What Is "Direct Titration"?

By Chuck Robert; Updated April 24, 2017

Scientists rely on direct titration to find the quantity of a substance within a solution with chemical reactions. When performed correctly, this process can very accurately depict chemical quantities using specialized acids and laboratory glassware. For the titration to work properly, the last complex must form rapidly enough for the scientists to analyze it.

Definition

Direct titration is a way to determine the contents of a substance quantitatively. Scientists may be aware of a reactant, but not know the reactant’s quantity. Direct titration is sometimes based on indicators that respond to the analyzed material, called the analyte. Other times, the methods are based on the use of added metal ions, which are individual atoms or molecules of a specific type of metal.

Ethylenediaminetetracetic Acid and the Potentiometric Method

Technicians can perform titration using ethylenediaminetetracetic acid with metal-ion indicators. This method doesn’t work in all situations, since the reaction is sometimes so slow that titration becomes unrealistic. The used metal ion must have less stability than the analyte. Another method of direct titration is the potentiometric method, used for endpoint detection with metal ions that have specific available electrodes. The endpoint is the point where the titration process ends.

Complexometric Titration

For complexometric titration, scientists use aminopolycarboxylic acids to identify metals. Colored complexes form and the scientists use the data collected from this formation to determine the quantity of the analyte. The direct method of complexometric titration involves the use of a metal-salt solution titrated with a complexing compound solution. Complexing compound solutions contain atoms or compounds that form complexes with other atoms or compounds. Scientists find the equivalence point from an added indicator. The equivalence point is when the added titrant is stoichiometrically equal to the analyte. Stoichiometry involves chemical reactions balancing.

Burette Solution

Direct titration is called “direct” because the scientist approaches the endpoint directly. The titrant enters the solution through drops from the burette so the final drop does not surpass the endpoint. With direct titration, scientists treat a soluble substance contained in a solution, which is contained in a vessel called the titrate. The standardized solution is called the titrant. The endpoint is determined instrumentally or visually with the help of an indicator. Scientists add the titrant to the correct burette, a vertical and cylindrical piece of glassware with a precision tap that releases small amounts of liquid at specific amounts. The scientists fill the burette to 30 to 100 percent capacity.

About the Author

Chuck Robert specializes in nutrition, marketing, nonprofit organizations and travel. He has been writing since 2007, serving as a ghostwriter and contributing to online publications. Robert holds a Master of Arts with a dual specialization in literature and composition from Purdue University.