PH

pH levelneutralpH valuepH levelsaciditypH rangealkalineblood pHocean aciditypH scale
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is.wikipedia
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Logarithmic scale

logarithmiclogarithmic unitLog
The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution (a lower pH indicates a higher concentration of hydrogen ions).
Common uses include earthquake strength, sound loudness, light intensity, and pH of solutions.

Glass electrode

pH glass electrodeminiature pH electrodepH-electrode
The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or a color-changing indicator.
The most common application of ion-selective glass electrodes is for the measurement of pH.

PH indicator

indicatorindicatorschemical indicator
The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or a color-changing indicator. pH-dependent plant pigments that can be used as pH indicators occur in many plants, including hibiscus, red cabbage (anthocyanin) and red wine.
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.

PH meter

pH electrodepH-metermeter
The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or a color-changing indicator.
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.

Aqueous solution

aqueouswater solubilityaqueous solutions
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is.
Aqueous solution is water with a pH of 7.0 where the hydrogen ions (H + ) and hydroxide ions (OH − ) are in Arrhenius balance (10 −7 ).

Acid dissociation constant

p''K'' a pKapK a
Currently in chemistry, the p stands for "decimal cologarithm of", and is also used in the term pK a, used for acid dissociation constants and pOH, the equivalent for hydroxide ions.
In particular, the pH of a solution can be predicted when the analytical concentration and pK a values of all acids and bases are known; conversely, it is possible to calculate the equilibrium concentration of the acids and bases in solution when the pH is known.

Thermodynamic activity

activityactivitieschemical activity
More precisely, pH is the negative of the base 10 logarithm of the activity of the hydrogen ion. pH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, a H +, in a solution.
For example, pH is defined as the negative logarithm of the hydrogen ion activity.

Chemistry

chemistchemicalApplied Chemistry
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is. Currently in chemistry, the p stands for "decimal cologarithm of", and is also used in the term pK a, used for acid dissociation constants and pOH, the equivalent for hydroxide ions.
One measurement, based on the Arrhenius definition of acidity, is pH, which is a measurement of the hydronium ion concentration in a solution, as expressed on a negative logarithmic scale.

Logarithm

logarithmsloglogarithmic function
pH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, a H +, in a solution.
In chemistry, pH is a logarithmic measure for the acidity of an aqueous solution.

S. P. L. Sørensen

Søren Peder Lauritz SørensenS.P.L. SørensenPeter Lauritz Sørensen
The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells.
Søren Peter Lauritz Sørensen (9 January 1868 – 12 February 1939) was a Danish chemist, famous for the introduction of the concept of pH, a scale for measuring acidity and alkalinity.

Buffer solution

bufferbufferedbuffers
It is calibrated against buffer solutions of known hydrogen ion activity.
A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa.

Hydroxide

OHhydroxide ionOH −
Currently in chemistry, the p stands for "decimal cologarithm of", and is also used in the term pK a, used for acid dissociation constants and pOH, the equivalent for hydroxide ions.
The pH of a solution is equal to the decimal cologarithm of the hydrogen cation concentration; the pH of pure water is close to 7 at ambient temperatures.

Food safety

food hygienesafetyfood inspection
Bacteriologist Alice C. Evans, famed for her work's influence on dairying and food safety, credited William Mansfield Clark and colleagues (of whom she was one) with developing pH measuring methods in the 1910s, which had a wide influence on laboratory and industrial use thereafter.
If an environment is high in starch or protein, water, oxygen, has a neutral PH level, and maintains a temperature between 5ºC and 60ºC (danger zone) for even a brief period of time (~0-20 minutes), bacteria are likely to survive.

Carlsberg Laboratory

CarlsbergCarlsberg Chemical LaboratoriumCarlsberg laboratories
The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells.
The Carlsberg Laboratory was known for isolating Saccharomyces carlsbergensis, the species of yeast responsible for lager fermentation, as well as for introducing the concept of pH in acid-base chemistry.

Arnold Orville Beckman

Arnold O. BeckmanArnold BeckmanArnold and Mabel Beckman
The first electronic method for measuring pH was invented by Arnold Orville Beckman, a professor at California Institute of Technology in 1934.
Sunkist needed to know the acidity of the product at any given time, and the colorimetric methods then in use, such as readings from litmus paper, did not work well because sulfur dioxide interfered with them.

Titration

titranttitratetitrated
One way to do this, which has been used extensively, is to titrate a solution of known concentration of a strong acid with a solution of known concentration of strong alkaline in the presence of a relatively high concentration of background electrolyte.
Many non-acid–base titrations require a constant pH during the reaction.

Acid

acidicacidityacids
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is.
An aqueous solution of an acid has a pH less than 7 and is colloquially also referred to as 'acid' (as in 'dissolved in acid'), while the strict definition refers only to the solute.

Agronomy

agronomistarableagronomic
Measurements of pH are important in chemistry, agronomy, medicine, water treatment, and many other applications.
The percentage of organic matter, soil pH, and nutrient holding capacity (cation exchange capacity) are tested in a regional laboratory.

Acidity function

pH is an example of an acidity function.
The pH scale is by far the most commonly used acidity function, and is ideal for dilute aqueous solutions.

Anthocyanin

anthocyaninsanthocyanin biosynthesisE163
pH-dependent plant pigments that can be used as pH indicators occur in many plants, including hibiscus, red cabbage (anthocyanin) and red wine.
Anthocyanins (also anthocyans; from Greek: ἄνθος (anthos) "flower" and κυάνεος/κυανοῦς kyaneos/kyanous "dark blue") are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue or black.

Bicarbonate

hydrogen carbonateHCO 3 HCO 3 −
This is because water absorbs carbon dioxide from the air, which is then slowly converted into bicarbonate and hydrogen ions (essentially creating carbonic acid).
Bicarbonate serves a crucial biochemical role in the physiological pH buffering system.

Gran plot

The calibration is usually carried out using a Gran plot.
Gran plots use linear approximations of the a priori non-linear relationships between the measured quantity, pH or electromotive potential (emf), and the titrant volume.

Universal indicator

The name
Universal indicator consists of a mixture of indicators such that there is a continuous color change from about pH 2 to pH 10.
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions.

Hammett acidity function

H 0 H'' 0
For example, the Hammett acidity function, H 0, has been developed in connection with superacids.
It was proposed by the physical organic chemist Louis Plack Hammett and is the best-known acidity function used to extend the measure of Brønsted–Lowry acidity beyond the dilute aqueous solutions for which the pH scale is useful.

Alkali

alkalinealkalisalkalinity
When a base, or alkali, is dissolved in water, the pH will be greater than 7.
A solution of a soluble base has a pH greater than 7.0.