Titration Calculator
Calculate the molarity of an unknown acid or base solution using titration data. Features equivalence point pH, indicator recommendations, and step-by-step solutions with titration curve visualization.
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About Titration Calculator
The Titration Calculator determines the molarity of an unknown acid or base solution by analyzing titration data. Enter your titrant and analyte information, and the calculator provides the unknown concentration, equivalence point pH, recommended indicators, step-by-step solutions with formulas, and an interactive titration curve. It supports polyprotic acids, polybasic bases, and both strong and weak acid-base combinations.
The Titration Equation
All acid-base titration calculations are based on the stoichiometric relationship at the equivalence point:
Where \(M\) is molarity (mol/L), \(V\) is volume (mL), and \(n\) is the number of replaceable H⁺ or OH⁻ ions per formula unit.
How to Use This Calculator
- Select calculation mode: Choose "Find Unknown Molarity" if you know the volume of titrant used at equivalence, or "Find Equivalence Volume" if you know both concentrations.
- Enter titrant information: Specify whether the titrant is an acid or base, then enter its molarity. For Find Molarity mode, also enter the volume used at the equivalence point.
- Enter analyte information: Provide the analyte volume. For Find Volume mode, also enter the analyte molarity.
- Set advanced options (optional): Adjust the number of equivalents for polyprotic acids or polybasic bases. Set acid/base strength and provide Ka or Kb for more accurate equivalence point pH calculations.
- Review results: Examine the calculated value, step-by-step derivation, equivalence point pH, recommended indicators, and the titration curve.
Understanding Equivalence Point pH
| Titration Type | Equivalence pH | Recommended Indicator |
|---|---|---|
| Strong Acid + Strong Base | = 7.0 (neutral) | Bromothymol Blue, Phenolphthalein |
| Weak Acid + Strong Base | > 7.0 (basic) | Phenolphthalein |
| Strong Acid + Weak Base | < 7.0 (acidic) | Methyl Orange, Methyl Red |
| Weak Acid + Weak Base | Depends on Ka/Kb | Varies |
Common Titration Examples
Strong Acid–Strong Base: HCl + NaOH
Hydrochloric acid reacting with sodium hydroxide is the simplest titration. Both are monoprotic/monobasic, so \(n_a = n_b = 1\). The equivalence point pH is exactly 7.0, and the pH changes sharply near the equivalence point, making it easy to detect with almost any indicator.
Diprotic Acid: H₂SO₄ + NaOH
Sulfuric acid donates 2 protons per molecule (\(n_a = 2\)), so it requires twice the moles of NaOH (\(n_b = 1\)) to reach the equivalence point. The general equation becomes \(2 \times M_a \times V_a = 1 \times M_b \times V_b\).
Weak Acid: CH₃COOH + NaOH
Acetic acid (\(K_a = 1.8 \times 10^{-5}\)) titrated with NaOH produces a basic equivalence point (pH ≈ 8.7). The buffer region before equivalence follows the Henderson–Hasselbalch equation, and at half-equivalence, pH = pKa = 4.74.
Frequently Asked Questions
What is titration and how does it work?
Titration is a quantitative analytical technique used to determine the concentration of an unknown solution (the analyte) by reacting it with a solution of known concentration (the titrant). The titrant is added gradually until the reaction reaches the equivalence point, where the moles of acid equal the moles of base.
What is the equivalence point in a titration?
The equivalence point is the moment during a titration when the amount of titrant added is stoichiometrically equivalent to the amount of analyte in the solution. At this point, all the analyte has reacted completely with the titrant. The pH at the equivalence point depends on the strengths of the acid and base involved.
How do I choose the right indicator for a titration?
Choose an indicator whose color change range (pH transition interval) includes the pH at the equivalence point. For strong acid–strong base titrations (equivalence pH 7), bromothymol blue or phenolphthalein work well. For weak acid–strong base titrations (equivalence pH above 7), phenolphthalein is ideal. For strong acid–weak base titrations (equivalence pH below 7), methyl orange or methyl red are recommended.
What is the difference between equivalence point and endpoint?
The equivalence point is the theoretical point where the moles of acid exactly equal the moles of base. The endpoint is the point at which the indicator changes color, signaling that the equivalence point has been reached. Ideally, the endpoint should be as close to the equivalence point as possible, which is why choosing the correct indicator is important.
Can this calculator handle polyprotic acids like H₂SO₄ or H₃PO₄?
Yes, this calculator supports polyprotic acids and polybasic bases. You can set the number of replaceable hydrogen ions (for acids) or hydroxide ions (for bases) using the equivalents selector. For example, set n=2 for sulfuric acid (H₂SO₄) which donates 2 protons per molecule, or n=3 for phosphoric acid (H₃PO₄).
Reference this content, page, or tool as:
"Titration Calculator" at https://MiniWebtool.com/titration-calculator/ from MiniWebtool, https://MiniWebtool.com/
by miniwebtool team. Updated: Mar 16, 2026
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