AP Chemistry Graham's Law Questions and Answer Explanations

📚 Quick Study Guide

• 💨 Graham's Law Definition: Graham's Law states that the rate of diffusion or effusion of a gas is inversely proportional to the square root of its molar mass.
• ➗ Formula: $\frac{Rate_1}{Rate_2} = \sqrt{\frac{M_2}{M_1}}$, where $Rate_1$ and $Rate_2$ are the rates of effusion or diffusion for gas 1 and gas 2, respectively, and $M_1$ and $M_2$ are their respective molar masses.
• ⚖️ Molar Mass: Remember to calculate molar mass correctly using the periodic table. Units are typically in g/mol.
• 🌡️ Temperature: Graham's Law assumes constant temperature and pressure.
• 🔑 Effusion vs. Diffusion: Effusion is the process where a gas escapes through a tiny hole, while diffusion is the spread of a gas throughout a space. Graham's Law applies to both.

🧪 Practice Quiz

1. Question 1: Which gas effuses faster: Hydrogen (H₂) or Oxygen (O₂)?
   1. Hydrogen (H₂)
   2. Oxygen (O₂)
   3. They effuse at the same rate
   4. Cannot be determined
2. Question 2: What is the ratio of the rate of effusion of Helium (He) to that of Nitrogen (N₂)?
   1. $\sqrt{\frac{7}{2}}$
   2. $\sqrt{\frac{2}{7}}$
   3. $\frac{7}{2}$
   4. $\frac{2}{7}$
3. Question 3: A gas effuses at a rate that is twice as fast as $SO_2$. What is the molar mass of the gas?
   1. 16 g/mol
   2. 32 g/mol
   3. 64 g/mol
   4. 128 g/mol
4. Question 4: If gas A has a molar mass of 25 g/mol and gas B has a molar mass of 100 g/mol, how much faster does gas A effuse compared to gas B?
   1. 2 times faster
   2. 4 times faster
   3. $\sqrt{2}$ times faster
   4. $\sqrt{4}$ times faster
5. Question 5: Which of the following factors does NOT affect the rate of effusion?
   1. Molar mass
   2. Temperature
   3. Pressure
   4. Volume
6. Question 6: Two gases, X and Y, have rates of effusion in the ratio of 1:3. If the molar mass of X is 9 g/mol, what is the molar mass of Y?
   1. 1 g/mol
   2. 3 g/mol
   3. 27 g/mol
   4. 81 g/mol
7. Question 7: A container has equal moles of $H_2$ and $O_2$. If a small hole is opened, what is the ratio of $H_2$ to $O_2$ that initially escapes?
   1. 1:1
   2. 1:4
   3. 4:1
   4. 16:1