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  2. pH - Wikipedia

    en.wikipedia.org/wiki/PH

    The measurement of pH can become difficult at extremely acidic or alkaline conditions, such as below pH 2.5 (ca. 0.003 mol/dm 3 acid) or above pH 10.5 (above ca. 0.0003 mol/dm 3 alkaline). This is due to the breakdown of the Nernst equation in such conditions when using a glass electrode.

  3. pH meter - Wikipedia

    en.wikipedia.org/wiki/PH_meter

    Beckman Model M pH Meter, 1937 [1] Beckman model 72 pH meter, 1960 781 pH/Ion Meter pH meter by Metrohm. A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. [2]

  4. pH indicator - Wikipedia

    en.wikipedia.org/wiki/PH_indicator

    pH measurement with indicator paper. pH indicators are frequently employed in titrations in analytical chemistry and biology to determine the extent of a chemical reaction. [1] Because of the subjective choice (determination) of color, pH indicators are susceptible to imprecise readings. For applications requiring precise measurement of pH, a ...

  5. Glass electrode - Wikipedia

    en.wikipedia.org/wiki/Glass_electrode

    The most common application of ion-selective glass electrodes is for the measurement of pH. The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions. Glass electrodes play an important part in the instrumentation for chemical analysis, and physicochemical studies.

  6. Acidity function - Wikipedia

    en.wikipedia.org/wiki/Acidity_function

    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.

  7. Universal indicator - Wikipedia

    en.wikipedia.org/wiki/Universal_indicator

    A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. A universal indicator can be in paper form or present in a form of a solution. [1]

  8. Soil pH - Wikipedia

    en.wikipedia.org/wiki/Soil_pH

    Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics.

  9. Acid value - Wikipedia

    en.wikipedia.org/wiki/Acid_value

    In chemistry, acid value (AV, acid number, neutralization number or acidity) is a number used to quantify the acidity of a given chemical substance.It is the quantity of base (usually potassium hydroxide (KOH)), expressed as milligrams of KOH required to neutralize the acidic constituents in 1 gram of a sample.