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What does this calculator estimate?
A molarity calculator converts moles of solute and solution volume into concentration. Enter the moles and volume in liters to get molarity, plus grams per liter when a molar mass is given.
- Molarity = moles ÷ liters
- 1 mole ≈ 6.022×10²³ particles
- g/L = molarity × molar mass
What molarity measures
Molarity is the standard concentration unit in chemistry: moles of solute per liter of solution. It's used to prepare solutions, run stoichiometric calculations, and report concentrations because it directly links volume to particle count.
Limitations to watch for
Molarity depends on volume, which changes with temperature as liquids expand — molality (per kg of solvent) is temperature-independent. The estimate assumes the solute fully dissolves and the volume is the final solution volume, not just the solvent.
How to use it in practice
Dissolve the solute, then add solvent up to the final mark — never add solute to the final volume directly. Use molar mass to convert between grams and moles. For lab work, prepare with volumetric glassware for accuracy.
['Enter the moles of solute.', 'Enter the final solution volume in liters.', 'Optionally enter the molar mass to see g/L.']
How this calculator works
Formula
Molarity (M) = moles of solute ÷ liters of solution. Concentration in g/L = molarity × molar mass. A mole is the amount of substance containing Avogadro's number (6.022×10²³) of particles.
Worked example
2.0 moles of solute dissolved to make 0.5 L of solution: M = 2.0 ÷ 0.5 = 4.00 M. With NaCl (molar mass 58.44 g/mol), that's 4.00 × 58.44 ≈ 233.76 g/L.
Assumptions to verify
- The solute dissolves completely and uniformly.
- Volume is the final solution volume in liters.
- Temperature effects on volume are ignored.
Frequently asked questions
What is molarity?
The concentration of a solution in moles of solute per liter of solution. A 1 M solution has one mole of solute per liter.
How do I calculate molarity?
Divide moles of solute by liters of solution: M = moles ÷ liters. 2.0 mol in 0.5 L gives 4.00 M.
What is a mole?
A fixed count of particles (6.022×10²³, Avogadro's number). Moles let chemists count atoms and molecules by weighing them.
What is molar mass?
The mass of one mole of a substance in grams. For NaCl it's 58.44 g/mol; concentration in g/L = molarity × molar mass.
Is molarity affected by temperature?
Yes — liquids expand when heated, so the same solute in the same volume is less concentrated in molarity terms. For temperature-independent work, use molality.
What's the difference between molarity and molality?
Molarity is moles per liter of solution; molality is moles per kilogram of solvent. Molality doesn't change with temperature.
How do I make a molar solution?
Weigh the needed moles × molar mass, dissolve in less than the final volume, then add solvent to the final mark.
Cite this tool
BoringToolsKit. “Molarity Calculator.” boringtoolskit.com/molarity-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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