How is the concentration of a solution expressed in mol/L determined?

The concentration of a solution expressed in mol/L (molarity) is determined by calculating the number of moles of solute and dividing that by the volume of the solution in liters. This relationship is defined by the formula:

[ \text{Concentration (mol/L)} = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}} ]

Using this formula, if you know how many moles of solute are present and the total volume of the solution, you can find the molarity. This is particularly useful in solving problems involving reactions in solution, as it provides a clear measure of how much solute is present in a specified volume of solvent.

In contrast, other choices do not accurately represent how concentration is calculated. For example, dividing by volume in cubic centimeters does not provide the correct units for molarity, and multiplying moles by volume does not inherently relate to concentration. Measuring by mass of solute over volume does not yield the measurement in moles and is hence inaccurate for expressing concentration in terms of molarity. Therefore, the formulation in option C accurately implements the definition of molarity.