AP Chemistry Molarity Questions and Advanced Problem Solving

📚 Quick Study Guide

• 🧪 Molarity (M) is defined as the number of moles of solute per liter of solution. Formula: $M = \frac{moles \, of \, solute}{liters \, of \, solution}$
• ⚖️ To calculate moles, use the formula: $moles = \frac{mass}{molar \, mass}$
• 🌡️ Remember to convert volumes to liters (1 L = 1000 mL).
• 💧 Dilution formula: $M_1V_1 = M_2V_2$, where M is molarity and V is volume.
• 💡 Always pay attention to units! Make sure they are consistent before plugging numbers into formulas.

Practice Quiz

1. A solution is prepared by dissolving 5.85 grams of NaCl in enough water to make 500 mL of solution. What is the molarity of the solution?
   1. 0.1 M
   2. 0.2 M
   3. 0.3 M
   4. 0.4 M
2. What volume of a 2.0 M stock solution of KCl is needed to prepare 100 mL of a 0.5 M solution?
   1. 10 mL
   2. 20 mL
   3. 25 mL
   4. 50 mL
3. If 25.0 mL of a 1.0 M solution of HCl is diluted to 500 mL, what is the new molarity?
   1. 0.05 M
   2. 0.10 M
   3. 0.125 M
   4. 0.25 M
4. How many grams of NaOH are needed to prepare 250 mL of a 0.1 M solution?
   1. 1.0 g
   2. 2.0 g
   3. 0.5 g
   4. 4.0 g
5. A solution contains 20.0 g of glucose (C6H12O6) in 200.0 mL of solution. What is the molarity of the solution?
   1. 0.11 M
   2. 0.56 M
   3. 0.05 M
   4. 1.55 M
6. What is the molarity of a solution containing 4.0 g of sodium hydroxide (NaOH) in 500.0 mL of solution?
   1. 0.20 M
   2. 0.30 M
   3. 0.40 M
   4. 0.50 M
7. If you mix 100.0 mL of a 0.5 M NaCl solution with 200.0 mL of water, what is the final concentration of the NaCl solution?
   1. 0.167 M
   2. 0.25 M
   3. 0.33 M
   4. 0.40 M