What does Molarity measure?

Molarity is a quantitative measure of the concentration of a solute in a solution. Specifically, it quantifies the number of moles of a solute present in one liter of solvent. This is crucial in chemistry as it informs how much of a substance is dissolved in a given volume, allowing for precise calculations and reactions in various chemical processes.

In practice, knowing the molarity of a solution allows chemists to predict how substances will interact, determine how much of a reactant is needed for a reaction to occur, and ensure consistency in experimental procedures. This concept is foundational in fields like analytical chemistry, biochemistry, and environmental science, where the concentration of solutions significantly impacts results and outcomes.

Other options relate to different concepts that do not pertain to the measurement of concentration. For instance, gas concentration in the air, the mass of a solution, and temperature measurements serve different purposes and are not relevant to the definition of molarity.