Calculate buffer mass/volume concentration, solute mass, or solution volume from any two values in g, kg, lb, L, mL, or US gal units.
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Buffer Concentration (Mass/Volume) Formula
The buffer concentration by mass and volume is the mass of dissolved solute divided by the total solution volume. The calculator uses grams and liters as its base units, then converts the result to the unit you select.
C = m/V
m = C*V
V = m/C
- C = mass concentration of the buffer solution
- m = solute mass
- V = solution volume
The calculator has three functions:
- Calculate concentration: enter solute mass and solution volume. The calculator uses C = m/V.
- Calculate solute mass: enter concentration and solution volume. The calculator uses m = C*V.
- Calculate solution volume: enter solute mass and concentration. The calculator uses V = m/C.
For consistency, mass is converted to grams, volume is converted to liters, and concentration is calculated in g/L before being converted to g/L, g/mL, kg/L, or lb/US gal.
Mass, Volume, and Concentration Unit Conversions
These are the unit conversions used when changing between the calculator’s supported units.
| Quantity | Unit | Base conversion |
|---|---|---|
| Mass | g | 1 g |
| Mass | kg | 1 kg = 1000 g |
| Mass | lb | 1 lb = 453.59237 g |
| Volume | mL | 1 mL = 0.001 L |
| Volume | L | 1 L |
| Volume | US gal | 1 US gal = 3.785411784 L |
| Concentration unit | Equivalent in g/L | Common meaning |
|---|---|---|
| g/L | 1 g/L | Grams of solute per liter of solution |
| g/mL | 1000 g/L | Grams of solute per milliliter of solution |
| kg/L | 1000 g/L | Kilograms of solute per liter of solution |
| lb/US gal | 119.826427316 g/L | Pounds of solute per US gallon of solution |
Example Calculations
Example 1: Calculate buffer concentration
You dissolve 25 g of solute and prepare a final solution volume of 0.5 L.
C = m/V
C = 25/0.5 = 50 g/L
The buffer concentration is 50 g/L.
Example 2: Calculate solute mass
You need 2 L of buffer at a concentration of 10 g/L.
m = C*V
m = 10*2 = 20 g
You need 20 g of solute.
FAQ
Is mass/volume concentration the same as molarity?
No. Mass/volume concentration gives the mass of solute per solution volume, such as g/L. Molarity gives moles of solute per liter, such as mol/L. To convert from g/L to mol/L, you need the solute’s molar mass.
Should volume mean solvent volume or final solution volume?
Use the final solution volume. For example, if you are making 1 L of buffer, dissolve the solute and then bring the total volume up to 1 L. Do not use only the starting solvent volume unless it is also the final solution volume.
Can concentration be zero?
A zero concentration means no solute per unit volume. You can calculate a zero solute mass from zero concentration, but you cannot calculate volume by dividing by zero concentration. In that case, the volume is undefined.
