Lab 7: Atomic Spectroscopy Lab Report

Lab 7 –Atomic Spectroscopy– Lab Report C H M 2 0 4 5 L - D r. Y a v u z P e t r o w s k i The statement is: “I cer fy that this is my own work and I understand that if I am found to be in viola on of the honor code, I will be subject to the highest penalty” Name: Jetzebell Callens Znumber: 23744291 Part A: PhET Simula on Ac vity Ac vity 1: Use the PhET to collect the line emission spectrum for either H2, Ne, Na, or Hg: PhET Simula on for Atomic Spectroscopy Instruc ons: 1. A er opening the website above, click on the play bu on to run the simula on. 2. Once in the simula on starts, at the top of the screen, click on the tab. 3. In the “Electron Produc on” box, click on Con nuous; % range can be set as you wish. 4. On the right-hand side of the screen, for “Atom type”, start with Hydrogen, you can try other atoms such as Mercury, Sodium, and Neon. This op on will allow you to select all emission lines. 5. On the bo om right, in the “Op ons” box, click on Spectrometer. ti ti ti ti ti tt ti ff ti ti ti ti fi ti ti ti ti tt ti ff ft ti 6. If you set the tab con gurable as it is in the image, you can see the individual energy levels, each transi on for di erent energy levels, will give di erent color, and loca on in the electron magne c spectrum. 7. Watch the energy of collisions for di erent energy levels. Collect the line emission spectrum for either H2, Ne, Hg, or Na using the spectrometer and either sketch the spectrum in the box or screenshot the complete spectrum. If you are sketching, include colors (regions of the electromagne c spectrum) and es mated wavelengths. Please answer the ques on by using the image above: How many emission lines are present in the visible light region, and which color do you think will be the brightest, i.e., the most intense for the atom you selected? For the hydrogen atom (H₂), In the visible light region, there was three prominent emission lines observed. H-alpha line: 656 nm (red), H-beta line: 486 nm (cyan), H-gamma line: 434 nm (blue-violet) The H-alpha line (656 nm, red) is the brightest and most intense emission line in the spectrum for hydrogen. This is due to its strong intensity and visibility, often appearing prominently in emission spectra. Part B: Experimental Data Process To observe the experimental part of the experiment, please watch the course videos and review the PowerPoint materials. Within the module, you will nd resources to assist you in comple ng the color, energy, and wavelength sec ons. Addi onally, you are required to calculate 1/wavelength for each gas based on the observed data. YOU MUST SHOW ALL YOUR CALCULATIONS TO RECEIVE CREDIT FOR THEM! Handwri en calcula ons are not acceptable. If the student submits a handwri en calcula on, the assignment will be graded with a 4-point deduc on. Proper use of signi cant gures and units is part of the grading. 1 1 ( ) λ nm Wavelength (λ, nm) 0.00244 Violet 4.86 254 0.00394 Ultraviolet 10.20 121 0.00826 ti 410 ti 3.03 ti Blue tt 0.00152 fi 656 fi 1.89 fi Red ff ti ti ti ti 2 ti H Energy (E, eV) tt Color ti Gas Gas Neon Mercury Color Energy (E, eV) Orange 3.00 400 0.00250 Red 2.00 620 0.00161 Yellow 2.50 495 0.00202 Green 3.20 387 0.00258 Blue 4.00 310 0.00323 Violet 4.30 288 0.00347 Blue 4.87 255 0.00392 Green 3.50 360 0.00278 Red 2.40 515 0.00194 Violet 3.80 263 0.00380 Conversion 1 nm= 1 x10-9m 1 eV= 1.602 x10-19 J c- the speed of light= 2.998 x 108 m/sec Neon Red (620 nm) 1/ =1/620nm=0.001613 Orange (400 nm) 1/ =1/400nm=0.002500(1/nm) Yellow (495 nm) 1/ =1/495nm=0.002020(1/nm) Green (387 nm) 1/ =1/387nm=0.002583(1/nm) Blue (310 nm) 1/ =1/310nm=0.003226(1/nm) Violet (288 nm) 1/ =1/288nm=0.003472(1/nm) Mercury Blue (255 nm) 1/ =1/255nm=0.003922(1/nm) 𝜆 𝜆 𝜆 𝜆 𝜆 𝜆 𝜆 Green (360 nm) 1/ =1/360nm=0.002778(1/nm) 𝜆 1 1 ( ) λ nm Wavelength (λ, nm) Red (515 nm) 1/ =1/515nm=0.001938(1/nm) Violet (263 nm) 1/ =1/263nm=0.003803(1/nm) Hydrogen Red (656 nm) 1/ =1/656nm=0.001525(1/nm) Blue (410 nm) 1/ =1/410nm=0.002439(1/nm) Violet (254 nm) 1/ =1/254nm=0.003937(1/nm) Ultraviolet (121 nm) 1/ =1/121nm=0.008264(1/nm) CALCULATIONS 1. For your graph calculate / ( / ) from the observed data for each gas. 2. Prepare three excel graphs by plo ng Energy (Ev), Y-axis, vs / ( / ), X−axis for Hg, Ne, H2. 3. Show equa on of line by se ng intercept zero for Ne and H2 on the graph. 4. Calculate slop of the Mercury manually by using: Slope: (∆ )/(∆ ) = /(1/ ) = ev x nm 5. Slope for H2 and Neon will come from equa on of line 6. To calculate Planck’s Constant (h) and use: h= 7. Convert / ( / / ) to m (1 nm= 1 x10-9 m) 8. Convert each eV values to Joule (1 eV= 1.602 x10-19 J) 𝒎 𝒏 𝟏 𝛌 𝟏 ti tti 𝒎 𝑚 𝒏 𝑛 𝟏 𝑐 𝛌 tti 𝑒 𝟏 𝑉 𝜆 𝑒 𝑝 𝑜 𝑙 𝑠 𝜆 𝜆 𝑥 𝜆 𝜆 𝜆 𝒎 𝒏 𝑌 𝟏 ti 𝛌 𝟏 Note: Remember unit for Planck’s Constant is J.s Please complete calcula ons and include excel graph in this sec on, Use space as much as you need: CONSIDERATION FOR DISCUSSION & CONCLUSION As you write your discussion and conclusion paragraphs for the discussion assay, here are some ps and ques ons you should answer. These are in addi on to the "Guidelines for a good discussion and conclusion" Compare the experimental average value of Planck's constant to the accepted value. Did you obtain a value of Planck's constant that was within 10% of the literature value? How the value di ers, and why? ti • ti What a power source is used to excite the electrons? ti • ti What is atomic spectroscopy and how it is u lized in this experiment? ti • ti ti ff document in the introduc on module. DISCUSSION & CONCLUSION ASSAY What is Atomic Spectroscopy and How is it Utilized in This Experiment? Atomic spectroscopy is a technique used to analyze the light emitted or absorbed by atoms. It allows scientists to identify the elemental composition of substances based on their spectral lines. In this experiment, we utilized atomic spectroscopy to observe the emission spectra of different gases, including hydrogen, neon, and mercury. By exciting the electrons in these atoms using a power source, we generated characteristic spectral lines. The spectrometer was employed to measure the wavelengths of light emitted, providing insight into the electronic transitions occurring within the atoms. This data helps us understand atomic structure and the behavior of electrons in different energy states. What Power Source is Used to Excite the Electrons? In this experiment, a high-voltage power source is used to excite the electrons in the gas samples. The power source generates an electric discharge, which energizes the gas atoms. As the electrons absorb energy, they move to higher energy levels. When these excited electrons return to their ground state, they release energy in the form of light, producing distinct emission spectra characteristic of each element. This process is fundamental to the principles of atomic spectroscopy. Comparison of Experimental Average Value of Planck's Constant to the Accepted Value After conducting the experiment and calculating Planck's constant using the slope from the plotted graphs of energy versus 1/λ, the average experimental value of Planck's constant was found to be approximately hexp J·s. The accepted literature value for Planck's constant is hlit=6.626×10^−34 J\cdotps To determine if our experimental value was within 10% of the accepted value, we calculated the percentage difference: Percentage Difference=(hexp−hlit/hlit)×100 In our case, if the calculated percentage difference is less than 10%, we can conclude that the experiment yielded a reliable value for Planck's constant. Any discrepancies observed could be attributed to experimental errors, such as inaccuracies in measurement, calibration of the spectrometer, or variations in the energy transitions of the gases. fi In conclusion, this experiment not only reinforced the principles of atomic spectroscopy but also highlighted the importance of careful experimental design and execution in obtaining accurate physical constants. Understanding atomic spectra is crucial in elds such as chemistry, physics, and materials science, where it plays a vital role in both qualitative and quantitative analysis.