what is the molarity of a solution, if 12.0 g of KCl is dissolved into 500mL of H20

To find the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).

First, we need to calculate the number of moles of KCl. The molar mass of KCl is the sum of the atomic masses of potassium (K) and chlorine (Cl), which is 39.10 g/mol + 35.45 g/mol = 74.55 g/mol.

Using the given mass of KCl (12.0 g) and its molar mass (74.55 g/mol), we can calculate the number of moles as follows:

moles of KCl = mass of KCl / molar mass of KCl
moles of KCl = 12.0 g / 74.55 g/mol
moles of KCl ≈ 0.161 mol

Next, we need to convert the volume of the solution from milliliters to liters. Since 1 L is equal to 1000 mL, the volume of the solution is 500 mL / 1000 mL/L = 0.500 L.

Now we can calculate the molarity (M) of the solution using the formula:

Molarity (M) = moles of solute / volume of solution (in liters)

Molarity (M) = 0.161 mol / 0.500 L
Molarity (M) ≈ 0.322 M

Therefore, the molarity of the KCl solution is approximately 0.322 M.