Portage Learning CHEM
121
Final Exam Study Guide –
Updated 2025/2026 with
Verified Answers and
In-Depth Explanations
Portage Learning CHEM 121: Mock Final Examination
Instructions: This is a comprehensive, cumulative examination covering Modules 1-8. This
mock test is designed to be completed in 120 minutes. A scientific calculator and a Periodic
Table are required. For all calculation and short-answer questions, you must show all work and
logical steps to receive full credit, as partial credit may be awarded.
Examination Questions (1-65)
Module 1: Foundations of Chemistry
1. Express the number 0.000407 in scientific notation and state the number of significant
figures.
2. Perform the following calculation and report the answer to the correct number of
significant figures: (15.24 - 1.5) \times 3.00
3. A substance has a temperature of 315 K. What is its temperature in degrees Fahrenheit
(°F)?
4. A student in a virtual lab measures the mass of an empty beaker as 42.10 g. After adding
an unknown liquid, the total mass is 51.32 g. The volume of the liquid is measured as 12.5
mL. What is the density of the liquid in g/mL?
5. Classify each of the following as a pure element, a compound, a homogeneous mixture,
or a heterogeneous mixture: a) Air b) Iron (Fe) c) Carbon Dioxide (CO_2) d) Sand in water
Module 2: Atomic Structure and Periodic Properties
1. Determine the number of protons, neutrons, and electrons in a neutral atom of Cobalt-60
(^{60}Co).
2. Which of the following statements is TRUE? a) As wavelength increases, energy
increases. b) As frequency increases, energy decreases. c) As wavelength increases,
frequency decreases. d) An electron transition from n=1 to n=3 emits energy.
3. Which of the following sets of quantum numbers (n, l, m_l, m_s) is invalid (not allowed)?
a) (2, 1, 0, +1/2) b) (3, 0, 0, -1/2) c) (1, 1, 0, +1/2) d) (4, 2, -1, +1/2)
4. Write the complete (expanded) electron configuration for a neutral atom of Sulfur (S).
Portage Learning CHEM 121 Final Exam Study Guide – Updated 2025-2026 with Verified
Answers and In-Depth Explanations
, 5. Write the noble gas (shorthand) electron configuration for a neutral atom of Bromine (Br).
6. Which element has the largest atomic radius? a) Na b) Cl c) K d) Rb
7. Arrange the following elements in order of increasing first ionization energy: Li, O, F, Na.
Module 3: Chemical Bonding and Molecular Geometry
1. Which of the following is a characteristic property of ionic compounds? a) Low melting
points b) Poor conductors of electricity when molten c) Form distinct molecules d)
Completely dissociate in water to form electrolytes 2. Provide the correct chemical name
for Fe_2(SO_4)_3.
3. Provide the correct chemical name for N_2O_5.
4. Provide the correct chemical formula for Hydrosulfuric acid.
5. Draw the complete Lewis structure for carbon tetrachloride (CCl_4).
6. Draw the complete Lewis structure for the carbonate ion (CO_3^{2-}), including any
necessary resonance structures.
7. For the PCl_3 molecule: a) What is the total number of valence electrons? b) What is the
electron geometry? c) What is the molecular geometry (shape)?
8. For the SF_4 molecule: a) What is the electron geometry? b) What is the molecular
geometry (shape)?
9. Determine the molecular geometry of CO_2 and state whether the molecule is polar or
non-polar.
Module 4: Stoichiometry and Chemical Reactions
1. Calculate the molar mass of Ammonium Phosphate, (NH_4)_3PO_4.
2. What is the mass in grams of 0.450 moles of glucose (C_6H_{12}O_6)?
3. Calculate the percent composition by mass of carbon in caffeine (C_8H_{10}N_4O_2).
4. A compound is found to contain 40.0\% Carbon, 6.7\% Hydrogen, and 53.3\% Oxygen by
mass. What is the empirical formula of the compound?
5. Using the empirical formula from the previous question (CH_2O), if the molar mass of the
compound is determined to be 180.18 g/mol, what is its molecular formula?
6. Write the balanced chemical equation for the complete combustion of propane (C_3H_8).
7. Balance the following redox reaction in acidic solution: Cr_2O_7^{2-}(aq) + I^-(aq) \to
Cr^{3+}(aq) + I_2(s)
8. Assign oxidation states to each element in the following compound: K_2CrO_4.
9. Given the balanced reaction: 2 Al + 3 Cl_2 \to 2 AlCl_3 How many grams of AlCl_3 can be
produced from the reaction of 10.0 g of Al?
10. Consider the reaction: 2 N_2H_4(g) + N_2O_4(g) \to 3 N_2(g) + 4 H_2O(g) If 20.0 g of
N_2H_4 is mixed with 40.0 g of N_2O_4, what is the theoretical yield of N_2 in grams?
11. From the previous question, identify the limiting reactant and calculate the mass (in
grams) of the excess reactant that remains unreacted.
12. A solution is prepared by dissolving 14.2 g of sodium sulfate (Na_2SO_4) in enough water
to make 250.0 mL of solution. What is the molarity (M) of the solution?
Module 5: Gases
1. Which of the following is NOT a postulate of the Kinetic Molecular Theory of Gases? a)
Gas particles move randomly, in straight lines. b) The volume of the gas particles
themselves is negligible. c) Gas particles have strong intermolecular attractive forces. d)
The average kinetic energy is proportional to the temperature in Kelvin.
2. A 2.50 L sample of gas is at 105 kPa and 25^\circC. What will its volume be if the
pressure is changed to 90.0 kPa and the temperature is changed to 0^\circC?
Portage Learning CHEM 121 Final Exam Study Guide – Updated 2025-2026 with Verified
Answers and In-Depth Explanations
, 3. What volume (in L) will 0.750 moles of oxygen gas (O_2) occupy at a pressure of 2.00
atm and a temperature of 300 K? (R = 0.08206 L·atm/mol·K)
4. A 0.825 g sample of an unknown gas occupies 0.450 L at 1.00 atm and 298 K. What is
the molar mass of the gas?
5. What volume of H_2 gas, measured at STP (Standard Temperature and Pressure), is
produced when 5.00 g of Zinc (Zn) reacts with excess HCl? Zn(s) + 2 HCl(aq) \to
ZnCl_2(aq) + H_2(g)
6. A container holds a mixture of three gases: N_2 (0.5 atm), O_2 (0.3 atm), and Ar (0.7
atm). What is the total pressure inside the container?
7. A 10.0 L flask contains 2.0 moles of N_2 and 3.0 moles of H_2 at 25^\circC. What is the
mole fraction of N_2?
Module 6: Kinetics and Equilibrium
1. Which of the following will increase the rate of a chemical reaction? a) Decreasing the
temperature. b) Adding a catalyst. c) Decreasing the concentration of reactants. d)
Removing an inhibitor. e) Both b) and d).
2. For the reaction A + B \to C, the following initial rate data was collected:
Experiment Initial [A] (M) Initial (M) Initial Rate (M/s)
1 0.10 0.10 1.2 \times 10^{-3}
2 0.20 0.10 4.8 \times 10^{-3}
3 0.10 0.20 2.4 \times 10^{-3}
Determine the rate law for this reaction. 43. Using the data from the previous question, calculate
the value and units of the rate constant, k. 44. The half-life of a first-order reaction: a) Is the time
required for the concentration of a reactant to fall to half its initial value. b) Is constant at any
given temperature. c) Does not depend on the initial concentration. d) All of the above. 45. Write
the equilibrium constant expression (K_{eq}) for the following reaction: 4 NH_3(g) + 5 O_2(g) \
rightleftharpoons 4 NO(g) + 6 H_2O(g) 46. Consider the equilibrium: N_2(g) + 3 H_2(g) \
rightleftharpoons 2 NH_3(g) According to Le Chatelier's Principle, which way will the equilibrium
shift if NH_3 is removed from the system? 47. For the same equilibrium (N_2(g) + 3 H_2(g) \
rightleftharpoons 2 NH_3(g)), which way will the equilibrium shift if the volume of the container
is decreased (pressure is increased)? 48. For the equilibrium 2 SO_2(g) + O_2(g)
\rightleftharpoons 2 SO_3(g), the reaction is exothermic (\Delta H = -198 kJ). Which way will the
equilibrium shift if the temperature is increased?
Module 7: Acids, Bases, and Equilibrium
1. In the following reaction, identify the Brønsted-Lowry acid, base, conjugate acid, and
conjugate base: H_2PO_4^-(aq) + H_2O(l) \rightleftharpoons HPO_4^{2-}(aq) + H_3O^+
(aq)
2. Which of the following is true for a 0.10 M solution of a weak acid, HA? a) pH = 1.00 b)
[H_3O^+] = [HA] c) The pH is greater than 1.00 d) HA dissociates completely in water.
3. Calculate the pH of a solution with a hydronium ion concentration, [H_3O^+], of 3.5 \times
10^{-4} M.
4. What is the [H_3O^+] concentration of a solution with a pH of 2.50?
5. What is the pH of a 0.025 M Ba(OH)_2 solution? (Barium hydroxide is a strong base).
6. In a titration, 25.00 mL of HCl is neutralized by 18.50 mL of a 0.150 M NaOH solution.
What is the molarity of the HCl solution?
Portage Learning CHEM 121 Final Exam Study Guide – Updated 2025-2026 with Verified
Answers and In-Depth Explanations
121
Final Exam Study Guide –
Updated 2025/2026 with
Verified Answers and
In-Depth Explanations
Portage Learning CHEM 121: Mock Final Examination
Instructions: This is a comprehensive, cumulative examination covering Modules 1-8. This
mock test is designed to be completed in 120 minutes. A scientific calculator and a Periodic
Table are required. For all calculation and short-answer questions, you must show all work and
logical steps to receive full credit, as partial credit may be awarded.
Examination Questions (1-65)
Module 1: Foundations of Chemistry
1. Express the number 0.000407 in scientific notation and state the number of significant
figures.
2. Perform the following calculation and report the answer to the correct number of
significant figures: (15.24 - 1.5) \times 3.00
3. A substance has a temperature of 315 K. What is its temperature in degrees Fahrenheit
(°F)?
4. A student in a virtual lab measures the mass of an empty beaker as 42.10 g. After adding
an unknown liquid, the total mass is 51.32 g. The volume of the liquid is measured as 12.5
mL. What is the density of the liquid in g/mL?
5. Classify each of the following as a pure element, a compound, a homogeneous mixture,
or a heterogeneous mixture: a) Air b) Iron (Fe) c) Carbon Dioxide (CO_2) d) Sand in water
Module 2: Atomic Structure and Periodic Properties
1. Determine the number of protons, neutrons, and electrons in a neutral atom of Cobalt-60
(^{60}Co).
2. Which of the following statements is TRUE? a) As wavelength increases, energy
increases. b) As frequency increases, energy decreases. c) As wavelength increases,
frequency decreases. d) An electron transition from n=1 to n=3 emits energy.
3. Which of the following sets of quantum numbers (n, l, m_l, m_s) is invalid (not allowed)?
a) (2, 1, 0, +1/2) b) (3, 0, 0, -1/2) c) (1, 1, 0, +1/2) d) (4, 2, -1, +1/2)
4. Write the complete (expanded) electron configuration for a neutral atom of Sulfur (S).
Portage Learning CHEM 121 Final Exam Study Guide – Updated 2025-2026 with Verified
Answers and In-Depth Explanations
, 5. Write the noble gas (shorthand) electron configuration for a neutral atom of Bromine (Br).
6. Which element has the largest atomic radius? a) Na b) Cl c) K d) Rb
7. Arrange the following elements in order of increasing first ionization energy: Li, O, F, Na.
Module 3: Chemical Bonding and Molecular Geometry
1. Which of the following is a characteristic property of ionic compounds? a) Low melting
points b) Poor conductors of electricity when molten c) Form distinct molecules d)
Completely dissociate in water to form electrolytes 2. Provide the correct chemical name
for Fe_2(SO_4)_3.
3. Provide the correct chemical name for N_2O_5.
4. Provide the correct chemical formula for Hydrosulfuric acid.
5. Draw the complete Lewis structure for carbon tetrachloride (CCl_4).
6. Draw the complete Lewis structure for the carbonate ion (CO_3^{2-}), including any
necessary resonance structures.
7. For the PCl_3 molecule: a) What is the total number of valence electrons? b) What is the
electron geometry? c) What is the molecular geometry (shape)?
8. For the SF_4 molecule: a) What is the electron geometry? b) What is the molecular
geometry (shape)?
9. Determine the molecular geometry of CO_2 and state whether the molecule is polar or
non-polar.
Module 4: Stoichiometry and Chemical Reactions
1. Calculate the molar mass of Ammonium Phosphate, (NH_4)_3PO_4.
2. What is the mass in grams of 0.450 moles of glucose (C_6H_{12}O_6)?
3. Calculate the percent composition by mass of carbon in caffeine (C_8H_{10}N_4O_2).
4. A compound is found to contain 40.0\% Carbon, 6.7\% Hydrogen, and 53.3\% Oxygen by
mass. What is the empirical formula of the compound?
5. Using the empirical formula from the previous question (CH_2O), if the molar mass of the
compound is determined to be 180.18 g/mol, what is its molecular formula?
6. Write the balanced chemical equation for the complete combustion of propane (C_3H_8).
7. Balance the following redox reaction in acidic solution: Cr_2O_7^{2-}(aq) + I^-(aq) \to
Cr^{3+}(aq) + I_2(s)
8. Assign oxidation states to each element in the following compound: K_2CrO_4.
9. Given the balanced reaction: 2 Al + 3 Cl_2 \to 2 AlCl_3 How many grams of AlCl_3 can be
produced from the reaction of 10.0 g of Al?
10. Consider the reaction: 2 N_2H_4(g) + N_2O_4(g) \to 3 N_2(g) + 4 H_2O(g) If 20.0 g of
N_2H_4 is mixed with 40.0 g of N_2O_4, what is the theoretical yield of N_2 in grams?
11. From the previous question, identify the limiting reactant and calculate the mass (in
grams) of the excess reactant that remains unreacted.
12. A solution is prepared by dissolving 14.2 g of sodium sulfate (Na_2SO_4) in enough water
to make 250.0 mL of solution. What is the molarity (M) of the solution?
Module 5: Gases
1. Which of the following is NOT a postulate of the Kinetic Molecular Theory of Gases? a)
Gas particles move randomly, in straight lines. b) The volume of the gas particles
themselves is negligible. c) Gas particles have strong intermolecular attractive forces. d)
The average kinetic energy is proportional to the temperature in Kelvin.
2. A 2.50 L sample of gas is at 105 kPa and 25^\circC. What will its volume be if the
pressure is changed to 90.0 kPa and the temperature is changed to 0^\circC?
Portage Learning CHEM 121 Final Exam Study Guide – Updated 2025-2026 with Verified
Answers and In-Depth Explanations
, 3. What volume (in L) will 0.750 moles of oxygen gas (O_2) occupy at a pressure of 2.00
atm and a temperature of 300 K? (R = 0.08206 L·atm/mol·K)
4. A 0.825 g sample of an unknown gas occupies 0.450 L at 1.00 atm and 298 K. What is
the molar mass of the gas?
5. What volume of H_2 gas, measured at STP (Standard Temperature and Pressure), is
produced when 5.00 g of Zinc (Zn) reacts with excess HCl? Zn(s) + 2 HCl(aq) \to
ZnCl_2(aq) + H_2(g)
6. A container holds a mixture of three gases: N_2 (0.5 atm), O_2 (0.3 atm), and Ar (0.7
atm). What is the total pressure inside the container?
7. A 10.0 L flask contains 2.0 moles of N_2 and 3.0 moles of H_2 at 25^\circC. What is the
mole fraction of N_2?
Module 6: Kinetics and Equilibrium
1. Which of the following will increase the rate of a chemical reaction? a) Decreasing the
temperature. b) Adding a catalyst. c) Decreasing the concentration of reactants. d)
Removing an inhibitor. e) Both b) and d).
2. For the reaction A + B \to C, the following initial rate data was collected:
Experiment Initial [A] (M) Initial (M) Initial Rate (M/s)
1 0.10 0.10 1.2 \times 10^{-3}
2 0.20 0.10 4.8 \times 10^{-3}
3 0.10 0.20 2.4 \times 10^{-3}
Determine the rate law for this reaction. 43. Using the data from the previous question, calculate
the value and units of the rate constant, k. 44. The half-life of a first-order reaction: a) Is the time
required for the concentration of a reactant to fall to half its initial value. b) Is constant at any
given temperature. c) Does not depend on the initial concentration. d) All of the above. 45. Write
the equilibrium constant expression (K_{eq}) for the following reaction: 4 NH_3(g) + 5 O_2(g) \
rightleftharpoons 4 NO(g) + 6 H_2O(g) 46. Consider the equilibrium: N_2(g) + 3 H_2(g) \
rightleftharpoons 2 NH_3(g) According to Le Chatelier's Principle, which way will the equilibrium
shift if NH_3 is removed from the system? 47. For the same equilibrium (N_2(g) + 3 H_2(g) \
rightleftharpoons 2 NH_3(g)), which way will the equilibrium shift if the volume of the container
is decreased (pressure is increased)? 48. For the equilibrium 2 SO_2(g) + O_2(g)
\rightleftharpoons 2 SO_3(g), the reaction is exothermic (\Delta H = -198 kJ). Which way will the
equilibrium shift if the temperature is increased?
Module 7: Acids, Bases, and Equilibrium
1. In the following reaction, identify the Brønsted-Lowry acid, base, conjugate acid, and
conjugate base: H_2PO_4^-(aq) + H_2O(l) \rightleftharpoons HPO_4^{2-}(aq) + H_3O^+
(aq)
2. Which of the following is true for a 0.10 M solution of a weak acid, HA? a) pH = 1.00 b)
[H_3O^+] = [HA] c) The pH is greater than 1.00 d) HA dissociates completely in water.
3. Calculate the pH of a solution with a hydronium ion concentration, [H_3O^+], of 3.5 \times
10^{-4} M.
4. What is the [H_3O^+] concentration of a solution with a pH of 2.50?
5. What is the pH of a 0.025 M Ba(OH)_2 solution? (Barium hydroxide is a strong base).
6. In a titration, 25.00 mL of HCl is neutralized by 18.50 mL of a 0.150 M NaOH solution.
What is the molarity of the HCl solution?
Portage Learning CHEM 121 Final Exam Study Guide – Updated 2025-2026 with Verified
Answers and In-Depth Explanations
