AP Chemistry Questions on Dalton's Law: Exam Prep

📚 Quick Study Guide

• ⚛️ Dalton's Law of Partial Pressures states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases.
• ⚗️ Mathematically, Dalton's Law is expressed as: $P_{total} = P_1 + P_2 + P_3 + ... + P_n$, where $P_{total}$ is the total pressure and $P_1, P_2, ..., P_n$ are the partial pressures of the individual gases.
• 🌡️ The partial pressure of a gas is the pressure that the gas would exert if it occupied the same volume alone.
• 📐 The partial pressure of a gas can be calculated using the ideal gas law: $P_i = \frac{n_iRT}{V}$, where $P_i$ is the partial pressure of gas $i$, $n_i$ is the number of moles of gas $i$, $R$ is the ideal gas constant, $T$ is the temperature in Kelvin, and $V$ is the volume.
• 💡 Mole fraction ($X_i$) is the ratio of the number of moles of a particular gas to the total number of moles of all gases in the mixture: $X_i = \frac{n_i}{n_{total}}$.
• 📝 The partial pressure of a gas can also be calculated using the mole fraction: $P_i = X_i \cdot P_{total}$.

🧪 Practice Quiz

1. What does Dalton's Law of Partial Pressures state?
   1. A) The total pressure of a gas mixture is the product of the partial pressures.
   2. B) The total pressure of a gas mixture is the sum of the partial pressures.
   3. C) The total pressure of a gas mixture is the average of the partial pressures.
   4. D) The total pressure of a gas mixture is the difference between the highest and lowest partial pressures.
2. A container holds 2 moles of nitrogen gas and 3 moles of oxygen gas. If the total pressure is 10 atm, what is the partial pressure of nitrogen?
   1. A) 4 atm
   2. B) 5 atm
   3. C) 6 atm
   4. D) 10 atm
3. Which of the following formulas is used to calculate the partial pressure of a gas using its mole fraction?
   1. A) $P_i = X_i + P_{total}$
   2. B) $P_i = \frac{X_i}{P_{total}}$
   3. C) $P_i = X_i \cdot P_{total}$
   4. D) $P_i = \frac{P_{total}}{X_i}$
4. A flask contains 1 mole of helium, 2 moles of neon, and 3 moles of argon. The total pressure is 12 atm. What is the partial pressure of neon?
   1. A) 2 atm
   2. B) 4 atm
   3. C) 6 atm
   4. D) 8 atm
5. If the partial pressure of oxygen in a gas mixture is 200 mmHg and the total pressure is 760 mmHg, what is the mole fraction of oxygen?
   1. A) 0.263
   2. B) 0.395
   3. C) 0.605
   4. D) 0.737
6. A gas mixture contains nitrogen, oxygen, and carbon dioxide. The partial pressures are 40 kPa, 20 kPa, and 10 kPa, respectively. What is the total pressure?
   1. A) 50 kPa
   2. B) 60 kPa
   3. C) 70 kPa
   4. D) 80 kPa
7. What is the effect on the partial pressure of a gas if the number of moles of that gas is doubled, while the total pressure and volume remain constant?
   1. A) The partial pressure is halved.
   2. B) The partial pressure remains the same.
   3. C) The partial pressure is doubled.
   4. D) The partial pressure is quadrupled.