1Solution Preparation
Uses the same Mw above. Enter any 2 values below to solve the third.
Molality uses solvent mass instead of final solution volume, so it stays stable across temperature-driven volume changes.
Input formula to get Mw
Enter the pair you know best
The final field solves automatically
2Dilution
Calculation Results
Calculation Formulas
- Mass (m): The mass of the solute in grams (g).
- Molar Mass (Mw): The mass per mole of substance (g/mol).
- Volume (V): The final solution volume used in molarity calculations.
- Molarity (C): Moles of solute per liter of solution.
- Molality (b): Moles of solute per kilogram of solvent.
- Solvent Mass (W): The solvent-only mass used in molality calculations, not total solution mass.
Scientific Knowledge Base
Molarity (M)
Molarity is moles per liter of solution, which makes it ideal for volumetric preparation and dilution.
Molality (b)
Molality uses solvent mass instead of total volume, so it is more stable when temperature shifts the solution volume.
Dilution Principle
Dilution only adds solvent, so the moles of solute stay constant before and after the dilution step.
When to use which
Use molarity for final-volume prep, molality for solvent-mass prep, and C1V1=C2V2 for stock solution dilution.
Typical Workflows
This calculator is designed for the two chemistry tasks that come up most often in class and in routine lab prep: making a new solution from a target concentration, and diluting an existing stock to a lower concentration.
- Use the molarity mode when a protocol specifies final solution volume.
- Use the molality mode when the solvent mass matters more than the final expanded volume.
- Use the dilution helper when you already have a stock bottle and need the correct transfer volume.
A common workflow is preparing 500 mL of a 0.1 M solution from a known molar mass, then checking a separate dilution from a concentrated stock using the C1V1 = C2V2 relationship.
Frequently Asked Questions
What is the practical difference between molarity and molality?
Molarity is based on final solution volume, while molality is based on solvent mass. Molality is often preferred when temperature-driven volume changes could affect interpretation.
When should I trust the dilution helper?
Use it when concentration basis is consistent on both sides of the dilution. If your stock label uses a different basis than your target, convert the basis first and then run the dilution.
Why is molar mass so important here?
Because every concentration calculation depends on converting between grams and moles. If the molar mass is wrong, the rest of the workflow will also be wrong even if the arithmetic looks clean.