Lab Report #6

General Chemistry Lab I CHEM 1111.001 Experiment #3: Shedding Light on the Structure of the Atom Student’s name: Retha (Kaleigh) LaForge Lab partner(s) name: Richard Ramirez Date: 23 October 2023

Objectives/Goals : learn to use a basic spectroscope to observe the emission lines of a series of elements. You will also use your knowledge about the properties of light to calculate the energy and frequency associated with major transitions in an element. Safety Concerns: Some light sources (e.g. hydrogen and nitrogen lamps) may emit ultraviolet radiation, which can damage your eyes. The typical safety glasses will protect your eyes from the UV radiation, so keep your safety glasses on at all times. Follow all laboratory rules accordingly. Procedure/Methodology: Generation of calibration curve. Pointed the slit of the spectroscope toward the fluorescent light while looking through the diffraction grating. Recorded the color and its position on numbered grid. Used the given information and generated a regression line for use as a calibration curve as well as the calibration equation. Calculated the energy associated with the emission line of a sodium sample appearing at 5.9 in the grid line. Used calibration curve data to determine the wavelength of this sodium line. The literature value for the wavelength associated with the sodium line is 589 nm. Calculated the percentage error associated with the wavelength calculated. Converted the wavelength from the sodium emission line to the energy associated with this transition. Identified each sample by recording the line spectrum, using the calibration equation to convert each grid position to a wavelength, recorded the wavelengths on graph, and compared the line spectrum recorded to the set of known line spectra to identify each substance. Then using this information, created a scatter plot to represent the change in wavelengths for each grid position of each substance.

Calibration equation: y = 0.0062 x + 2.2039 x = y − 2.2039 0.0062 y = 5.9 (grid position) x = ( 5.9 − 2.2039 ) 0.0062 wavelength = x wavelength = 596.1 nm Percentage of error: literal wavelength of sodium 589nm % Error = ( measured − literal ) literal % Error = ( 596.1 − 589 ) 589 x 100 % Error = ¿ 1.2% Energy associated with transition: convert wavelength to change in energy convert ∆ E = ( planc k ' sconstant )( speed of light ) wavelength ∆ E = ( 6.63 x 10 − 34 J / s − 1 )( 2.998 x 10 8 m / s − 1 ) 596.1 nm ( ¿ m x 10 9 ) *All units cancel aside from J ∆ E = ( 6.63 x 10 − 34 J )( 2.998 x 10 8 ) ( 596.1 x 10 9 ) ∆ E = 3.33 x 10 − 19 Identification of samples Pink Sample Color Grid Position Wavelength (nm) Violet 4.2 322.0 Blue 4.8 418.7 Green 5.2 483.2 Yellow 5.9 596.1 Orange 6.1 628.4 Orange-Red 6.4 676.8 Red 6.8 741.3 Find Wavelength:

Calibration equation: y = 0.0062 x + 2.2039 x = y − 2.2039 0.0062 Y= grid position values x = 4.2 − 2.2039 0.0062 x = 322.0 nm x = 4.8 − 2.2039 0.0062 x = 418.7 nm x = 5.2 − 2.2039 0.0062 x = 483.2 nm x = 5.9 − 2.2039 0.0062 x = 596.1 nm x = 6.1 − 2.2039 0.0062 x = 628.4 nm x = 6.4 − 2.2039 0.0062 x = 676.8 nm x = 6.8 − 2.2039 0.0062 x = 741.3 nm Graphed each wavelength

Identified substance as Helium since the red and purple wavelength were closer in proximity to the accurate red and purple wavelength as Helium. Conclusion: The experiment yielded several different results. The calibration equation in the format of y-intercept = slope (x intercept) – b. The placement of line spectrums when observing different colors. Calculating the energy change of sodium, as well as its wavelength using the calibration equation, and the percentage of error. The percentage of error for the sodium analysis calculated was 1.2%. Lastly the result of identifying substance one, the yellow substance was revealed as

helium, and substance two, the pink substance was revealed as hydrogen when comparing graphed line spectrums. If I were to complete this experiment again, I would pay closer attention to the calibration of the spectroscope as it can cause a great deal of error, I would also use a more precise spectroscope to ensure accuracy, and precision in my results.