What term describes moles of solute per liter of solution?

• A. Molarity
• B. Molality
• C. Mass percent
• D. Normality

Answer: (A)

Molarity is the concentration described as moles of solute per liter of solution. It is calculated by dividing the number of moles of solute by the total volume of the solution in liters, giving units of moles per liter (M). This directly tells you how much solute is present in each liter of solution, which is why it’s the standard way labs express concentration for preparing solutions and doing stoichiometric calculations (for example, planning dilutions with C1V1 = C2V2). It’s different from molality, which uses kilograms of solvent rather than liters of solution; from mass percent, which is a mass-based ratio; and from normality, which measures equivalents per liter and depends on the reacting species. In practical lab work, molarity is the go-to measure when you need a straightforward amount of solute per fixed volume.