Titration
Definition and meaning of Titration in chemistry.
Titration is a common lab technique used to find the exact concentration of a chemical. You slowly add a liquid with a known concentration into a liquid with an unknown concentration. You stop adding liquid exactly when the two chemicals finish reacting.
In more detail
Chemists use a tall glass tube called a buret for this chemical process. The buret lets them measure exactly how many drops of liquid they add. They drip the known chemical into a flask containing the unknown chemical.
The flask also holds a few drops of a special color-changing dye. This special testing dye is scientifically known in the lab as an indicator. The indicator changes color the exact moment the main chemical reaction finishes.
Chemists refer to this sudden color change as the endpoint of the titration. The real mathematical goal of the experiment is to hit the equivalence point. This theoretical point happens when the added molecules perfectly match the unknown molecules.
A good indicator changes color at almost the exact same time as the equivalence point. You can then use the final volume on the buret to calculate your answer. A common student mistake is reading the buret volume numbers upside down. Burets have the zero mark at the very top instead of the bottom.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Main Apparatus | Buret and Erlenmeyer flask |
| Titrant | The liquid with a known concentration |
| Analyte | The liquid with an unknown concentration |
| Equivalence point | When moles of added chemical perfectly match unknown chemical |
Imagine you have a flask of hydrochloric acid with an unknown strength. You fill a buret with a basic sodium hydroxide solution of exactly 0.10 M. You add a pink indicator dye to the acid in your glass flask. You slowly drip the base into the acid until the liquid turns permanently pink. You check the buret and see you used exactly 20.0 milliliters of base. You can now use simple stoichiometry math to find the exact acid concentration.
Frequently asked questions
What is the difference between the equivalence point and the endpoint?
The equivalence point is the invisible moment when the chemicals perfectly balance each other. The endpoint is the visible moment when the indicator dye changes color.
Why must you read the buret at eye level?
Water curves down in a glass tube to form a shape called a meniscus. Reading from an angle gives you the wrong volume number.
Can you do a titration without a color indicator?
Yes, you can use a digital pH meter instead of a color dye. The meter tracks the acid levels and creates a graph to show the equivalence point.