4000 Spring 2019 Jawad Chowdhury Statistical Nature of Data Unknown Methyl Red used : A16 and B16 25 th September 2019
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Table of contents: 1. Introduction 2. Experimental Observations 3. Data Observations and Results 4. Data Discussion 5. Conclusion 6. References 7. Appendix
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Introduction: There are a multitude of manners to identify the concentration of given unknown substances that we’ve done in previous classes; Acid-Base titrations come to mind. Properties of solutions that change with concentration also include density of the solution, conductivity, as well as the colour of the solution. Beer’s Law correlates intensity of the colour of the situation with its concentration. In most cases, using colour is much faster than doing titrations. The most tedious aspect of using colour is the formation of the calibration curve. When solutions of color are irradiated by white light, they absorb lights of different wavelength. This is due to the relationship between electron present in the molecule and its internal energy. If the right amount of energy is supplied using electromagnetic radiation to the molecules, the electrons can get agitated, leading to them jumping to higher levels of energy. When this happens, the particular energy of light, which corresponds to a particular wavelength or color, is absorbed and disappears. This, in turn, shows the remaining mixture of colours as non-white light. Beer’s Law is: A = εbc Where A is the absorbance of light by the solution, ε is the molar absorptivity, b is the pathlength of the light through the solution (a.k.a. the cell length) and c is the concentration of
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the solution. The wavelength at which absorbance is highest is the wavelength to which the solution is most sensitive to concentration changes. This wavelength is called λmax In this experiment, methyl red is used. It is an indicator dye that turns red in acidic solutions. It is also used to identify bacteria producing stable acids by mechanism of mixed acid fermentation of glucose (Clarke 1941).
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