Molarity to Mass Calculator

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Example data table

These examples show typical lab mixes and the mass of solute needed.

Formula used

How to use this calculator

1. Enter molarity and select the correct molarity unit.
2. Enter solution volume and choose its unit.
3. Enter molar mass for the solute, then unit.
4. Select the output mass unit you prefer.
5. Set significant figures and enable steps if needed.
6. Press Calculate to see mass above the form.
7. Use CSV or PDF buttons to export your results.

Recent calculations

No history yet. Run a calculation to store it here.

Use these notes to plan reagents, validate results, and avoid common unit mistakes.

1) What the calculator returns

When you know the target concentration and final volume, the calculator outputs the solute mass to weigh. It also reports the intermediate moles, which helps you verify stoichiometry, scale batches, and compare multiple recipes without redoing the math.

2) Inputs that control the outcome

You must enter molarity, solution volume, and molar mass. Molar mass depends on the exact chemical form. Common references include NaCl = 58.44 g/mol, KCl = 74.55 g/mol, and glucose = 180.16 g/mol. A wrong molar mass directly produces a wrong mass.

3) The two-step chemistry math

First compute moles using n = M × V, with M in mol/L and V in liters. Then compute grams using m = n × MM, where MM is in g/mol. Output units are converted after the gram value is found.

4) Unit data you should remember

Most errors come from volume units. Use 1 L = 1000 mL and 1 mL = 1 cm³. For large tanks, 1 m³ = 1000 L. For US measures, 1 US gallon ≈ 3.7854 L, and 1 fl oz ≈ 0.02957 L.

5) Typical ranges and sanity checks

Many buffers and salts are prepared from 0.001 to 1.0 mol/L, while concentrated stocks may reach 2–10 mol/L if solubility allows. If your answer is unexpectedly tiny or huge, confirm you did not choose mmol/L instead of mol/L, and re-check the volume unit.

6) Example you can verify manually

For 0.50 mol/L NaCl and 250 mL: convert volume to 0.250 L, then moles are 0.50 × 0.250 = 0.125 mol. Multiply by 58.44 g/mol to get 7.305 g. The example table includes this value for comparison.

7) Practical weighing tips

Match significant figures to your equipment. A 0.1 mg balance does not require excessive decimals. Weigh the solute, dissolve in less solvent, then bring to the final mark in volumetric glassware. This “make up to volume” approach improves accuracy for molarity targets.

8) Documentation and exports

Save outputs for traceability. CSV is ideal for spreadsheets and batch sheets, while the PDF summary fits lab notebooks and SOP attachments. The history table keeps recent mixes visible so repeated preparations are faster and less prone to transcription errors.

FAQs

1) What is molarity?

Molarity is moles of solute per liter of final solution, written as mol/L. It describes concentration for a specified volume.

2) Why does molar mass matter?

Molarity gives moles, but a balance measures mass. Molar mass converts moles into grams so you can weigh the correct amount.

3) Is the volume the solvent volume?

Use the final solution volume. Dissolve first, then add solvent until the final volume is reached to achieve the target molarity.

4) What happens if I pick mmol/L by mistake?

mmol/L is 1000× smaller than mol/L. Choosing the wrong unit shifts moles and mass by a factor of 1000.

5) Can I use this for hydrates?

Yes. Use the hydrate’s molar mass (for example, CuSO₄·5H₂O) because the water of crystallization changes g/mol and the mass needed.

6) How do I get mg instead of g?

Select mg as the output unit. The calculator computes grams internally and then converts to mg using fixed conversion factors.

7) How can I check the answer quickly?

Convert volume to liters, multiply by molarity to get moles, then multiply by molar mass to get grams. Compare with the shown steps.