Titration Fundamentals
A titration can be used to determine the unknown concentration of a substance (the “analyte”) by slowly adding measured quantities of another substance (the “titrant”) which reacts with the analyte in a known proportion. There are several different types of titrations, including acid-base, redox, precipitation, and complex-formation. The titration endpoint can be signaled by an added color-changing substance, an electrical property of the solution, or a visible change to the titrant or analyte. The endpoint corresponds to or is very close to the “equivalence point,” the point at which all of the analyte and titrant have reacted, and the volume of titrant used to reach the endpoint can then be used to calculate the analyte concentration.
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Learning Objectives
Define the terms “titrant,” “analyte,” “standard solution,” “endpoint,” and “equivalence point”
Identify the variables of the titration equation, and demonstrate how to calculate an unknown concentration based on titration results
In an acid-base titration, select a color-changing indicator based on the equivalence point pH
Describe acid-base, redox, precipitation and complex-formation titrations
Describe potentiometric, conductometric, amperometric and coulometric titration methods
Identify when a back titration might be appropriate
Describe how the titration method is chosen
Specs
| Course Level | Intermediate |
| Languages | English |
| Compatibility | Audio, Video |
| Based on: | Industry Standards and Best Practices |
Key Questions
Why is it important to add the titrant solution in small quantities during a titration?
The titrant solution is added in small quantities because the endpoint occurs very quickly. If you add the titrant too quickly, you might miss the endpoint.
When can a precipitation titration be used?
Precipitation titrations can be used anytime the titrant and analyte react to form an insoluble substance that precipitates out of the solution.
In the calculation that is used to determine the concentration of the analyte solution, what is the “M”?
In the titration calculation, the “M” is the mole ratio of titrant to analyte in the governing chemical reaction. In other words, it accounts for the number of titrant molecules needed to react with each analyte molecule.
What is a redox titration?
In oxidation-reduction or “redox” titrations, electrons are transferred between the titrant and the analyte, which must be an oxidizing agent and a reducing agent.
What kind of titration can be used to determine the concentration of metal ions in a solution?
Complex-formation titrations use EDTA or another chelating agent as the titrant to form strong complexes with the metal ions and yield an easily identified endpoint.
Sample Video Transcript
If you were to plot pH versus the volume of added titrant, you would generate a pH titration curve. The equivalence point at which the acid and base have neutralized each other occurs at the midpoint of the steepest part of this curve. This is why the titrant is added slowly and in small quantities, in order to catch the steep part of the curve and not jump over it. A pH meter can be used to monitor the pH and identify the equivalence point or an indicator substance that exists in both acid and base forms, and changes color at or near the equivalence point pH can be used. When selecting an indicator, it is important to know the color change pHs of all available indicators.
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