Portage Learning CHEM
121 Final Exam Study
Guide – Updated
2025/2026 with Verified
Answers and In-Depth
Explanations
,I. Standard Physical Constants and Conversion
Factors
For calculation-intensive sections of the examination, students are advised to utilize the
following standard values and conversion factors, ensuring all intermediate calculations are
performed with appropriate precision before rounding the final answer based on significant
figure rules.
Table 1: Standard Physical Constants and Conversion Factors
Constant/Factor Value Unit
Gas Constant (R) 0.08206 L \cdot atm / (mol \cdot K)
Avogadro’s Number (N_A) 6.022 \times 10^{23} particles / mol
Standard Temperature and 0^\circ C and 1.00 atm N/A
Pressure (STP)
Standard Molar Volume at STP 22.4 L / mol
Conversion: 1 \text{ atm} 760 mmHg or torr
Conversion: 1 \text{ pound} 453.6 grams
Conversion: 1 \text{ L} 1.06 quarts \ (qt)
Conversion: 0^\circ C 273.15 K
Note: Atomic masses utilized in calculations are rounded to the nearest tenth of a gram per
mole (g/mol), unless otherwise specified.
II. CHEM 121 Comprehensive Final Examination
(Q1–Q65)
, A. Foundational Concepts and Atomic Structure
1. A laboratory measurement of 3.56 \text{ grams} is divided by 1.8 \times 10^{-2} \text{ mL}
and then added to 9.50 \text{ g/mL}. Report the final answer, ensuring correct application
of significant figure rules for combined operations.
2. A sample of gas is measured at 345 \text{ Kelvin}. What is this temperature in degrees
Celsius (\circ C) and degrees Fahrenheit (\circ F)?
3. The density of a newly synthesized liquid is 1.25 \text{ g/mL}. Calculate the volume, in
quarts, that a 250.0 \text{ g} sample of this liquid would occupy.
4. Determine the number of protons, neutrons, and electrons in the iron(II) ion,
\text{Fe}^{2+}, assuming the most common isotope of iron (\text{Fe}-56).
5. Write the ground state electron configuration for the element Chromium (\text{Cr}, Z=24).
Explain why this configuration deviates from the expected Aufbau principle order.
6. Which of the following sets of quantum numbers (n, l, m_l, m_s) describes a permissible
orbital designation? a) (3, 3, -2, +1/2) b) (2, 1, 0, -1/2) c) (4, 2, -3, +1/2) d) (1, 1, 0, -1/2)
7. An electron is excited to the n=4 energy level. Calculate the energy, in Joules, emitted
when this electron transitions back to the ground state (n=1) in a hydrogen atom.
(Rydberg constant R_H = 2.18 \times 10^{-18} J).
B. Periodic Trends and Chemical Bonding
1. Explain the variation in atomic radius observed when moving from left to right across
Period 3 (Na to Ar) and when moving down Group 1 (Li to Cs).
2. Predict which element in each pair has the higher first ionization energy and provide a
physical justification: a) Potassium (\text{K}) or Bromine (\text{Br}) b) Fluorine (\text{F}) or
Chlorine (\text{Cl})
3. Compare the relative size of a neutral sodium atom (\text{Na}) and its corresponding ion
(\text{Na}^+). Provide a structural explanation for this size change.
4. Provide the systematic chemical name for the following compounds: a)
\text{Mg}(\text{OH})_2 b) \text{Fe}(\text{NO}_3)_3 c) \text{P}_2\text{O}_5
5. Write the chemical formula for the following compounds: a) Aluminum carbonate b)
Hydrofluoric acid c) Ammonium sulfate
6. Draw the Lewis electron structure for the chlorate ion (\text{ClO}_3^-) and use VSEPR
theory to determine the electron geometry and the molecular geometry around the central
chlorine atom.
7. Determine the molecular geometry and predict the polarity (polar or nonpolar) of the sulfur
tetrafluoride molecule (\text{SF}_4).
8. What are the electron geometry and molecular geometry of Xenon Tetrafluoride
(\text{XeF}_4)?
9. Arrange the following substances in order of increasing boiling point and justify the
ranking based on the intermolecular forces (IMFs) present: propane
(\text{C}_3\text{H}_8), dimethyl ether (\text{CH}_3\text{OCH}_3), and water
(\text{H}_2\text{O}).
C. Quantitative Chemistry: Stoichiometry and Solutions
1. Calculate the molar mass of magnesium phosphate, \text{Mg}_3(\text{PO}_4)_2.
121 Final Exam Study
Guide – Updated
2025/2026 with Verified
Answers and In-Depth
Explanations
,I. Standard Physical Constants and Conversion
Factors
For calculation-intensive sections of the examination, students are advised to utilize the
following standard values and conversion factors, ensuring all intermediate calculations are
performed with appropriate precision before rounding the final answer based on significant
figure rules.
Table 1: Standard Physical Constants and Conversion Factors
Constant/Factor Value Unit
Gas Constant (R) 0.08206 L \cdot atm / (mol \cdot K)
Avogadro’s Number (N_A) 6.022 \times 10^{23} particles / mol
Standard Temperature and 0^\circ C and 1.00 atm N/A
Pressure (STP)
Standard Molar Volume at STP 22.4 L / mol
Conversion: 1 \text{ atm} 760 mmHg or torr
Conversion: 1 \text{ pound} 453.6 grams
Conversion: 1 \text{ L} 1.06 quarts \ (qt)
Conversion: 0^\circ C 273.15 K
Note: Atomic masses utilized in calculations are rounded to the nearest tenth of a gram per
mole (g/mol), unless otherwise specified.
II. CHEM 121 Comprehensive Final Examination
(Q1–Q65)
, A. Foundational Concepts and Atomic Structure
1. A laboratory measurement of 3.56 \text{ grams} is divided by 1.8 \times 10^{-2} \text{ mL}
and then added to 9.50 \text{ g/mL}. Report the final answer, ensuring correct application
of significant figure rules for combined operations.
2. A sample of gas is measured at 345 \text{ Kelvin}. What is this temperature in degrees
Celsius (\circ C) and degrees Fahrenheit (\circ F)?
3. The density of a newly synthesized liquid is 1.25 \text{ g/mL}. Calculate the volume, in
quarts, that a 250.0 \text{ g} sample of this liquid would occupy.
4. Determine the number of protons, neutrons, and electrons in the iron(II) ion,
\text{Fe}^{2+}, assuming the most common isotope of iron (\text{Fe}-56).
5. Write the ground state electron configuration for the element Chromium (\text{Cr}, Z=24).
Explain why this configuration deviates from the expected Aufbau principle order.
6. Which of the following sets of quantum numbers (n, l, m_l, m_s) describes a permissible
orbital designation? a) (3, 3, -2, +1/2) b) (2, 1, 0, -1/2) c) (4, 2, -3, +1/2) d) (1, 1, 0, -1/2)
7. An electron is excited to the n=4 energy level. Calculate the energy, in Joules, emitted
when this electron transitions back to the ground state (n=1) in a hydrogen atom.
(Rydberg constant R_H = 2.18 \times 10^{-18} J).
B. Periodic Trends and Chemical Bonding
1. Explain the variation in atomic radius observed when moving from left to right across
Period 3 (Na to Ar) and when moving down Group 1 (Li to Cs).
2. Predict which element in each pair has the higher first ionization energy and provide a
physical justification: a) Potassium (\text{K}) or Bromine (\text{Br}) b) Fluorine (\text{F}) or
Chlorine (\text{Cl})
3. Compare the relative size of a neutral sodium atom (\text{Na}) and its corresponding ion
(\text{Na}^+). Provide a structural explanation for this size change.
4. Provide the systematic chemical name for the following compounds: a)
\text{Mg}(\text{OH})_2 b) \text{Fe}(\text{NO}_3)_3 c) \text{P}_2\text{O}_5
5. Write the chemical formula for the following compounds: a) Aluminum carbonate b)
Hydrofluoric acid c) Ammonium sulfate
6. Draw the Lewis electron structure for the chlorate ion (\text{ClO}_3^-) and use VSEPR
theory to determine the electron geometry and the molecular geometry around the central
chlorine atom.
7. Determine the molecular geometry and predict the polarity (polar or nonpolar) of the sulfur
tetrafluoride molecule (\text{SF}_4).
8. What are the electron geometry and molecular geometry of Xenon Tetrafluoride
(\text{XeF}_4)?
9. Arrange the following substances in order of increasing boiling point and justify the
ranking based on the intermolecular forces (IMFs) present: propane
(\text{C}_3\text{H}_8), dimethyl ether (\text{CH}_3\text{OCH}_3), and water
(\text{H}_2\text{O}).
C. Quantitative Chemistry: Stoichiometry and Solutions
1. Calculate the molar mass of magnesium phosphate, \text{Mg}_3(\text{PO}_4)_2.
