Measuring Manganese Using Spectrophotometry PreLab Assignment for Measuring Mang

Question

Measuring Manganese Using Spectrophotometry PreLab Assignment for Measuring Manganese Using Spectrophotometry List 3 health effects associated with the intake of excessive manganese: 2. 3. In absorption spectroscopy the amount of light absorbed by a given sample at a specific wavelength is proportional to what two factors: 1. 2. Suppose you need to do an absorption spectroscopy experiment using an orange colored solution. Approximately what wavelength(s) of light would be the worst to measure the absorbance at; what would be the best wavelength(s) of light to measure the absorbance at. Why? Explain your answers in one or two sentences. Worst wavelength(s): Best wavelength(s): Explain: Page 1 of 2

Explanation / Answer

Health effects associated with intake of excessive manganese,

1. hallucinations

2. nerve damage

3. forgethfulness

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In absorption spectroscopy, amount of light absorbed is proportional to,

1. path length of cell

2. Concentration

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For orange colored solutions, the wavelength of choice would be,

Worst wavelength 600 nm.

best wavelength 480 nm

The blue light is absorbed in this case as so the solution appears orange in color. This is according to the color wheel.

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2 Mn2+ is oxdized by 5 IO4-

Mn2+ present = 0.60 mg/ml

in 5 ml moles of Mn2+ = 0.60 x 5.0/55 = 0.055 mmol

KIO4 needed = 0.055 x 5/2 = 0.14 mmol

minimum mass of KIO4 needed = 0.14 x 230 = 31.4 mg

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Protein analysis

from the given data,

E = (0.138 - 0.046)/(0.039 - 0.013)

   = 3.54 M-1.cm-1

concetration of protein in diluted sample = 0.228 x 0.039/0.138

                                                                 = 0.064 M

concentration of protein in undiluted sample = 0.064 x 250/20 = 0.805 M

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