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The pH scale is logarithmic and therefore pH is a dimensionless quantity. p[H] This was the original definition of Sørensen in 1909, which was superseded in favor of pH in 1924. [H] is the concentration of hydrogen ions, denoted [H +] in modern chemistry.
The Henderson–Hasselbalch equation can be used to estimate the pH of a buffer solution by approximating the actual concentration ratio as the ratio of the analytical concentrations of the acid and of a salt, MA. The equation can also be applied to bases by specifying the protonated form of the base as the acid. For example, with an amine,
The form pK a is often used because it provides a convenient logarithmic scale, where a lower pK a corresponds to a stronger acid. Theoretical background [ edit ] The acid dissociation constant for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the p K a value is directly proportional to the ...
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 base-10 log scale is used for the Y axis of the bottom left graph, and the Y axis ranges from 0.1 to 1,000. The top right graph uses a log-10 scale for just the X axis, and the bottom right graph uses a log-10 scale for both the X axis and the Y axis. Presentation of data on a logarithmic scale can be helpful when the data:
Weak. v. t. e. An acidity function is a measure of the acidity of a medium or solvent system, [1] [2] usually expressed in terms of its ability to donate protons to (or accept protons from) a solute ( Brønsted acidity ). The pH scale is by far the most commonly used acidity function, and is ideal for dilute aqueous solutions.
Log scales and variants are commonly used, for instance, for the volcanic explosivity index, the Richter scale for earthquakes, the magnitude of stars, and the pH of acidic and alkaline solutions. Even in these cases, the log scale can make the data less apparent to the eye.
The partition coefficient, abbreviated P, is defined as a particular ratio of the concentrations of a solute between the two solvents (a biphase of liquid phases), specifically for un- ionized solutes, and the logarithm of the ratio is thus log P. [10] : 275ff When one of the solvents is water and the other is a non-polar solvent, then the log ...