Chemistry
pH after dilution
Dilution multiplies the concentration by the ratio of sample volume to total volume. A tenfold dilution raises the pH by exactly one unit.
The Formula
pH_new = -log10([H+] x Vsample / Vtotal)
Dilution multiplies the concentration by the ratio of sample volume to total volume. A tenfold dilution raises the pH by exactly one unit.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| Vs | Sample volume | litres | Volume of the solution being diluted. |
| Vtot | Total volume | litres | Sample volume plus the water added. |
| pH | New pH | dimensionless | Rises by one unit for each tenfold dilution. |
What Each Symbol Means
Vslitres
Sample volume
Volume of the solution being diluted.
Vtotlitres
Total volume
Sample volume plus the water added.
pHdimensionless
New pH
Rises by one unit for each tenfold dilution.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate ph page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate pH, filed under Science. Every number the guide produces comes from substituting into this one line.