Question

A solution is prepared by dissolving 1.928 g of KNO₃ into enough water to make 651 ml. What is the molarity of the solution?

Answer 1

The molarity of a KNO₃ solution made by dissolving 1.928 g in 651 ml of water is 0.0293 M. This is calculated by dividing the number of moles of KNO₃ by the volume in liters.

Step-by-step explanation:

The student has asked about calculating the molarity of a solution that results from dissolving 1.928 grams of KNO₃ in 651 mL of water. The molarity of a solution is defined as the number of moles of solute per liter of solution (mol/L). To find the molarity, we follow these steps:

1. First, we calculate the moles of KNO₃ by using its molar mass. KNO₃ has a molar mass of approximately 101.1 g/mol (39.1 g/mol for K + 14.0 g/mol for N + 3 × 16.0 g/mol for O).
2. We divide the mass of KNO₃ by its molar mass to determine the number of moles. Moles = 1.928 g / 101.1 g/mol = 0.01907 mol.
3. Since we want our solution volume in liters for molarity, convert the volume of the solution from milliliters to liters. Volume = 651 mL × (1 L / 1000 mL) = 0.651 L.
4. Finally, the molarity is calculated by dividing the moles of KNO₃ by the volume of the solution in liters. Molarity = 0.01907 mol / 0.651 L = 0.0293 M.

Therefore, the molarity of the KNO₃ solution is 0.0293 M.