Calculator Form
The page stays in a single centered column, while inputs shift to 3 columns on large screens, 2 on medium screens, and 1 on mobile.
Example Data Table
| Scenario | Inputs | Result |
|---|---|---|
| NaCl molarity | 5.844 g NaCl, 58.44 g/mol, 1 L solution | 0.1 mol/L |
| Sucrose molality | 34.23 g sucrose, 342.3 g/mol, 500 g solvent | 0.2 mol/kg |
| Acid normality | 4.9 g acid, 49 g/mol, n-factor 1, 100 mL | 1 N |
| Mass/volume mix | 10 g solute, 250 mL solution | 4% w/v |
| Dilution target | 2 M stock, 0.25 M target, 500 mL final volume | 62.5 mL stock + 437.5 mL diluent |
Formula Used
Molarity
M = n / V, where n = mass / molecular weight and V is solution volume in liters.
Molality
m = n / kg solvent. This method uses solvent mass, so it remains reliable when temperature changes alter volume.
Normality
N = equivalents / L, and equivalents = moles × n-factor. Equivalent weight is molecular weight / n-factor.
Percent Concentrations
% w/w = (solute mass / solution mass) × 100, % v/v = (solute volume / solution volume) × 100, and % w/v = grams per 100 mL.
Dilution
C1V1 = C2V2. Solve for the required stock volume, then subtract from final volume to get diluent volume.
Trace Levels
ppm ≈ mg/L and ppb ≈ ug/L for dilute aqueous solutions. Density can improve mass-basis estimates.
How to Use This Calculator
- Select the concentration mode that matches your problem.
- Enter the required mass, moles, volume, or dilution values.
- Choose the correct units for every field.
- Add molecular weight or n-factor when the mode needs them.
- Optionally provide density for better mass-volume interpretation.
- Press Calculate Concentration to show results above the form.
- Review the chart, summary table, and export buttons.
- Download CSV or PDF for lab records, teaching notes, or project files.
FAQs
1) When should I use molarity instead of molality?
Use molarity when solution volume is known and reporting is volume-based. Use molality when solvent mass is known or temperature changes could affect solution volume.
2) Why does molecular weight matter?
Molecular weight converts solute mass into moles. Without that conversion, the calculator cannot determine molarity, molality, or normality from mass inputs.
3) What is the difference between normality and molarity?
Molarity counts moles per liter. Normality counts equivalents per liter, so it depends on the specific reaction and the selected n-factor.
4) Can I use ppm and ppb for any solution?
Yes, but the common shortcuts ppm ≈ mg/L and ppb ≈ ug/L are most reliable for dilute, water-like solutions. Density improves interpretation when the mixture differs from water.
5) Why must stock concentration exceed target concentration in dilution mode?
A dilution lowers concentration by adding solvent. If the stock is weaker than or equal to the target, simple dilution cannot create the desired stronger mixture.
6) What does % w/v actually mean?
% w/v means grams of solute per 100 mL of final solution. It is widely used in laboratory and pharmaceutical preparation work.
7) Should I enter solvent volume or solution volume?
For molarity and many practical preparations, use final solution volume. For molality, use solvent mass instead of total volume because molality is mass-based.
8) What are the best units to use?
Use units that match your lab data. The calculator converts common mass, volume, and mole units automatically, but you should still verify your source measurements carefully.