Molarity Calculator

Calculate molarity, moles, volume, or mass for chemical solutions. Enter known values and select what to solve for.

Core Formula: Molarity (M) = moles of solute ÷ volume of solution (L) Related Formulas: Moles = Molarity × Volume (L) Volume (L) = Moles ÷ Molarity Moles = Mass (g) ÷ Molar Mass (g/mol) Mass (g) = Moles × Molar Mass (g/mol) Units: • Molarity: mol/L or M • Volume: L or mL (1 L = 1000 mL) • Molar Mass: g/mol (from periodic table)
Example 1 (Calculate Molarity): Dissolve 58.44 g NaCl (molar mass = 58.44 g/mol) in 1 L solution Moles = 58.44 g ÷ 58.44 g/mol = 1 mol Molarity = 1 mol ÷ 1 L = 1 M Example 2 (Calculate Mass Needed): Prepare 500 mL of 0.5 M NaOH (molar mass = 40.00 g/mol) Volume = 500 mL = 0.5 L Moles = 0.5 M × 0.5 L = 0.25 mol Mass = 0.25 mol × 40.00 g/mol = 10.0 g Example 3 (Calculate Volume): How much 2 M HCl contains 0.1 mol HCl? Volume = 0.1 mol ÷ 2 M = 0.05 L = 50 mL Example 4 (Glucose Solution): 100 mL of 0.1 M glucose (C₆H₁₂O₆, molar mass = 180.16 g/mol) Moles = 0.1 M × 0.1 L = 0.01 mol Mass = 0.01 mol × 180.16 g/mol = 1.80 g

What is molarity?

Molarity (M) is the number of moles of solute per liter of solution. It is one of the most common concentration units in chemistry. For example, 1 M NaCl means 1 mole of sodium chloride dissolved in 1 liter of solution.

How do I convert grams to moles?

Use the formula: moles = mass (g) ÷ molar mass (g/mol). For example, 58.44 g of NaCl ÷ 58.44 g/mol = 1 mole. The molar mass can be found on the periodic table by adding atomic masses.

What is the difference between molarity and molality?

Molarity (M) uses liters of solution as the denominator, while molality (m) uses kilograms of solvent. Molarity changes with temperature (volume expands), but molality does not.

How do I prepare a molar solution?

Calculate the mass needed using: mass = molarity × volume (L) × molar mass. Dissolve this mass in less solvent than needed, then add solvent to reach the final volume. For example, for 0.5 L of 1 M NaCl: 0.5 × 1 × 58.44 = 29.22 g NaCl in 0.5 L total solution.

Can I use milliliters instead of liters?

Yes, this calculator accepts both. Remember that 1 L = 1000 mL. The calculator automatically converts between units for your convenience.

What are common molarity values in the lab?

Common stock solutions: 1 M HCl, 6 M NaOH, 0.1 M buffer solutions. Biological systems often use millimolar (mM) or micromolar (μM) concentrations. For example, blood glucose is typically around 5 mM (0.005 M).

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