# CHEM 113 UND Physical Chemistry Problem Set

2023/01/12Chem 113A Problem Set 01: Lectures 01–03
Due 2023/01/19 @ 10 PM
We encourage you to work with others in the class on the problem set, but the end product must
represent your effort. Formulas and constants can be found on the last page.
Part 1 (To be done in Discuss Section. If you do not finish it in section, please finish at home)
a. Two of the many classes of stars are called blue dwarfs and red dwarfs because of their apparent
colors. Here’s the visible spectrum and its corresponding wavelengths:
Which class of stars have higher temperature? Explain your reasoning. Which class of stars is
brighter?
b. In spectroscopy, we use terms like “redshift” and “blueshift” to describe how the spectrum
changes. Redshift means the peak of the spectrum is shifting to longer wavelength (becoming
redder); and blueshift means the peak of the spectrum is shifting to shorter wavelength
(becoming bluer). For a blackbody, as temperature increases, does its spectrum blueshift or
redshift?
pg. 1
Problem Set 01
Due 01/09
c. The figure below shows the solar spectrum at sea level (i.e., the intensity of sun light as a function
of wavelength measured at sea level). The dotted curve shows the extraterrestrial spectrum (i.e.,
measured outside the atmosphere). Estimate the temperature of the sun. (Hint: You’ll have to
use one of the two laws we learned in the lecture, Wien’s Displacement Law or Stefan-Boltzmann
Law)
pg. 2
Problem Set 01
Due 01/09
2) Photoelectric Effect
a. 300-nm light is shone on a piece of calcium. The ejected electron has a de Broglie wavelength of
1.10 nm. What is the work function of calcium?
b. What is the maximum wavelength (i.e. minimum frequency) of light needed to eject an electron
from calcium?
pg. 3
Problem Set 01
Due 01/09
3) de Broglie wavelength The Tolbert group in the Chemistry Department uses X-ray diffraction to
examine the structures of their polymer films. The X-ray beam they use in their experiments has an
energy of 12.75 keV (1 eV = 1.602×10-19 J).
a. If we want to use a beam of electrons instead of X-ray, what should be the velocity of the
electrons so that would produce the same diffraction pattern?
b. What is the kinetic energy of the electron?
c. Why do you think that they used electrons instead of photons?
pg. 4
Problem Set 01
Due 01/09
Part 2 (Take-home)
1) Bohr Model
a. In class, we identified the 𝑛 = 2 → 𝑛 = 1 transition …
Calculate the frequencies for the following transitions and label them on the figure:
𝑛 = 4 → 𝑛 = 1, 𝑛 = 3 → 𝑛 = 2, and 𝑛 = 4 → 𝑛 = 2
Do you observe a trend? Label all the transitions without doing additional calculations.
pg. 5
Problem Set 01
Due 01/09
b. For a hydrogen atom with its electron in the 𝑛 = 1 energy level, what wavelength of light would
remove (eject) the electron? (i.e., what wavelength of light would ionize ground state hydrogen?)
(Hint: removing electron means putting the electrons infinitely far away from the nucleus. What
value of 𝑛 would cause an electron to be placed infinitely far away from the nucleus?)
pg. 6
Problem Set 01
Due 01/09
2) Uncertainty Principle
a. What is the uncertainty of the momentum of an electron if we know its position is somewhere in
a 52.9 pm interval (the radius of the 𝑛 = 1 orbit for the Bohr model)?
b. How does the value compare to the momentum of an electron in the first Bohr orbit?
c. Based on your answers in parts a & b, how much confidence can we have in the position and the
momentum of an electron in the first Bohr orbit?
pg. 7
Problem Set 01
Due 01/09
3) Origin of Q.M. Complete the following chart
Experiments/Theory
Significance
Bohr’s explanation for
Einstein’s explanation
for photoelectric effect
Bohr’s atomic model
Two-slit experiment
with electrons
pg. 8
Problem Set 01
Due 01/09
Formulas and constants:
𝑐 = 𝜈𝜆
𝐸 = ℎ𝜈
𝜆max 𝑇 = 2.90 × 10−3 m ⋅ K
𝑅 = (5.6697 × 10−8
𝜆=
J
) 𝑇4
m2 K 4 s

𝑚v
𝐾𝐸 = ℎ𝜈 − Φ
1
𝐾𝐸 = 𝑚v 2
2
𝑟=
4𝜋𝜀0 ℏ 2
𝑛
𝑚𝑒 𝑒 2
v=
𝑛ℏ
𝑚𝑒 𝑟
𝑚𝑒 𝑒 4 1
𝐸=− 2 2 2
8𝜀0 ℎ 𝑛
𝑐 = 2.9989 × 108 m/s
ℎ = 6.626 × 10−34 J ⋅ s
ℏ = 1.055 × 10−34 J ⋅ s
Charge of an electron, 𝑒 = 1.60 × 10−19 C
Mass of an electron, 𝑚𝑒 = 9.11 × 10−31 kg
𝜀0 = 8.854 × 10−12 F/m
pg. 9

Don't use plagiarized sources. Get Your Custom Essay on
CHEM 113 UND Physical Chemistry Problem Set
Just from \$13/Page
Calculate the price
Pages (550 words)
\$0.00
*Price with a welcome 15% discount applied.
Pro tip: If you want to save more money and pay the lowest price, you need to set a more extended deadline.
We know how difficult it is to be a student these days. That's why our prices are one of the most affordable on the market, and there are no hidden fees.

Instead, we offer bonuses, discounts, and free services to make your experience outstanding.
How it works
Receive a 100% original paper that will pass Turnitin from a top essay writing service
step 1
Fill out the order form and provide paper details. You can even attach screenshots or add additional instructions later. If something is not clear or missing, the writer will contact you for clarification.
Pro service tips
How to get the most out of your experience with Writall
One writer throughout the entire course
If you like the writer, you can hire them again. Just copy & paste their ID on the order form ("Preferred Writer's ID" field). This way, your vocabulary will be uniform, and the writer will be aware of your needs.
The same paper from different writers
You can order essay or any other work from two different writers to choose the best one or give another version to a friend. This can be done through the add-on "Same paper from another writer."
Copy of sources used by the writer
Our college essay writers work with ScienceDirect and other databases. They can send you articles or materials used in PDF or through screenshots. Just tick the "Copy of sources" field on the order form.
Testimonials
See why 20k+ students have chosen us as their sole writing assistance provider
Check out the latest reviews and opinions submitted by real customers worldwide and make an informed decision.
Nursing
Outstanding
Customer 455459, October 8th, 2022
good
Customer 454567, December 2nd, 2020
Other
I got an A in this project.
Customer 453877, February 6th, 2020
Nursing
Great content, resources, and turn around!
Customer 454991, November 2nd, 2021
Hello Can I please get a copy of a plagiarism report? Thanks, Dan
Customer 454899, September 30th, 2021
Law
Amazing work! 10/10
Customer 455105, December 5th, 2021
Film & Theater studies
Amazing job. Thank you
Customer 454983, November 24th, 2021
Other
Amazing job. Hellen Is fantastic
Customer 454983, December 9th, 2021
IT, Web
good job
Customer 455223, December 21st, 2021
Nursing
Thank you!
Customer 454959, February 6th, 2022
Nursing
very satisfied!
Customer 454099, June 15th, 2020
Nursing
very satisfied
Customer 454099, May 22nd, 2020
11,595
Customer reviews in total
96%
Current satisfaction rate
3 pages
Average paper length
37%
Customers referred by a friend