Answer:
To calculate the molarity (M) of a solution, you need to know the moles of solute and the volume of the solution in liters.
First, let's calculate the moles of potassium nitrate (KNO3) using its molar mass. The molar mass of KNO3 is the sum of the atomic masses of potassium (K), nitrogen (N), and three oxygen (O) atoms:
Molar mass of KNO3 = (1 × atomic mass of K) + (1 × atomic mass of N) + (3 × atomic mass of O)
Using the atomic masses from the periodic table:
Atomic mass of K = 39.10 g/mol
Atomic mass of N = 14.01 g/mol
Atomic mass of O = 16.00 g/mol
Molar mass of KNO3 = (39.10 g/mol) + (14.01 g/mol) + (3 × 16.00 g/mol)
Molar mass of KNO3 ≈ 101.10 g/mol
Next, let's calculate the moles of KNO3:
Moles = mass / molar mass
Moles = 20.2 g / 101.10 g/mol
Moles ≈ 0.20 mol
Now, we have the moles of KNO3 and the volume of the solution in liters (250.0 ml = 0.250 L). Let's calculate the molarity:
Molarity = moles / volume (in liters)
Molarity = 0.20 mol / 0.250 L
Molarity = 0.80 M
Therefore, the molarity of the solution is approximately 0.80 M.
Step-by-step explanation: