Formula Used
Solution density: density = specific gravity × reference water density.
Solution mass per liter: mass per liter = solution density × 1000.
Solute mass per liter: solute g/L = solution g/L × mass percent ÷ 100.
Molarity: molarity = solute g/L ÷ molar mass. Reported molarity also uses the dilution factor.
Molality: molality = moles of solute per liter ÷ kilograms of solvent per liter.
Normality: normality = molarity × valence factor.
How to Use This Calculator
Enter the measured specific gravity of the solution. Add the water density used as reference. Use 0.997 g/mL for water near 25 C when no better value is available.
Enter the solute mass percent as weight by weight. Add the solute molar mass from its formula. Set valence for equivalent concentration. Set particle factor for estimated osmolarity.
Press calculate. The result appears above the form and below the header. Use the CSV or PDF buttons to save the completed result.
Example Data Table
| Solution |
Specific Gravity |
Mass Percent |
Molar Mass |
Approx Molarity |
| Hydrochloric acid |
1.19 |
37 |
36.46 g/mol |
12.08 mol/L |
| Sodium hydroxide |
1.53 |
50 |
40.00 g/mol |
19.13 mol/L |
| Sodium chloride brine |
1.07 |
10 |
58.44 g/mol |
1.83 mol/L |
Article
Physical Meaning
Specific gravity compares a solution density with water. That ratio helps estimate how much solution mass fits inside one liter. When mass percent is known, the solute mass in that liter becomes clear. Dividing that mass by molar mass gives moles per liter. This is molar concentration, also called molarity.
Why This Method Helps
Many lab sheets list density or specific gravity instead of molarity. This happens with acids, bases, brines, syrups, and industrial liquids. A direct conversion saves time. It also keeps units visible. The calculator uses a density basis first. Then it converts mass concentration into chemical amount concentration.
Inputs That Matter
Specific gravity must be measured at a temperature. Water density changes with temperature. So the reference density field is included. Mass percent should be weight by weight. Molar mass must match the solute formula. Valence is used for normality. Particle factor is used for estimated osmolarity. Dilution factor lets you scale a prepared sample back to stock strength.
Interpreting Results
Molarity reports moles of solute per liter of solution. Molality reports moles per kilogram of solvent. Normality reports equivalents per liter. It depends on reaction type, so choose valence carefully. Mole fraction describes the share of solute particles by moles. Each value answers a different physical question.
Best Practice
Use fresh density data. Use a calibrated hydrometer or density meter. Confirm that the percent value is not volume percent. Check molar mass from the exact formula. For concentrated mixtures, volume contraction can make simple assumptions less accurate. Still, the density based method is useful for quick estimates, process checks, and teaching.
Physics Context
Concentration links mass density with molecular scale counting. It connects continuum measurements to particle amount. That makes it useful in transport, buoyancy, osmotic pressure, diffusion, and fluid property work. Specific gravity is easy to measure. Molarity is easier to use in equations. This tool bridges both viewpoints.
Quality Checks
Repeat measurements when the liquid is warm, foamy, or not mixed. Remove bubbles before reading the meniscus. Record the temperature beside every value. Round final answers only after calculation. Compare results with supplier data when possible. Large differences usually mean wrong percent type, wrong reference density, or an unsuitable molar mass.
FAQs
What is molar concentration?
Molar concentration is moles of solute per liter of solution. It is often called molarity. It helps compare chemical strength by particle amount, not only by mass.
How does specific gravity help find molarity?
Specific gravity gives solution density when multiplied by water density. Density gives grams of solution per liter. Mass percent then gives solute grams per liter.
Should I use mass percent or volume percent?
This calculator uses mass percent by weight. Do not enter volume percent unless you first convert it into weight percent using reliable density data.
What water density should I enter?
Use the water density that matches the measurement temperature. If no exact value is known, 0.997 g/mL is a common estimate near 25 C.
What is the valence factor?
The valence factor converts molarity into normality. It depends on the reaction. For example, sulfuric acid can have a factor of 2 in acid-base work.
What is the particle factor?
The particle factor estimates how many dissolved particles form per formula unit. Sodium chloride is often estimated as 2, while nonelectrolytes often use 1.
Why is molality different from molarity?
Molarity uses liters of solution. Molality uses kilograms of solvent. Molality is useful when temperature changes because mass does not expand like volume.
Can this replace laboratory analysis?
No. It provides a density based estimate. Use calibrated measurements, correct temperature data, and verified composition for formal lab or industrial reporting.