Molaritas

Molaritas, or molarity (symbol M), is a standard measure of the concentration of a solute in a solution. It expresses the amount of solute, in moles, per liter of solution.

Definition and formula: M = n / V, where n is the number of moles of solute and V is the volume of solution in liters. Therefore, a 1 M solution contains 1 mole of solute per liter of solution.

Preparation and calculation: To prepare a solution of known molarity, weigh the desired amount of solute, dissolve it in a solvent, and dilute to the final volume in a volumetric flask. The moles can be found from mass and molar mass: n = mass / molar mass, so M = (mass / molar mass) / V. To convert molarity to mass concentration, multiply by the molar mass.

Temperature dependence and related measures: Molarity depends on volume, which changes with temperature; thus it is temperature dependent. Molality, defined as moles of solute per kilogram of solvent, is not temperature dependent. In precise work, activities and density corrections may be used to describe solution behavior more accurately than molarity alone.

Applications and typical values: Molarity is widely used in chemistry, biology, medicine, and environmental science for calculations in reactions, dilutions, and titrations. Working solutions commonly range from about 0.001 M to several M; concentrated acids and bases can reach around 18 M.

Limitations: For highly concentrated solutions, non-ideal behavior means that concentration alone does not fully describe the solution’s properties; more accurate descriptions use activity coefficients. Accurate preparation also requires careful control of temperature to ensure the desired final volume.