How is molarity calculated?

Molarity is defined as the concentration of a solution expressed in terms of the amount of solute in moles per liter of solution. The correct formulation is that molarity (M) is calculated by taking the number of moles of the solute and dividing it by the volume of the solution in liters. This relationship shows how molarity quantifies how much solute is present in a specified amount of the entire solution, which is crucial for understanding the behavior of solutions in chemical reactions.

The use of moles rather than mass ensures that the measurement accounts for the number of particles or molecules in the solution, regardless of their individual mass. Therefore, this formulation is essential for accurate stoichiometric calculations in chemistry, where the number of reacting particles is pivotal.

Incorporating other components such as grams of solute or simply mass does not provide the necessary context for how much of that mass translates into moles, which is why those options do not accurately define molarity.