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Different methods to determine the equivalence point include: pH indicator A pH indicator is a substance that changes color in response to a chemical change. An acid-base indicator (e.g., phenolphthalein) changes color depending on the pH. Redox indicators are also frequently used. A drop of indicator solution is added to the titration at 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 isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). [1] However, pI is also used. [2] For brevity, this article uses pI.
A Gran plot (also known as Gran titration or the Gran method) is a common means of standardizing a titrate or titrant by estimating the equivalence volume or end point in a strong acid-strong base titration or in a potentiometric titration.
The equivalence point occurs between pH 8-10, indicating the solution is basic at the equivalence point and an indicator such as phenolphthalein would be appropriate. Titration curves corresponding to weak bases and strong acids are similarly behaved, with the solution being acidic at the equivalence point and indicators such as methyl orange ...
The pH at the end-point or equivalence point in a titration may be calculated as follows. At the end-point the acid is completely neutralized so the analytical hydrogen ion concentration, T H, is zero and the concentration of the conjugate base, A −, is equal to the analytical or formal concentration T A of the acid: [A −] = T A.
In acid-base titrations, an unfitting pH indicator may induce a color change in the indicator-containing solution before or after the actual equivalence point. As a result, different equivalence points for a solution can be concluded based on the pH indicator used. This is because the slightest color change of the indicator-containing solution ...
pH after the equivalence point; 1. The initial pH is approximated for a weak acid solution in water using the equation: [1] = [+] where [+] is the initial concentration of the hydronium ion. 2. The pH before the equivalence point depends on the amount of weak acid remaining and the amount of conjugate base formed.