Titrant Definition in Chemistry

In analytical chemistry, the titrant is a solution of known concentration that is added (titrated) to another solution to determine the concentration of a second chemical species. The titrant may also be called the titrator, the reagent, or the standard solution.

In contrast, the analyte, or titrand, is the species of interest during a titration. When a known concentration and volume of titrant is reacted with the analyte, it's possible to determine the analyte concentration.

How It Works

The mole ratio between the reactants and products in a chemical equation is the key to using titration to determine an unknown concentration of a solution. Typically, a flask or beaker containing a precisely known volume of analyte, together with an indicator, is placed under a calibrated burette or pipette. The burette or pipette contains the titrant. You add the titrant dropwise until the indicator shows a color change, indicating the titration endpoint. Color change indicators are tricky, because the color may temporarily change before permanently changing. This introduces some degree of error into the calculation. When the endpoint is reached, the volume of reactant is determined using the equation:

C_a = C_tV_tM/V_a

Where C_a is the analyte concentration (usually given as molarity), C_t is titrant concentration (in the same units), V_t is the volume of titrant required to reach the endpoint (usually in liters), M is the mole ratio between the analyte and reactant from the balanced equation, and V_a is the analyte volume (usually in liters).