Concentration Calculator

Molarity · Mass Percent · ppm · ppb | Chemistry Solution Tool

Result

📝 Step-by-step solution

Select mode and enter values

💡 M = mol/L | Mass % = (mass solute / mass solution) × 100 | ppm = mg/L | ppb = µg/L

📖 What is Concentration?

Concentration describes how much solute is dissolved in a given amount of solvent or solution. Different situations call for different concentration units — molarity for chemical reactions, mass percent for industrial mixtures, and ppm/ppb for trace contaminants.

🧮 Concentration Formulas

Molarity (M): M = moles of solute / liters of solution
Mass Percent (w/w): % = (mass of solute / mass of solution) × 100
ppm: ppm = (mass of solute / mass of solution) × 10⁶
ppb: ppb = (mass of solute / mass of solution) × 10⁹

📝 Worked Examples

Example 1: Molarity of NaCl Solution

Given: 0.5 mol NaCl dissolved in 0.25 L water
Formula: M = n / V
Calculation: M = 0.5 / 0.25 = 2.0 M

Example 2: Mass Percent

Given: 10 g salt in 90 g water (total = 100 g)
Formula: % = (10 / 100) × 100
Calculation: 10% w/w NaCl solution

Example 3: ppm

Given: 5 mg of fluoride in 1 L of water (1 L ≈ 1000 g)
Formula: ppm = (5 mg / 1000 g) × 10⁶
Calculation: 5 ppm

📊 When to Use Each Unit

Molarity (M): Chemistry labs, reaction stoichiometry, titrations.
Mass %: Industrial chemicals, cleaning solutions, alloys.
ppm: Water quality, air pollutants, trace minerals.
ppb: Ultra-trace contaminants, pesticides, heavy metals.

⚠️ Limitations & Assumptions

📌 Important Notes

Assumes solution temperature is constant (density changes with temperature).
Molarity uses volume of solution, not volume of solvent.
ppm and ppb assume dilute aqueous solutions (1 mL ≈ 1 g).
Does not account for dissociation, activity coefficients, or non-ideal behavior.
Results are theoretical estimates — verify with lab measurements.

📚 Sources & References

Authoritative Sources

OpenStax — Chemistry 2e (Chapter on Solutions)
IUPAC — Compendium of Chemical Terminology
NIST — Chemistry WebBook
CRC Handbook of Chemistry and Physics

❓ Frequently Asked Questions

What is the difference between molarity and molality?

Molarity (M) is moles of solute per liter of solution. Molality (m) is moles of solute per kilogram of solvent. Molality is temperature-independent while molarity changes with temperature.

How do I convert ppm to mg/L?

For dilute aqueous solutions, 1 ppm ≈ 1 mg/L. This is because 1 L of water weighs approximately 1 kg.

Can I use mass percent for gases?

Yes, but for gases volume percent or mole percent are more common. Mass percent is usually used for liquids and solids.

What does "w/w" mean?

"w/w" means weight by weight — the mass of solute divided by the total mass of solution. Other variants: v/v (volume by volume), w/v (weight by volume).

🔗 Related Calculators

⚠️ Disclaimer

This Concentration Calculator is provided for informational and educational purposes only. Results are based on standard chemistry formulas and assumed ideal conditions. Real-world values may differ due to temperature, dissociation, impurities, and non-ideal behavior. Always verify critical calculations with laboratory measurements or authoritative references.