Copy of 5CL Pre-Lab 8 Submission Template - S23v2

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University of California, Los Angeles *

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5C

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Chemistry

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Feb 20, 2024

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pdf

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5

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Q1: Draw a schematic of the Bohr model of the hydrogen atom, with a nucleus consisting of a single proton and the n=1, n=2, n=3, and n=4 orbitals of the electron. Indicate which of these orbitals corresponds to the ground state. Draw an arrow representing the transition of the electron from the ground state to the first excited state. 2 n = 4 n = 3 n = 2 n = 1 -> Selectron t
Q2: Calculate the first 4 electron energy levels of the hydrogen atom. Calculate the energy difference between the n=1 level and the n=2 level. In the transition from n=1 to n=2 (drawn in Q1), does the electron gain or lose energy? The energy of hydrogen atom’s energy level can be expressed by E=-13.6/n^2 eV. For energy of n=1 level, E1= -13.6/1=-13.6eV. E2=-13.6/4=-3.4eV. E3=-13.6/9=-1.51eV. E4=-13.6/16=-0.85eV. Energy Difference: E2-E1=-3.4-(-13.6)eV=10.2eV The electron gains energy from n=1 to n=2 3
Q3: Are all energy levels equally spaced with respect to n? If not, do they become more or less closely spaced as n increases? Draw a new figure of 4 horizontal lines where each horizontal line corresponds to one energy level. Place the horizontal lines vertically to scale such that they are spaced accurately according to their energy, and label your lines corresponding to n=1, n=2, etc. The energy levels are not equally spaced with respect to n. They become more closely spaced as n increases. 4 Using this diagram, identify the largest energy transition between two adjacent energy levels. Calculate this energy difference and the corresponding frequency and wavelength of the emitted photon. Identify the largest energy transition that can occur between any two levels in your diagram. Calculate the energy for this transition along with the corresponding wavelength of the emitted photon. The largest energy transition between two adjacent energy levels is between n=1 and n=2. =1 n = 4 n = 3 n 2 -n 1 7 & Eiz = 10 . ZeV The largest energy transition between any two levels occurs between n = 1 and n = 4 (10 . 2) (1 . 6 x10-1) = hf & E , 4 = 12 . 75 eV f = 2 47x 1015 hE (12 . 75) (1 0x10-19) = hf f = 3 . 08x 1015 Hz x = 12 = 121 . 57nm 11 = 140 12 . 75= 97 . 25 um
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Q4: Calculate and list all transition energies up to n=4. Given that our spectrometer is built for visible light with wavelengths between 400 nm and 750 nm, which of these six hydrogen transitions do you expect to be able to see in your spectrometer? E12 = -3.4-(-13.6)eV =10.2eV E23 = -1.5-(-3.4)eV = 1.9eV E34 = -0.85-(-1.5)eV = 0.65eV E13 = -1.5-(-13.6)eV = 12.1eV E14 = -0.85-(-13.6)eV = 12.75eV E24 = -0.85-(-3.4)eV = 2.55eV 5 1931-42 - 4 sall) in) a I =97 . 25nm = 486 . 27nm will be able to 2 see these je two transitions
Q5: How might you determine if hydrogen or mercury gas is present in your fluorescent bulb, given that you’ve already measured the hydrogen and mercury spectra and know their transition peak energies? We can use the spectrometer and fiber optic cable to measure the light from the hydrogen gas bulb and the mercury gas bulb. The wavelength and color will allow us to distinguish the light. Using this, we can determine the amount of photons in each wavelength. We will then compare the photon spectrum from each trial. The spectrometer will record the peaks for these light sources. If we find that the spectrums are similar to the CFL bulb then we can determine that there is hydrogen or mercury in the bulb. 6