Titration Calculator
Acid-base titration unknown from molarity, volume, and mole ratio.
What it does
Titration finds an unknown strength by reacting a measured volume to completion with a known standard. At the equivalence point the mole counts stand in the ratio of the balanced equation, so one division exposes the missing concentration or volume.
The tool above takes acid and base concentrations with volumes plus both coefficients. Zero out exactly one of the four fields to solve it. The default finds acid strength from 25 mL acid against 12.5 mL of 0.1 M base at 1:1, giving 0.05 M.
Steps match LibreTexts with a university lab manual beside them: moles equal moles at equivalence for 1:1 pairs, moles equal M times liters, and polyprotic cases scale by coefficients. Checked vectors agree, from 0.5 M base over 20.70 mL into 15 mL acid at 0.69 M to the sulfuric 2:1 case at 0.151 M.
Indicators mark the endpoint while math marks equivalence, and the two coincide only with the right indicator. Overshooting the color change overstates titrant volume, so slow near the end and read the burette at eye level.
How to use
- Balance the neutralization equation first.
- Type both coefficients from it.
- Type the three known values.
- Type 0 in the unknown field.
- Read answer first, moles beside it.
- Confirm units: M with mL cancels cleanly.
Formula
- Ma, Mb
- Acid and base molarities.
- Va, Vb
- Volumes in mL; ratio cancels units.
- na, nb
- Balanced equation coefficients.
Volumes convert to liters inside mole math but cancel in ratios, so mL works throughout. Exactly one zero allowed; more means underdetermined.
Worked example
Example: find 25 mL acid strength
Defaults: Va 25 mL, Cb 0.1 M, Vb 12.5 mL, 1:1.
- Moles base: 0.1 x 0.0125 L = 0.00125 mol.
- Ratio 1:1 keeps 0.00125 mol acid.
- Divide: 0.00125 / 0.025 L = 0.05 M.
- Shortcut: 0.1 x 12.5 / 25 = 0.05 M.
- Tool shows 0.05 M with 0.00125 mol each side.
Reference table
| Knowns | Solve | Answer |
|---|---|---|
| 0.5 M base 20.70 mL, acid 15 mL, 1:1 | Ma | 0.69 M |
| 0.1 M acid 50 mL, 0.2 M base, 1:1 | Vb | 25 mL |
| 0.25 M base 32.2 mL, acid 26.6 mL, 1:2 | Ma | 0.151 M |
| 0.1 M acid 20 mL, base 18.47 mL, 1:2 | Mb | 0.217 M |
| 0.75 M base 10 mL, 0.25 M acid, 1:1 | Va | 30 mL |
Limits
- Equivalence assumed; bad endpoints skew.
- Strong pair math; weak pairs need Ka curves.
- Coefficients must come first.
- One unknown only per run.
Common mistakes
- Using 1:1 on diprotic H2SO4.
- Mixing liters and milliliters mid formula.
- Reading the burette from above.
- Blowing past the endpoint color.
- Solving with two fields zeroed.
Try it yourself
Quick checks. Answers sit tucked under each question.
0.5 M base 20.70 mL into 15 mL acid?
Ma 0.69 M.
0.1 M acid 50 mL with 0.2 M base?
Vb 25 mL.
Sulfuric 26.6 mL vs 32.2 mL of 0.25 M base?
Ma 0.151 M at 1:2.
Questions
What does the default solve?
Acid strength 0.05 M from 25 mL against 12.5 mL of 0.1 M base.
How do I solve volume instead?
Zero the volume field and type the concentration.
Diprotic acids?
Set coefficients, such as 1 and 2 for H2SO4 with NaOH.
Endpoint versus equivalence?
Color change versus mole equality; right indicator aligns them.
mL or L?
Either in ratios; moles use liters inside.
Two unknowns?
Rejected: zero out exactly one field.