Titration Procedure & Endpoint Detection Cheat Sheet

Key Facts

• Molarity is calculated with $M = \frac{n}{V}$, where $M$ is molarity, $n$ is moles, and $V$ is volume in liters.
• The moles of solute can be found from $n = MV$ when the solution molarity and volume are known.
• For a reaction $aA + bB \rightarrow cC + dD$, mole ratios come from the coefficients, so $\frac{n_A}{a} = \frac{n_B}{b}$ at equivalence.
• For a simple $1:1$ acid-base titration, the relationship at equivalence is $M_{acid}V_{acid} = M_{base}V_{base}$.
• All titration volumes used in calculations must be converted to liters using $1\text{ L} = 1000\text{ mL}$.
• The endpoint is the observed indicator change, such as a faint pink color that lasts about $30\text{ s}$ with phenolphthalein.
• The equivalence point is reached when stoichiometric amounts of acid and base have reacted exactly according to the balanced equation.
• Percent error is calculated with $\%\text{ error} = \left|\frac{\text{experimental} - \text{accepted}}{\text{accepted}}\right| \times 100\%$.

Vocabulary

Titration

A method for determining an unknown concentration by reacting a measured sample with a solution of known concentration.

Titrant

The solution of known concentration added from the buret during a titration.

Analyte

The solution being tested, usually placed in the flask, whose concentration is unknown.

Endpoint

The visible change, often a color change, that signals the titration should stop.

Equivalence Point

The point where the reactants have combined in the exact mole ratio shown by the balanced equation.

Indicator

A substance that changes color over a certain pH range to help show when the endpoint is reached.