Atomic Spectroscopy

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Atomic Spectroscopy Suzanne Rakes Chemistry 2 Lab Dr. Seelbinder February 19, 2002 Data The data in the optical rail graph shown above contains the plotted points of Mercury (series 1) and Krypton (series 2) line readings in mm. and their wavelength in nm. The mercury and krypton wavelengths were found by estimating where the colors were on the spectrum and referring to the handout that was given for the values. The line readings were taken from an average of the three or four-color bands on the continuum spectrum shown when looking through the optical rail spectroscope. Shown below is a chart of the line readings and average of the colors that were seen when looking through the optical rail.

Gaseous Mercury Left (mm) Average (mm) Right (mm) Orange 8.5. 8.65 8.8 Green 8 8.1 8.2 Violet 6 6.25 6.5 Gaseous Krypton Left (mm) Average (mm) Right (mm) Violet 6.2 6.35

6.5 Green 8 8.25 8.5 Orange 8.5 8.95 9 Hydrogen Left (mm) Average (mm) Right (mm) Green 7.1 7.05 7 Red 10 9.95 9.9 Violet 6.3 6.35 6.4 The Rydberg Equation graph shown above shows the 1/n2 value and the 1/lambda values and then given is the y equation. The 1/lambda is the inverse of the Hydrogen wavelengths. The hydrogen wavelengths were found by putting the line readings into the mercury and krypton slope equations given from excel. (Calculations shown below) Calculations (Refer to charts and graphs shown above) Mercury y = 59.375x + 64.789 59.375 x 7.05mm. + 64.789 = 483.4nm.

59.375 x 9.95mm. + 64.789 = 656nm.

59.375 x 6.35mm. + 64.789 = 442nm.

Krypton y = 60.942x + 46.972 60.492 x 7.05mm.+ 46.972 = 477nm.

60.492 x 9.95mm. + 46.972 = 653nm.

60.492 x 6.35mm. + 46.972 = 434nm.

Average of wavelengths 480.2nm.


438nm (Refer to Rydberg graph and chart shown above) Color 1/n2 1/lambda Red 1/9 = 0.111111111 1/655 E-9 = 1526717.56 Green 1/16 = 0.0625 1/480.2 E-9 = 2082465.64 Violet 1/25 = 0.04 1/438 E-9 = 2283105.02 Percent error = actual - theoretical / actual x 100 = % 1.076414 -1.096776 / 1.076414 x 100 = 1.89% (about 2% error) Discussion/Results The percent error was about 2%. Our wavelength values for Krypton and Mercury were estimated according to our handout of given wavelengths. They were very close to the actual wavelengths of Mercury and Krypton. This is known by looking at the percent error and seeing how close it is. The slope equations obtained from Mercury and Krypton was used to find the wavelengths for Hydrogen. This is also a reason we know the wavelengths were close to the actual wavelengths. You can also tell that this was a successful experiment by comparing the Rydberg Equation (-1.096776) to the equation given from excel calculations which was "“1.076414.

When looking at the fluorescent lamp through a square grid all of the colors of the spectrum were shown except orange. This could possibly be that the gas present in the fluorescent lamp gives off an orange color and that could be why orange was not seen. Then a normal light with colored coverings were observed. The colors seen when looking through the grid are: blue covering-all colors of spectrum shown, red covering-all colors shown, yellow covering-green, yellow, red, slightly purple, dark red covering- red, yellow, green, purple.

Note: Observations of the continuum spectrum are shown above in the table of Mercury, Krypton and Hydrogen. The bands of color observed are noted in this table.