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The pH after the equivalence point depends on the concentration of the conjugate base of the weak acid and the strong base of the titrant. However, the base of the titrant is stronger than the conjugate base of the acid. Therefore, the pH in this region is controlled by the strong base. As such the pH can be found using the following: [1]
In chemistry, an acid–base reaction is a chemical reaction that occurs between an acid and a base.It can be used to determine pH via titration.Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their application in solving related problems; these are called the acid–base theories, for example, Brønsted–Lowry acid–base theory.
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. [1] Hence, a pH indicator is a chemical detector for hydronium ions (H 3 O +) or hydrogen ions (H +) in the ...
A typical titration curve of a diprotic acid, oxalic acid, titrated with a strong base, sodium hydroxide.Both equivalence points are visible. Titrations are often recorded on graphs called titration curves, which generally contain the volume of the titrant as the independent variable and the pH of the solution as the dependent variable (because it changes depending on the composition of the ...
The isohydric principle is the phenomenon whereby multiple acid/base pairs in solution will be in equilibrium with one another, tied together by their common reagent: the hydrogen ion and hence, the pH of solution. That is, when several buffers are present together in the same solution, they are all exposed to the same hydrogen ion activity.
Therefore, a buffer solution may be added to the titration chamber to maintain the pH. [20] In instances where two reactants in a sample may react with the titrant and only one is the desired analyte, a separate masking solution may be added to the reaction chamber which eliminates the effect of the unwanted ion. [21]
In a titration of a weak acid with a strong base the pH rises more steeply as the end-point is approached. At the end-point, the slope of the curve of pH with respect to amount of titrant is a maximum. Since the end-point occurs at pH greater than 7, the most suitable indicator to use is one, like phenolphthalein, that changes color at high pH. [2]
When there is a hydrogen ion gradient between two sides of the biological membrane, the concentration of some weak bases are focused on only one side of the membrane. [6] Weak bases tend to build up in acidic fluids. [6] Acid gastric contains a higher concentration of weak base than plasma. [6]