abs lab - Purpose: The purpose of this experiment was to...

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Purpose: The purpose of this experiment was to use a spectrometer to determine the concentration of a unknown nickel solution. This was achieved by making a series of standard solutions and plotting a calibration curve and then using this information to determine the concentration of the unknown solution. Procedure: Calibrating the Instrument: It is important to turn on the spectrometer and let the instrument warm up for at least twenty minutes. The spectrometer must be set to the appropriate wavelength; in this case, the wavelength was set to 395nm, max absorbance of nickel. With no cuvette in the instrument, set the transmittance to 0%T this was done by using the left hand knob. Place a cuvette ~half filled with DI water, this was the reference blank, in the instrument sample holder and align the cuvette. The top of the holder must be shut at all times except when loading or unloading samples, this is to prevent stray light from entering the instrument. Use the right hand knob to set the readout to 100% transmittance, zero absorbance. Remove the blank. The display should read zero percent transmittance. If it does not the calibration must be repeated. The Absorption Spectrum: This information was provided: Unknown Color Wavelength Ni Green 395nm Co Red 525nm Cu Blue 625nm Possible unknowns and the maximum absorption wavelength Absorbance and Concentration: Using the 0.2M, nickel solution standard solutions were prepared. This was done by measuring 3ml and then 7ml of 0.2M stock solution each in a graduated cylinder and then filling to 10ml with DI water the two standard solutions each have a total volume of 10ml. The concentration of each of the two stock solutions were calculated using V conc M conc = V dil M dil . The 2 standard solutions and a 10ml of distilled water and 10ml of 0.2M stock solution were used. Make sure the wavelength is still set to 395nm. Use the same cuvette for each solution making sure to rinse cuvette first with DI water and then with the solution. Read %T for each of the four samples using the spec 20. Plot the concentration on the x-axis versus absorbance on the y-axis, making sure the %T has been converted to absorbance, for each of the standard solution. The graph should be a best-fit straight line to show the linear relationship between the absorption and the
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This note was uploaded on 01/30/2012 for the course CHEMISTRY 211 taught by Professor Keithdavies during the Spring '10 term at George Mason.

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abs lab - Purpose: The purpose of this experiment was to...

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