At the end of this module, you will be able to:
- 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
The following key questions are answered in this module:
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.
Below is a transcript of the video sample provided for this module:
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.
Use the additional resources and links below to learn more about this topic: