Molarity Calculator
Calculate Molarity, Moles & Solution Concentration - Complete Chemistry Tool
🧪 Pro Tips for Molarity Calculations:
Molarity = moles / liters of solution. Use molecular weight to convert mass to moles. Measure total solution volume (not just solvent). Temperature affects volume - standard is 25°C. Use volumetric flasks for accurate measurements. Always record actual concentration, not just calculated value. Account for solute solubility limits.
Calculate Molarity from Mass and Volume
✅ Molarity Calculation Results:
Calculate Moles from Mass
✅ Moles Calculation Results:
Calculate Volume for Specific Molarity
✅ Volume Calculation Results:
Solution Dilution Calculator
✅ Dilution Calculation Results:
Molarity Reference & Common Solutions
Common Compound Molecular Weights:
| Compound | Formula | MW (g/mol) | Common Uses |
|---|---|---|---|
| Sodium Chloride | NaCl | 58.44 | Buffer, saline solutions |
| Potassium Nitrate | KNO₃ | 101.10 | Analytical chemistry |
| Hydrochloric Acid | HCl | 36.46 | Titrations, lab standard |
| Sodium Hydroxide | NaOH | 40.00 | Titrations, pH adjustment |
| Glucose | C₆H₁₂O₆ | 180.16 | Biological solutions |
| Ethanol | C₂H₅OH | 46.07 | Lab solvent |
| Acetic Acid | CH₃COOH | 60.05 | Buffer solutions |
| Sulfuric Acid | H₂SO₄ | 98.08 | Lab reagent |
Solution Preparation Guidelines:
Standard Solution Concentrations:
- Very Dilute: 0.001 M - 0.01 M (analytical work)
- Dilute: 0.01 M - 0.1 M (common lab)
- Standard: 0.1 M - 1 M (typical preparations)
- Concentrated: 1 M - 10 M (stock solutions)
- Very Concentrated: 10M+ (industrial)
- Use volumetric flasks for accurate measurements
- Dissolve in small volume, then dilute to mark
- Allow temperature equilibration (25°C standard)
- Mix thoroughly before use or storage
- Label with concentration, date, preparer
- Store in appropriate containers for chemical
🧪 Understanding Molarity & Solution Concentration
What is Molarity?:
Molarity (M), also called molar concentration, measures amount of solute dissolved per liter of total solution. SI-derived unit: mol/L or M. Fundamental concept in chemistry for controlling precise quantities in reactions and experiments. Temperature-dependent (volume changes with temperature). Standard reference: 25°C (298.15 K).
Key Relationships:- Molarity Formula: M = n/V (moles per liter)
- Using Molecular Weight: M = (mass/MW) / volume
- Dilution Formula: M₁V₁ = M₂V₂ (moles conserved)
- Density Relationship: Different compounds at same molarity have different densities
- Calculate mass needed: m = M × V × MW
- Weigh solute on analytical balance
- Dissolve in small volume of solvent
- Transfer completely to volumetric flask
- Rinse container and add rinse to flask
- Fill to mark with solvent (near eye level)
- Cap and invert 10-15 times to mix
- Allow temperature equilibration
- Label with molarity, date, and initials
- Laboratory: Analytical procedures, reactions, titrations
- Pharmaceutical: Drug formulation, IV solutions
- Industrial: Chemical manufacturing, quality control
- Biology: Culture media, enzyme assays, buffers
- Education: Chemistry experiments, demonstrations
- Solute: Substance being dissolved (usually solid)
- Solvent: Dissolving medium (usually liquid, often water)
- Solution: Homogeneous mixture of solute and solvent
- Molar Mass: Mass of one mole (g/mol), numerically equals MW
- Mole: 6.022 × 10²³ particles (Avogadro's number)
- Stock Solution: Concentrated solution for dilution
❓ Frequently Asked Questions
How do you prepare 100 mL of 1 M NaCl solution?
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Calculate: m = 1 M × 0.1 L × 58.44 g/mol = 5.844 g. Weigh 5.844 g NaCl. Dissolve in small amount water. Transfer to 100 mL volumetric flask. Rinse container and add rinse. Fill to mark with water. Mix thoroughly. Label "1 M NaCl, [date], [initials]."
What's the difference between 1 M and 1 m solution?
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1 M (molarity): 1 mole solute per liter solution. 1 m (molality): 1 mole solute per kilogram solvent. Molarity temperature-dependent; molality temperature-independent. Molarity used in labs; molality in thermodynamics. Same solute gives different numerical values for each unit.
How do you dilute 100 mL of 2 M HCl to 0.5 M?
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Use M₁V₁ = M₂V₂: 2 M × 100 mL = 0.5 M × V₂. V₂ = 400 mL. Take 100 mL of 2 M HCl. Add to volumetric flask (ACID TO WATER). Dilute to 400 mL mark. Mix thoroughly. Result: 400 mL of 0.5 M HCl. Important: NEVER add water to acid - always add acid to water.
Why is volume important in molarity calculations?
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Volume is total solution (solute + solvent), not just solvent. Solute dissolving reduces available volume. Using solvent volume only underestimates molarity. Volumetric flasks deliver exact volume at marked line. Temperature changes volume - standard 25°C. Accurate volume = accurate molarity.
How accurate must molecular weight be?
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Use standard atomic weights from periodic table. Typically 4-6 significant figures. MW directly affects calculated molarity - error compounds. Example: NaCl = 58.44 g/mol (not 58 or 58.5). Use consistent precision throughout calculation. Check multiple sources for unusual compounds.
What's the maximum solubility consideration?
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Some compounds have maximum solubility limits. Can't prepare solution more concentrated than saturation point. Check solubility table for compound in your solvent. Temperature affects solubility - warm solutions dissolve more. Heating during preparation increases solubility. After cooling, excess solute may precipitate.
How to calculate molarity of commercial solutions?
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Use given density and percent composition. Example: 37% HCl, density 1.19 g/mL. Calculate: 1000 mL × 1.19 g/mL × 0.37 = 440 g HCl. Moles = 440 g / 36.46 g/mol = 12.1 M. Commercial solutions often 10-18 M (need dilution for typical use).
