What is the molarity of a solution prepared by dissolving 15.0 grams of KNO_3 in 75.0 mL of solution? (Molar mass of KNO_3 = 101.1 g/mol)

• A. 0.198 M
• B. 1.98 M
• C. 2.00 M
• D. 0.150 M

Answer: (B)

Verified step by step guidance

1. Identify the given information: mass of KNO_3 = 15.0 g, volume of solution = 75.0 mL, and molar mass of KNO_3 = 101.1 g/mol.
2. Convert the volume from milliliters to liters because molarity is expressed in moles per liter: use the conversion \$1 \, \text{L} = 1000 \ \text{mL}\(, so \)V = \frac{75.0}{1000} \ \text{L}$.
3. Calculate the number of moles of KNO_3 using its molar mass with the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{15.0 \ \text{g}}{101.1 \ \text{g/mol}}\).
4. Use the definition of molarity, which is moles of solute divided by liters of solution: \(M = \frac{\text{moles of KNO}_3}{\text{volume in liters}}\).
5. Substitute the values from steps 2 and 3 into the molarity formula to find the molarity of the solution.