Molarity calculator
Molarity is moles of solute per litre of solution. Enter what you have and the calculator fills in the rest.
- Moles of solute
- 1 mol
- Same concentration
- 1000 mmol/L
- Mass concentration
- 58.44 g/L
Show the working
- Mass of solute = 58.44
- Molar mass = 58.44
- Volume of solution = 1
- Moles of solute = 58.44 / 58.44 = 1
- Molarity = 1 / 1 = 1
- Same concentration = 1 * 1000 = 1000
- Mass concentration = 58.44 / 1 = 58.44
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- moles = mass / molar mass
- molarity M = moles / volume in litres
Molarity is per litre of *solution*, not per litre of solvent. Dissolving 58.44 g of salt in one litre of water gives slightly more than one litre of solution, and so slightly less than 1 M.
For work where temperature varies, molality (moles per kilogram of solvent) is the safer measure, because mass does not expand.
Frequently asked
What is 1 M?
One mole of solute per litre of solution. For sodium chloride at 58.44 g/mol that is 58.44 g made up to one litre.
How do I make 500 mL of 0.1 M solution?
Moles needed = 0.1 x 0.5 = 0.05 mol. Multiply by the molar mass to get the mass to weigh out, then make up to 500 mL.