Which quantity does concentration specifically refer to in a solution?

Concentration specifically refers to the amount of solute present in a given volume of solution. It quantifies how much of a substance (the solute) is dissolved in a certain volume of solvent or solution, providing insight into the strength or dilution of that solution. This measurement is crucial in chemistry because it affects reaction rates, the properties of solutions, and the behavior of solutes in various applications.

Different methods can be used to express concentration, such as molarity (moles of solute per liter of solution), mass percent, or molality (moles of solute per kilogram of solvent). This focus on the solute amount allows chemists to predict and manipulate chemical reactions and processes effectively.