0.100103
mol/L
0.100103
mol
100.1027
mM
0.100103
mol/L
0.100103
mol
100.1027
mM
The Molarity Calculator determines the molar concentration of a solution from the mass of solute, its molecular weight, and the volume of the solution. Molarity (M) is defined as the number of moles of solute per liter of solution and is the most widely used unit of concentration in chemistry and biology.
Enter the mass of your solute in grams, the molecular weight in g/mol, and the solution volume in milliliters to calculate the molarity. This tool is indispensable for preparing standard solutions, calculating reagent amounts, and converting between mass and molar quantities in the laboratory.
Molarity is calculated in two steps:
Step 1: Calculate moles
moles = mass (g) / molecular weight (g/mol)
Step 2: Calculate molarity
M = moles / volume (L)
For example, dissolving 5.85 g of NaCl (MW = 58.44 g/mol) in 1000 mL gives 0.1 moles in 1 L, yielding 0.1 M NaCl. The millimolar (mM) value is simply molarity multiplied by 1000.
Inputs
Results
Dissolving 5.85 g NaCl in 1 L of solution gives approximately 0.1 M sodium chloride, a common physiological saline starting point.
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Results
Dissolving 18.02 g of glucose (MW 180.16) in 500 mL yields a 0.2 M (200 mM) stock solution.
Molarity (M) is defined as the number of moles of solute per liter of solution. It is the most common way to express the concentration of a solution in chemistry. A 1 M solution contains exactly one mole of solute dissolved in enough solvent to make one liter of total solution. Molarity depends on temperature because solution volume changes with temperature.
The molecular weight (molar mass) is the sum of the atomic weights of all atoms in the molecule. It can be found on the reagent bottle label, in chemical databases like PubChem, or calculated from the molecular formula using a periodic table. For example, NaCl has MW = 22.99 (Na) + 35.45 (Cl) = 58.44 g/mol.
Molarity (M) is moles of solute per liter of solution, while molality (m) is moles of solute per kilogram of solvent. Molarity depends on temperature because volume changes, while molality does not. Molality is preferred in colligative property calculations (boiling point elevation, freezing point depression) because it is temperature-independent.
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