Titration Formula

The Formula

n_A = n_B \implies M_A V_A = M_B V_B

When to use: Slowly adding a known solution to an unknown one until the reaction is just complete — the volume used reveals the concentration.

Quick Example

Adding NaOH solution to HCl of unknown concentration until pH = 7 (equivalence point), then calculating HCl concentration.

Notation

M_A and M_B are the molarities (mol/L) of the analyte and titrant, V_A and V_B are their volumes, and the equivalence point is where n_A = n_B (moles are stoichiometrically equal).

What This Formula Means

A lab technique for finding an unknown solution concentration by gradually adding a solution of known concentration until the reaction is complete.

Slowly adding a known solution to an unknown one until the reaction is just complete — the volume used reveals the concentration.

Formal View

At the equivalence point of an acid-base titration: n_{\text{acid}} \cdot a = n_{\text{base}} \cdot b, where a and b are stoichiometric coefficients. For concentration: c_{\text{analyte}} = \frac{c_{\text{titrant}} \cdot V_{\text{titrant}} \cdot a}{V_{\text{analyte}} \cdot b}.

Common Mistakes

  • Confusing the endpoint with the equivalence point — the endpoint is where the indicator changes color, which may not exactly match the true equivalence point
  • Forgetting to adjust for stoichiometry — if the acid-base ratio is not 1:1 (e.g., \text{H}_2\text{SO}_4 + 2\text{NaOH}), the simple M_AV_A = M_BV_B must be modified
  • Reading the burette incorrectly — the volume is read from the bottom of the meniscus, and parallax errors can lead to inaccurate results

Common Mistakes Guide

If this formula feels simple in isolation but keeps breaking during real problems, review the most common errors before you practice again.

pH Mistakes

Why This Formula Matters

Titration is the standard technique in analytical chemistry for determining unknown concentrations. It is used in quality control to verify product purity, pharmaceutical testing to ensure correct drug dosages, environmental monitoring to measure pollutant levels, and food science to determine acidity.

Frequently Asked Questions

What is the Titration formula?

A lab technique for finding an unknown solution concentration by gradually adding a solution of known concentration until the reaction is complete.

How do you use the Titration formula?

Slowly adding a known solution to an unknown one until the reaction is just complete — the volume used reveals the concentration.

What do the symbols mean in the Titration formula?

M_A and M_B are the molarities (mol/L) of the analyte and titrant, V_A and V_B are their volumes, and the equivalence point is where n_A = n_B (moles are stoichiometrically equal).

Why is the Titration formula important in Chemistry?

Titration is the standard technique in analytical chemistry for determining unknown concentrations. It is used in quality control to verify product purity, pharmaceutical testing to ensure correct drug dosages, environmental monitoring to measure pollutant levels, and food science to determine acidity.

What do students get wrong about Titration?

The endpoint (indicator color change) may differ slightly from the equivalence point.

What should I learn before the Titration formula?

Before studying the Titration formula, you should understand: concentration, neutralization, mole.

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