Investigating Acid-Base Titrations
Experiment #14 from Vernier Chemistry Investigations for Use with AP* Chemistry
- Education Level
- High School
- Subject
- Chemistry
Introduction
A titration is a laboratory process used to determine the volume of a solution needed to react with a given amount of another solution. One of the most common titrations performed in a Chemistry lab is an acid-base titration. In the Initial Investigation, you will be assigned an acid solution to titrate with a solution of the strong base sodium hydroxide, NaOH. The concentration of the NaOH solution is given and you will determine the concentration of the acid solution.
Your assigned acid may be strong, such as hydrochloric acid, HCl, or weak, such as acetic acid, CH3COOH. When titrating a strong acid, the main objective is to determine the equivalence point of the titration. Near the equivalence point, the pH increases very rapidly. The graph of a strong acid-strong base titration is analyzed as accurately as possible to determine the exact amount of NaOH needed to neutralize all the acid.
In the case of titrating a weak acid, a second objective is to determine an equilibrium constant. In reacting with a base, a weak acid will establish an equilibrium that can be evaluated mathematically, and is abbreviated as Ka. A Ka value is a unique quantity, which helps identify the acid. A weak acid may also have more than one Ka, depending on how many dissociation steps it undergoes in releasing ionizable hydrogen to form H3O+ ions.
After completing the Initial Investigation, you will be given a weak acid solution of unknown identity and concentration to test by titration. It will be helpful to use reference sources to find out more about acids and bases, acid-base titrations, and weak acid equilibria before planning and conducting your investigation.
Objectives
You will be assigned an acid solution to titrate with a solution of the strong base sodium hydroxide, NaOH. The concentration of the NaOH solution is given and you will determine the concentration of the acid solution.
Sensors and Equipment
This experiment features the following sensors and equipment. Additional equipment may be required.
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This experiment is #14 of Vernier Chemistry Investigations for Use with AP* Chemistry. The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.
