What is the effect of dilution on the molarity of a solution?

When a solution is diluted, the concentration of the solute decreases because the same amount of solute is distributed in a larger volume of solvent. Molarity, defined as the number of moles of solute per liter of solution, is inversely related to volume. As the volume of the solution increases due to the addition of more solvent, the molarity must decrease because there are not more moles of solute present; they are simply dispersed in a larger volume.

In this process, even though the total amount of solute remains constant, the concentration (molarity) falls because the denominator in the molarity equation increases. Therefore, dilution leads to a decrease in molarity.