Buffers
How do you calculate buffer builder?
Build a multi-component buffer from stocks and solids. The relationship used is per component: C1V1 = C2V2, or mass = C x V x MW.
Worked example
Every number below is computed by the calculator, not typed in
What you are given
- Final volume: 500 mL
- Components: [{"name":"NaCl","target":"150","targetUnit":"mM","sourceKind":"solid","mw":"58.44","stock":"","stockUnit":"M"},{"name":"Tris","target":"50","targetUnit":"mM","sourceKind":"stock","mw":"","stock":"1","stockUnit":"M"}]
Formula: per component: C1V1 = C2V2, or mass = C x V x MW
The working
- NaCl (solid weigh-out):
mass = 0.15 mol/L * 0.5 L * 58.44 g/mol = 4.383 g - Tris (stock dilution):
V1 = (0.05 M / 1 M) * 500 mL = 25 mL - Diluent:
finalVolume - sum(stock volumes) = 500 mL - 25 mL = 475 mL
To make 500 mL of buffer, combine:
Open this example in the calculator
What each symbol means
- m: Mass to weigh out (g)
- C: Target concentration (mol/L)
- V: Final volume (L)
- Mw: Molar mass (g/mol)
A printable one-page version is on the formula sheet.
Do it with your own numbers.
The Buffer builder calculator is free, shows every step, flags the hazards, and works offline once loaded. No account, no signup.
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