Final answer:
The molarity of the potassium chloride solution is 0.391 M, calculated by dividing the number of moles of KCl (0.274 moles) by the volume of the solution in liters (0.700 L).
Step-by-step explanation:
The molarity of a solution can be calculated using the formula: M = moles of solute / liters of solution. To find the moles of potassium chloride (KCl), one must first find its molar mass. Potassium (K) has an atomic mass of approximately 39.1 g/mol, and chlorine (Cl) has an atomic mass of approximately 35.5 g/mol. Therefore, the molar mass of KCl is 39.1 g/mol + 35.5 g/mol = 74.6 g/mol.
Next, we convert the mass of KCl to moles:
- 20.45 g KCl ÷ 74.6 g/mol = 0.274 moles of KCl
Then, we convert the volume of the solution from mL to L:
- 700.0 mL × (1 L / 1000 mL) = 0.700 L
Now, we can calculate the molarity:
- M = 0.274 moles / 0.700 L = 0.391 M
Therefore, the molarity of the potassium chloride solution is 0.391 M.