Titration Formula

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

The Formula

n_A = n_B \implies M_A V_A = M_B V_B \quad (\text{for a 1:1 reaction; multiply by the mole ratio otherwise})

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}

Worked Examples

Example 1

medium

Worked example: pick the better indicator for a weak acid - strong base titration: methyl orange (pH 3-5) or phenolphthalein (pH 8-10)?

Answer

\text{Phenolphthalein}

First step

Weak acid + strong base equivalence pH > 7.

See the full worked solution + why-it-works coaching

SetupKey insightWhy it worksCommon pitfallConnection

Unlock answer keys One Family plan — every worked solution, all subjects

Example 2

medium

Worked example:

25.0\text{ mL}

0.100\text{ M}

HCl

is titrated with

0.100\text{ M}

NaOH

. How many mL of base have been added at the half-equivalence point?

Example 3

challenge

Worked example: a

1.000\text{ g}

aspirin tablet (

M = 180.2\text{ g/mol}

, monoprotic) requires

24.0\text{ mL}

0.200\text{ M}

NaOH

to reach equivalence. What percent by mass is aspirin?

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 - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement. - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement.
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 - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement. - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement.
Reading the burette incorrectly — the volume is read from the bottom of the meniscus, and parallax errors can lead to inaccurate results - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement. - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement.
Using titration from a keyword alone - Signal words like solution, solute, solvent only point to a possible model; the substances and evidence must match too. - Fix this by naming the substances or sample, checking "Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture?", and attaching units, formulas, states, or evidence to the final statement.

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 connects particle thinking to lab preparation. It is essential for titrations, dilution, solubility, electrolytes, and any reaction that happens in solution.

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 connects particle thinking to lab preparation. It is essential for titrations, dilution, solubility, electrolytes, and any reaction that happens in solution.

What do students get wrong about Titration?

Students often know a formula related to titration but skip the recognition step: Am I tracking solute, solvent, total solution, concentration, dissolving, or dilution rather than just naming a mixture? That leads to a correct-looking substitution attached to the wrong chemical model.

What should I learn before the Titration formula?

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

← Back to Titration See All Examples Common Mistakes Practice Problems

Related Concepts

Concentration Neutralization Mole pH

Related Formulas

Concentration Formula Mole Formula pH Formula