Investigation 20.docx - Investigation 20 How Much Cobalt is...

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Investigation 20: How Much Cobalt is in the Soil? Moses Habib, Abdullah Alazzam TA: Victoria Ton October 8. 2014 4:40 PM – 6:20 pm
Introduction: In this experiment, entitled “How much cobalt is in the soil”, the main goal was to measure the amount of cobalt (Co) in an unknown solution using the technique of spectroscopy. Using a colorimeter, which is basically a device used to measure the absorbance of light by a solution. Concentration is an important factor that affects the absorbency in a solution; the higher the concentration of a sample, the less light transmitted through, the higher the absorbency. The amount of light absorbed by different concentrations can be calculated using Beer-Lambert’s Law, which states that absorbance (A) is proportional to concentration (c) of a compound in a solution and the path length of a sample (b): (A=ebc) (e represents the constant molar absorptivity and b represents the thickness of the solution in the path of light). A standard curve is constructed to show the relationship between concentration and absorbance as this generates a straight line, which makes it easier to deal with. This can help identify and determine the amount of a substance in an unknown solution. Procedure: Materials: 0.1 M of Cobalt (II) Nitrate 0.06M of Cobalt (II) Nitrate Graduated Cylinder 2 Cuvettes Distilled Water Spectrometer Colorimeter Tissues Method:
Similar to the last lab in which the absorbance was discovered from the colored dyes.

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