Answer:
a. The molar mass of potassium nitrate (KNO3) can be calculated by adding the atomic masses of potassium (K), nitrogen (N), and three oxygen atoms (O).
Molar mass of KNO3 = atomic mass of K + atomic mass of N + (3 x atomic mass of O)
= 39.10 g/mol + 14.01 g/mol + (3 x 16.00 g/mol)
= 101.10 g/mol
Therefore, the molar mass of potassium nitrate is 101.10 g/mol.
b. The number of moles of potassium nitrate can be calculated using the formula:
moles = mass / molar mass
mass of KNO3 = 75.0 g
molar mass of KNO3 = 101.10 g/mol
moles of KNO3 = 75.0 g / 101.10 g/mol
= 0.741 mol
Therefore, there are 0.741 moles of potassium nitrate in the solution.
c. Molarity (M) is defined as the number of moles of solute per liter of solution.
Volume of solution = 725 mL = 0.725 L
Molarity (M) = moles of solute / volume of solution in liters
Molarity (M) = 0.741 mol / 0.725 L
= 1.02 M
Therefore, the molarity of the potassium nitrate solution is 1.02 M.