Titration Calculator
Find an unknown concentration or volume at the equivalence point, and the pH during a strong acid and strong base titration, with every step shown.
What this calculator does
Use the equivalence-point relation to solve for the analyte volume or concentration, and compute the pH before, at and after the equivalence point.
When you need it
Titration is the standard way to find the concentration of an acid or base in the lab. The same calculation is used in quality control for food, water and pharmaceuticals.
Formulas
- At equivalence: Ma · Va = Mb · Vb (for a 1:1 reaction)
- Before equivalence: [H⁺] = excess moles of acid ÷ total volume
- After equivalence: [OH⁻] = excess moles of base ÷ total volume
How to use it
- Enter the concentration and volume of the titrant and the volume or concentration of the analyte.
- Choose what to solve for.
- Read the equivalence point and the pH at each stage.
Worked example
20.0 mL of 0.150 M NaOH neutralizes 25.0 mL of HCl. What is the concentration of the HCl?
- Moles of NaOH = 0.150 M × 0.0200 L = 0.00300 mol
- At equivalence, moles of HCl = 0.00300 mol
- [HCl] = 0.00300 mol ÷ 0.0250 L = 0.120 M
Answer
The HCl is 0.120 M.
Common mistakes
- Using Ma·Va = Mb·Vb when the acid and base react in a ratio other than 1:1.
- Mixing mL and L.
- Assuming the pH at equivalence is 7 for a weak acid or weak base.
Related tools
Frequently asked questions
What is the equivalence point?
The point where the moles of titrant added exactly equal the moles of analyte, according to the balanced equation.
Is the pH 7 at the equivalence point?
For a strong acid with a strong base, yes. For a weak acid with a strong base the pH is above 7.
What is the difference between the endpoint and the equivalence point?
The endpoint is when the indicator changes color. It should be as close as possible to the equivalence point.