Examples of Ideal Gas Law Calculations in Chemistry

📚 Quick Study Guide

• 🌡️ The Ideal Gas Law relates pressure (P), volume (V), number of moles (n), ideal gas constant (R), and temperature (T): $PV = nRT$.
• 🔢 R, the ideal gas constant, has different values depending on the units used for pressure and volume. Common values include $0.0821 \frac{L \cdot atm}{mol \cdot K}$ and $8.314 \frac{J}{mol \cdot K}$.
• 📝 Standard Temperature and Pressure (STP) is defined as 0°C (273.15 K) and 1 atm.
• 💡 Remember to always use consistent units! Convert temperature to Kelvin (K = °C + 273.15) and ensure pressure and volume units match your chosen R value.
• 🔑 Molar mass (M) can be used to relate mass (m) to moles (n): $n = \frac{m}{M}$.

🧪 Practice Quiz

1. What is the volume occupied by 2 moles of an ideal gas at STP?
   1. 11.2 L
   2. 22.4 L
   3. 44.8 L
   4. 33.6 L
2. If the pressure of a gas is doubled and the temperature is halved, what happens to the volume, assuming the number of moles remains constant?
   1. The volume doubles.
   2. The volume halves.
   3. The volume remains the same.
   4. The volume is quartered.
3. A container holds 4g of Helium gas at 27°C and 1 atm. What is the volume of the container? (Molar mass of He = 4 g/mol, R = 0.0821 L atm / (mol K))
   1. 2.46 L
   2. 24.6 L
   3. 12.3 L
   4. 4.92 L
4. Which of the following conditions would result in the highest pressure for a fixed amount of ideal gas?
   1. Low temperature, large volume
   2. High temperature, large volume
   3. Low temperature, small volume
   4. High temperature, small volume
5. What is the number of moles of an ideal gas occupying 10 L at 2 atm and 300 K? (R = 0.0821 L atm / (mol K))
   1. 0.81 moles
   2. 8.1 moles
   3. 0.081 moles
   4. 1.64 moles
6. If you have 5 grams of $N_2$ gas in a 5.0 L container at 25°C, what is the pressure in atm? (Molar mass of $N_2$ = 28 g/mol, R = 0.0821 L atm / (mol K))
   1. 0.21 atm
   2. 0.87 atm
   3. 1.06 atm
   4. 2.13 atm
7. Which of the following statements is NOT a condition of Ideal Gases?
   1. Elastic collisions between gas particles
   2. Gas particles have no volume
   3. There are attractive forces between gas particles
   4. Random motion of gas particles