AP Chemistry Questions on Dilution Calculations

🧪 Quick Study Guide

• 🧮 Dilution involves reducing the concentration of a solution by adding more solvent.
• 📏 The key formula is: $M_1V_1 = M_2V_2$, where:
  • $M_1$ = Initial concentration (Molarity)
  • $V_1$ = Initial volume
  • $M_2$ = Final concentration (Molarity)
  • $V_2$ = Final volume
• ➕ Remember that $V_2$ is the *total* volume after dilution, so it includes the initial volume *plus* the volume of added solvent.
• 💡 Units for volume ($V_1$ and $V_2$) must be the same (e.g., both in mL or both in L).
• 🧐 Always double-check your units and make sure your answer makes sense in the context of the problem!

🧑‍🏫 Practice Quiz

1. Which of the following describes the process of dilution?
   1. Increasing the amount of solute in a solution.
   2. Decreasing the amount of solvent in a solution.
   3. Increasing the amount of solvent in a solution.
   4. Removing the solute from a solution.
2. What is the final concentration when 50.0 mL of a 2.0 M NaCl solution is diluted to 250.0 mL?
   1. 0.1 M
   2. 0.2 M
   3. 0.4 M
   4. 1.0 M
3. What volume of a 5.0 M stock solution is required to prepare 100.0 mL of a 0.25 M solution?
   1. 2.0 mL
   2. 5.0 mL
   3. 10.0 mL
   4. 20.0 mL
4. If 25.0 mL of water is added to 25.0 mL of a 1.0 M HCl solution, what is the approximate final concentration?
   1. 0.25 M
   2. 0.50 M
   3. 0.75 M
   4. 1.0 M
5. A student needs to prepare 500.0 mL of a 0.10 M solution from a 1.0 M stock solution. What volume of the stock solution is needed?
   1. 5.0 mL
   2. 25.0 mL
   3. 50.0 mL
   4. 100.0 mL
6. What is the molarity of a solution prepared by diluting 45.0 mL of 4.2 M KBr to 250.0 mL?
   1. 0.32 M
   2. 0.76 M
   3. 1.42 M
   4. 2.10 M
7. A solution is prepared by adding 50.0 mL of water to 50.0 mL of a 2.0 M solution. What is the final concentration?
   1. 1.0 M
   2. 1.5 M
   3. 2.0 M
   4. 2.5 M