The number of moles of solute per liter of solution is known as what?

• A. Molality
• B. Molarity
• C. Normality
• D. Mole Fraction

Answer: (B)

Molarity is the measure of concentration that uses volume. It is defined as the number of moles of solute per liter of solution, written as mol/L (often shown with the symbol M). This tells you how much solute is present in a given amount of solution, which is why it’s a key way chemists express how concentrated a solution is.

Temperature can affect molarity because changing temperature can change the solution’s volume, so the same amount of solute in a larger or smaller liter of solution changes the molarity. This is different from molality, which is moles of solute per kilogram of solvent and does not depend on volume or temperature. Normality expresses equivalents per liter and varies with the reaction context, not just straightforward mole count. Mole fraction is the ratio of moles of solute to total moles in the solution and is dimensionless, not a concentration per liter. For example, dissolving 2 moles of solute in 1 liter of solution gives 2 M, but dissolving the same 2 moles in 2 liters would give 1 M.