Answer:
the molarity of the solution is 0.25 M.
Step-by-step explanation:
To calculate the molarity of a solution, we need to know the amount of solute in moles and the volume of the solution in liters.
The first step is to calculate the amount of KOH in moles using its molar mass. The molar mass of KOH is the sum of the atomic weights of potassium (39.1 g/mol), oxygen (16.0 g/mol), and hydrogen (1.0 g/mol):
Molar mass of KOH = 39.1 g/mol + 16.0 g/mol + 1.0 g/mol = 56.1 g/mol
The amount of KOH in moles is:
moles of KOH = mass of KOH / molar mass of KOH
moles of KOH = 42.1 g / 56.1 g/mol
moles of KOH = 0.750 moles
Now that we know the amount of KOH in moles, we can calculate the molarity of the solution:
Molarity = moles of solute / liters of solution
Molarity = 0.750 moles / 3.0 L
Molarity = 0.25 M
Therefore, the molarity of the solution is 0.25 M.