Molarity Calculator - Mass, Concentration & Dilution (M1V1=M2V2)
Free online chemistry molarity calculator and solution preparation assistant. Calculate solute mass required to prepare specific molar concentrations (M = mol/L), compute solution volume, and calculate stock solution dilutions using the standard M₁V₁ = M₂V₂ equation with common chemical reagent presets.
Molarity Calculator & Solution Solver
Calculate molar concentration, mass, volume, dilutions (C₁V₁=C₂V₂), titrations & PPM conversions with step-by-step proofs.
1. Select Unknown Variable to Calculate
Calculation Results
Complete Guide to Molarity & Solution Chemistry
Molarity (M), also known as molar concentration, is the fundamental SI-derived metric used by chemists, biologists, and laboratory researchers to quantify the concentration of a solute in a chemical solution. It represents the number of moles of solute dissolved per liter of total solution:
Molarity (M) vs. Molality (m): What is the Difference?
| Feature | Molarity (M) | Molality (m) | Normality (N) |
|---|---|---|---|
| Definition | Moles of solute per Liter of solution | Moles of solute per Kilogram of solvent | Gram equivalents per Liter of solution |
| SI Unit | mol/L or M | mol/kg or m | eq/L or N |
| Temperature Dependent? | Yes (liquid expands with heat) | No (mass is conserved) | Yes |
| Primary Use Case | Everyday lab bench preparation & volumetric assays | Thermodynamics, boiling point elevation, freezing depression | Acid-base & redox titration stoichiometry |
Core Solution Chemistry Formulas
When diluting a stock solution with solvent, total solute moles remain constant. The volume of stock solution required is V₁ = (C₂ × V₂) ÷ C₁.
To convert mass density (g/L or mg/mL) to molarity, divide concentration (g/L) by the solute's molecular weight (g/mol): M = C (g/L) ÷ MW.
For dilute aqueous solutions with density ρ ≈ 1.0 g/mL: Molarity (M) = PPM ÷ (Molar Mass × 1000).
A 1% (w/v) solution contains 10 g of solute per Liter. Therefore, Molarity = [%(w/v) × 10] ÷ Molar Mass.
Frequently Asked Questions (FAQ)
How do you calculate molarity from grams and milliliters?
Convert grams to moles by dividing by the molecular weight (g/mol). Then convert milliliters to liters by dividing by 1000. Finally, divide the moles by the volume in liters (M = moles / L).
What is the molarity of pure water?
Pure water has a molarity of 55.5 M. One liter of water weighs approximately 1000 grams. Dividing 1000 g by the molar mass of H₂O (18.015 g/mol) yields 55.51 mol/L.
What is the difference between 1 Molar and 1 Normal solution?
A 1 Molar (1 M) solution contains 1 mole of solute per liter. A 1 Normal (1 N) solution contains 1 equivalent of reactive species (H+, OH-, or electrons) per liter. For monoprotic acids like HCl, 1 M = 1 N. For diprotic acids like H₂SO₄, 1 M = 2 N.
Why should you add acid to water instead of water to acid?
Dissolving concentrated acids in water is intensely exothermic. Adding water to concentrated acid can cause rapid boiling and acid splatter. Always add acid slowly to a large volume of water with continuous stirring ('Do as you oughta, add acid to water').
Molarity & Chemical Solution Preparation Guide: Solute Mass, Concentration & Dilution (M1V1=M2V2)
Molarity (M) is the standard unit of concentration in chemical laboratories, denoting moles of solute dissolved per liter of solution. This guide covers solute mass calculations, molar mass stoichiometry, and stock solution dilution protocols.
Stoichiometric Solution Preparation Formulas
Molarity Formula: M = Moles / Volume (L) = Mass (g) / [Molecular Weight (g/mol) × Volume (L)]
Required Solute Mass (g) = Molarity (mol/L) × Molecular Weight (g/mol) × Volume (L)
Stock Dilution Equation: M₁ · V₁ = M₂ · V₂ (Initial Molarity × Initial Volume = Final Molarity × Final Volume)
Step-by-Step Instructions
Select Calculation Mode
Choose to solve for Molarity (M), Solute Mass (grams), Molecular Weight (g/mol), or Solution Volume (liters/mL).
Enter Chemical Parameters
Input solute mass in grams/milligrams, compound molar mass (MW in g/mol), and target final solution volume.
Compute Concentration & Dilution
The calculator applies standard stoichiometry equations (`M = moles / Volume = (mass / MW) / V`) with step-by-step mathematical working.
Access Stock Solution Dilution (C1V1 = C2V2)
Calculate precise aliquot volumes required to prepare serial dilutions from concentrated laboratory stock solutions.
Key Features & Capabilities
- Core stoichiometry engine: solves `Molarity (M) = Mass (g) / (Molar Mass (g/mol) * Volume (L))` for any variable
- Stock solution dilution calculator implementing the standard `C1 * V1 = C2 * V2` formula
- Extensive unit converter: grams (`g`), milligrams (`mg`), moles (`mol`), millimoles (`mmol`), liters (`L`), and milliliters (`mL`)
- Pre-loaded molar mass reference database for common laboratory reagents (NaCl, NaOH, HCl, Tris, EDTA, PBS)
- Mass concentration converter mapping between Molarity (`mol/L`), Millimolarity (`mM`), and `mg/mL`
- Instant laboratory-grade precision with step-by-step dimensional analysis output
Frequently Asked Questions
What is Molarity (M) and what is its standard formula?
Molarity (M), or molar concentration, is the number of moles of solute dissolved per liter of solution. The formula is: `Molarity (M) = n / V = (Mass in grams / Molar Mass in g/mol) / Volume in Liters`. A 1 M solution contains 1 mole of solute dissolved in a final volume of 1 liter of solution.
How do you calculate how to prepare a specific molar solution (e.g. 0.5 M NaCl in 500 mL)?
1. Identify molar mass: NaCl = 58.44 g/mol. 2. Convert volume to liters: 500 mL = 0.5 L. 3. Calculate mass: `Mass = Molarity * Molar Mass * Volume = 0.5 mol/L * 58.44 g/mol * 0.5 L = 14.61 grams`. Dissolve 14.61 g of NaCl in deionized water and bring the total volume to 500 mL.
How does the dilution equation C1V1 = C2V2 work?
The dilution equation `C1 * V1 = C2 * V2` states that the amount of solute remains constant during dilution. `C1` is stock concentration, `V1` is stock volume to pipette, `C2` is desired final concentration, and `V2` is desired final volume. To find required stock: `V1 = (C2 * V2) / C1`.
What is the difference between Molarity (M) and Molality (m)?
Molarity (M) is moles of solute per liter of total solution (mol/L), which varies slightly with temperature due to thermal fluid expansion. Molality (m) is moles of solute per kilogram of pure solvent (mol/kg), which is independent of temperature.
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