What is it?
The Molarity & Dilution Calculator helps you make solutions: choose what I want to do.
Who is it for?
Chemistry and biology students, lab technicians and teachers preparing solutions.
How to use it
- Under I want to, choose Find molarity from mass, Find the mass to weigh out or Dilute a solution (C1V1 = C2V2).
- Fill in the boxes that appear for that choice.
- Read the answer below the boxes.
Three tasks
- Find molarity from mass: enter the Mass dissolved, Molar mass and Volume of solution.
- Find the mass to weigh out: enter the Molarity wanted, volume and molar mass. Mass = molarity × volume (L) × molar mass. Dissolve, then make it up to the final volume.
- Dilute a solution (C1V1 = C2V2): enter the Stock concentration (C1), Concentration wanted (C2) and Volume wanted (V2). Read the Stock solution to take (V1) and Water to add.
Don’t know the molar mass? Find it with our Molar Mass Calculator.
Lab practice
- Dissolve in less water than the final volume, then make up to the mark in a volumetric flask. Adding the solid to the full volume gives a slightly lower concentration.
- Use the molar mass of the exact form you have: hydrated salts (like CuSO4·5H2O) weigh more per mole than anhydrous ones.
- Diluting acids: always add acid to water, never water to acid.
Worked example
To make 250 ml of 0.1 M NaCl (58.44 g/mol): 0.1 × 0.25 × 58.44 = 1.46 g, made up to 250 ml.
Errors and how to fix them
- “The concentration wanted must be lower than the stock”: dilution can only lower concentration.
Open the tool: Molarity & Dilution Calculator
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Questions, or an error not listed here?
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