Solution Preparation Calculator

Calculate the mass of solute or volume of stock solution needed to prepare a target concentration solution. Step-by-step instructions for laboratory solution preparation.

🧪 Solutions📐 m = M × V × Mw (from solid)🧪 Chemistry
Target concentration (mol/L)
Target volume V (mL)
Molar mass of solute Mw (g/mol)
Stock concentration (M, if using stock)
Prepare from:
Please enter valid values.

Formula & Reference

VariableSymbolFormulaUnits
Solution Preparation Calculator—m = M × V × Mw (from solid)g or mL

Step-by-Step Examples

Example 1
From Solid NaCl

Prepare 500 mL of 0.250 M NaCl (Mw=58.44).

  • m = C x V x Mw = 0.250 x 0.500 x 58.44 = 7.305 g
  • Weigh 7.305 g NaCl
  • Dissolve in ~400 mL water, transfer to 500 mL volumetric flask
  • Dilute to 500 mL mark
✓ Weigh 7.305 g NaCl, dilute to 500 mL
Example 2
From Stock HCl

Prepare 250 mL of 0.100 M HCl from 12.0 M stock.

  • Vs = C*V/Cs = 0.100*250/12.0 = 2.08 mL
  • Pipette 2.08 mL of 12.0 M HCl into 250 mL flask
  • Add water to the 250 mL mark (add acid to water!)
✓ 2.08 mL of 12 M HCl diluted to 250 mL
Example 3
Buffer Preparation

Prepare 1.00 L of 0.100 M sodium acetate. Mw=82.03.

  • m = 0.100 x 1.00 x 82.03 = 8.203 g
  • Dissolve in ~900 mL water, adjust pH if needed
  • Transfer to 1 L volumetric flask, dilute to mark
✓ 8.203 g sodium acetate dissolved to 1.00 L

Real-World Applications

🧪
Research Lab
Every quantitative experiment starts with precisely prepared reagent solutions.
💊
Pharmacy
Drug stock solutions prepared at exact concentration for dilution to patient doses.
🏭
Industrial Chemistry
Process reagents prepared from concentrated stocks using dilution calculations.
🔬
Analytical Chemistry
Calibration standards prepared from primary standards to known concentrations.

Common Mistakes to Avoid

⚠️
Use volumetric flasks for precision

Volumetric flasks (100, 250, 500, 1000 mL) are calibrated to contain exact volume at 20 C. Fill to the calibration line.

⚠️
Add acid to water, not water to acid

When diluting concentrated acids (HCl, H2SO4): add acid slowly to water while stirring. Never reverse. Exothermic reaction can splash if reversed.

⚠️
Weigh to 4 significant figures

Use analytical balance (4 decimal places in grams). Volumetric errors often dominate at < 4 sig figs.

Frequently Asked Questions

What is a primary standard? ▾
A substance with known high purity (>99.95%) used to prepare solutions of known exact concentration. Examples: KHP (potassium hydrogen phthalate), Na2CO3.
What is a volumetric flask? ▾
Calibrated glassware with a line on the neck. Contains exactly the stated volume at 20 C. Use to prepare precise concentrations.
What is the SOP for making a solution? ▾
Weigh solute. Dissolve in partial volume of solvent (avoid heat of dissolution issues). Cool to room T. Transfer to volumetric flask. Dilute to calibration line.
Why cool before filling to the mark? ▾
Volume depends on temperature. Hot solutions are expanded. Cooling to room T before filling ensures accurate volume at the reference temperature (20 C).
What is a working standard? ▾
A solution prepared from a more concentrated stock at a known dilution. Prepared fresh from stock standards. Used for daily calibrations in analytical work.

Related Chemistry Calculators

💧 Dilution C1V1=C2V2🧪 Molarity⚗️ Molar Mass💧 Serial Dilution🧪 Normality

Formula Explorer connections

Interpretation: This formula connects solute amount and solution volume, mass or particle count to concentration and colligative behavior. Assumption: Distinguish solution volume from solvent volume, use the stated temperature, and account for dissociation or nonideal activity when required.

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