Chem 111 Final PSU Study Guide
Exam with Actual Answers 2025-2026
Updated.
Exp. 2 - Spectroscopy - Answer
Define Spectroscopy - Answer Study of the interactions of electromagnetic radiation with
matter
Explain the difference between a line and continuous spectrum, and give an example of each
source of light - Answer Continuous spectrum contains all frequencies within a region of the
electromagnetic spectrum.
eg. sun
Line spectrum contains only certain frequencies.
eg. neon lamp
What kind of energy transitions were observed in this experiment? - Answer Balmer Series
(380 - 750 nm)
Describe what is meant by the term "white light," and know the wavelength range that white
light covers. List the colors of the spectrum from the highest to the lowest frequency. - Answer
Small band of radiation that can be seen by the human eye (400 - 800 nm). Includes the colors
red, orange, yellow, green, blue, and violet.
Explain the purpose of the "discharge tube" in this experiment. - Answer The discharge tube
contains H gas. The voltage source runs a current (electrons) through the discharge tube,
exciting the electrons in the gas. H's emission spectrum can then be seen but it is only excited to
certain levels so you can only see certain frequencies.
Explain the effect on the spectrum of changing (a) the slit width and (b) the distance from the
source of light. - Answer (a) changes the width of the spectral lines viewed through
spectroscope.
(b) changes the intensity of the light.
Outline in a few sentences how you calibrated your spectroscope. - Answer Viewed a light
, If you are given the wavelengths of light observed by a particular student for the hydrogen
emission spectrum you should be able to (a) determine the frequencies and the energies
associated with these wavelengths, (b) be able to use the Bohr equation to calculate the
wavelenths expected for the Balmer series of the hydrogen atom, (c) be able to quantitatively
compare results and Bohr's - Answer (a) c = (lambda)*v
(b) E = hv
(c) E = hv/(lambda)
E = Rh[(1/h)i^2 - (i/h)f^2]
Exp. 3 - Small-Scale Techniques - Answer
Explain the complementary nature of absorbed/observed colors. - Answer Depending on the
wavelength, colors are absorbed or observed. Low wavelengths absorb violet and high
wavelengths absorbed. Each wavelength observed color is opposite its absorbed.
What is the fundamental reason why a substance absorbs visible light? - Answer It depends
on the number of interactions between photons and the absorbing molecules.
Describe the technique of calorimetry. - Answer Uses solutions of known concentrations of a
light absorbing substance, in order to compare the light absorption of an unknown solution.
Concentration can be obtained when a color match is found.
What process removes the energy from excited food dye molecules in aqueous solution? -
Answer Solvent molecules bumping billions of times per second against the excited food
molecules.
Be able to use the dilution equation given in this experiment to solve dilution problems. -
Answer CiVi = CfVf
Be able to describe the observations of OTO with tap water and water passed through the Brita
filter. Explain. - Answer When tap water was reacted, the solution turned yellow due to high
chlorine ion concentration. The Brita water turned a slightly lighter shade of yellow due to the Cl
ions being removed because it stuck to the activated carbons which have tiny pores so there is a
high surface area to react.
Be able to calculate a standard deviation by hand for a given data set. - Answer sum([(xi-
x)^2/N-1]^1/2)
Exam with Actual Answers 2025-2026
Updated.
Exp. 2 - Spectroscopy - Answer
Define Spectroscopy - Answer Study of the interactions of electromagnetic radiation with
matter
Explain the difference between a line and continuous spectrum, and give an example of each
source of light - Answer Continuous spectrum contains all frequencies within a region of the
electromagnetic spectrum.
eg. sun
Line spectrum contains only certain frequencies.
eg. neon lamp
What kind of energy transitions were observed in this experiment? - Answer Balmer Series
(380 - 750 nm)
Describe what is meant by the term "white light," and know the wavelength range that white
light covers. List the colors of the spectrum from the highest to the lowest frequency. - Answer
Small band of radiation that can be seen by the human eye (400 - 800 nm). Includes the colors
red, orange, yellow, green, blue, and violet.
Explain the purpose of the "discharge tube" in this experiment. - Answer The discharge tube
contains H gas. The voltage source runs a current (electrons) through the discharge tube,
exciting the electrons in the gas. H's emission spectrum can then be seen but it is only excited to
certain levels so you can only see certain frequencies.
Explain the effect on the spectrum of changing (a) the slit width and (b) the distance from the
source of light. - Answer (a) changes the width of the spectral lines viewed through
spectroscope.
(b) changes the intensity of the light.
Outline in a few sentences how you calibrated your spectroscope. - Answer Viewed a light
, If you are given the wavelengths of light observed by a particular student for the hydrogen
emission spectrum you should be able to (a) determine the frequencies and the energies
associated with these wavelengths, (b) be able to use the Bohr equation to calculate the
wavelenths expected for the Balmer series of the hydrogen atom, (c) be able to quantitatively
compare results and Bohr's - Answer (a) c = (lambda)*v
(b) E = hv
(c) E = hv/(lambda)
E = Rh[(1/h)i^2 - (i/h)f^2]
Exp. 3 - Small-Scale Techniques - Answer
Explain the complementary nature of absorbed/observed colors. - Answer Depending on the
wavelength, colors are absorbed or observed. Low wavelengths absorb violet and high
wavelengths absorbed. Each wavelength observed color is opposite its absorbed.
What is the fundamental reason why a substance absorbs visible light? - Answer It depends
on the number of interactions between photons and the absorbing molecules.
Describe the technique of calorimetry. - Answer Uses solutions of known concentrations of a
light absorbing substance, in order to compare the light absorption of an unknown solution.
Concentration can be obtained when a color match is found.
What process removes the energy from excited food dye molecules in aqueous solution? -
Answer Solvent molecules bumping billions of times per second against the excited food
molecules.
Be able to use the dilution equation given in this experiment to solve dilution problems. -
Answer CiVi = CfVf
Be able to describe the observations of OTO with tap water and water passed through the Brita
filter. Explain. - Answer When tap water was reacted, the solution turned yellow due to high
chlorine ion concentration. The Brita water turned a slightly lighter shade of yellow due to the Cl
ions being removed because it stuck to the activated carbons which have tiny pores so there is a
high surface area to react.
Be able to calculate a standard deviation by hand for a given data set. - Answer sum([(xi-
x)^2/N-1]^1/2)
