Chemistry Exam III Practice Problems

Practice Problems - Exam III

• Question 1: Which statement about gases is false? Gases are highly compressible, distances between molecules are large compared to distances within molecules, non-reacting gas mixtures are homogeneous, gases expand to fill the container. All gases are not colorless and odorless at room temperature. The false statement is about color and odorlessness.

• Question 2: How many different ml values are possible in the 3d sublevel? There are 5 possible ml values.

• Question 3: An electron cannot have which quantum numbers? An electron cannot have quantum numbers n=2, l=0, ml=0.

• Question 4: What volume of CO2 gas is produced from a reaction? Calculate the volume of CO2 (at 645 torr and 800 K) that's produced from 45g of CaCO3. The reaction is CaCO3(s) → CaO(s) + CO2(g). Use R = 0.08206 L·atm·K⁻¹·mol⁻¹.

• Question 5: What is the principle when filling degenerate orbitals? Electrons fill orbitals singly first (Hund's rule) with parallel spins.

• Question 6: Calculate the molar mass of an unknown gas. A flask with 3.16 L contains 9.33g of unknown gas at 32.0°C, and 1.00 atm. Calculate the molar mass (R = 0.08206 L atm K⁻¹ mol⁻¹).

• Question 7: Which is a valid statement of Charles' law?

• Question 8: Calculate the partial pressure of oxygen. Hydrogen and oxygen gases are mixed in a 7.75L flask at 65°C. The flask contains 0.482 g of H₂ and 4.98 g of O₂. What is the partial pressure of O₂? R = 0.08206 L atm K⁻¹ mol⁻¹; 1 atm = 760 mmHg.

• Question 9: Which quantum number describes the size and energy of an orbital? The principal quantum number (n) describes the size and energy of an orbital.

Additional Problems (Page 2)

• Question 11: How much CO2 is produced in a reaction? 6.00 kg of sodium bicarbonate reacts with excess hydrochloric acid at 37.0 °C and 1.00 atm. Calculate the product CO₂. Reaction is NaHCO₃ + HCl → NaCl + CO₂ + H₂O.

• Question 12: What is the density of NO₂? Find the density of NO₂ in a 4.50 L tank at 760.0 torr and 25.0 °C.

• Question 13: What is the pressure of a CH₄ gas sample? Calculate the pressure of a 6.022 g CH₄ gas sample in a 30.0 L vessel at 402 K.

• Question 14: Calculate the new pressure of a gas sample. A gas sample has a volume of 24.5 L at 1.57 atm. What is the pressure if the volume increases to 48.3 L?

• Question 15: Calculate the number of moles of gas. If 2.3 mol of a gas occupies 50.5mL, how many moles will occupy 85.5 mL at the same temperature and pressure?

• Question 16: Calculate the density of carbon dioxide gas. Calculate the density of carbon dioxide (CO₂) gas at 100°C and 17.0 atm. (R = 0.08206 L·atm·K⁻¹·mol⁻¹)

• Question 17: Calculate the number of N₂ molecules. How many N₂ molecules are present in a 2.5 L flask at 250°C and 650 mmHg? (R = 0.08206 L atm K⁻¹ mol⁻¹; 1 atm = 760 mmHg; 1 mole = 6.022 × 10²³ molecules)

• Question 18: Calculate the molar mass of Freon-11 gas. A sample of Freon-11 gas weighs 0.597 g and occupies 100 cm³ at 95°C and 1000 mmHg. Calculate the molar mass (R = 0.08206 L atm K⁻¹ mol⁻¹; 1 atm = 760 mmHg).

• Question 19: What does the shape of an atomic orbital describe? The shape of an atomic orbital describes the angular momentum quantum number (l) or the secondary quantum number.

Additional Problems (Pages 3, 4, 5, 6, 7, 8, 9 ,10, 11)

• Multiple-choice questions are included, focusing on topics like atomic structure, electron configurations, periodic trends, and chemical properties. Many of these require calculations and information from various parts of the periodic table.
• Be sure to review relevant sections of your textbook.