Molarity Calculator

Molarity (M) is the concentration of a solute expressed as moles of solute per liter of solution (mol/L). Molality (m) is the concentration expressed as moles of solute per kilogram of solvent (mol/kg). Molarity can change slightly with temperature because liquids expand or contract, whereas molality is temperature-independent because mass does not change.

To calculate the molar mass of a compound, sum the standard atomic weights of all its constituent atoms. For example, for water (H₂O), multiply the atomic weight of Hydrogen (1.008) by 2, and add the atomic weight of Oxygen (15.999), yielding approximately 18.015 g/mol.

First, calculate the required mass of solute using: Mass = Molarity × Volume (in Liters) × Molar Mass. Weigh out this exact mass of solute, dissolve it in a small amount of solvent (such as distilled water) inside a volumetric flask, and then add solvent until the solution volume reaches the calibration mark exactly.

A standard solution is any solution whose concentration is precisely known. These solutions are prepared by dissolving a highly pure primary standard chemical (like sodium carbonate or potassium hydrogen phthalate) in an exact volume of solvent.

Parts per million (ppm) is equivalent to milligrams of solute per liter of solution (mg/L). To convert molarity (mol/L) to ppm, multiply the molarity by the molar mass (g/mol) of the solute, and then multiply by 1,000 (e.g., ppm = M × Molar Mass × 1,000).