Full Form of pH :
Potential of Hydrogen
pH Full Form is Potential of Hydrogen. pH is a unit of a numeric scale which is used to measure the base or acidic quantity of a substance. It is denoted as pH. The pH scale has a measure that ranges between 0 and 14 with 7 as the neutral or middle point. The chemical which has the pH value of less than 7 is said to be acidic. Similarly, a chemical that has pH value more than 7 is said to be basic (more alkaline). Water is said to have a pH value of 7.0, which is neutral. The letter ‘p’ refers to the German word ‘power’ or ‘potenz’. The letter H is the symbol for Hydrogen element. Here, ‘H’ is mentioned in the capital because it is a standard practice to refer to elements in capital letters. The pH scale is also called ‘logarithmic scale’. The pH concept was introduced in 1909 at Carlsberg Laboratory by a Danish chemist named Soren Peder Lauritz Sorensen.
pH Full Form – Additional Information
Potential of Hydrogen is a fundamental concept in chemistry, which is represented by the abridged form pH. It is essentially a numerical scale that is used for determining the alkalinity or acidity of a particular aqueous solution. It is negative of the logarithm to base 10 relating to the activity of the key hydrogen ions. Any aqueous solution which has a pH reading less than 7 is essentially acidic in nature whereas solutions with pH reading more than 7 are alkaline in nature.
Of all the solutions, pure water is one exception that is neutral, that is it is neither alkaline nor acidic in nature. In contrast to many beliefs, there are solutions with pH value even less than 0 and with reading more than 15, as in case of strong acids and alkaline respectively. pH is important in measuring several key characteristics of a particular aqueous solution and therefore, has been worked upon and improved a great deal. We have learned about it in our school chemistry classes but it is never enough because it is a very wide concept. So, here are five points about pH you must know:
History of pH
Søren Peder Lauritz Sørensen, a Danish chemist, introduced the concept of pH in the year 1909. He later modified the concept in the year 1924 when it became a modern pH concept. He did it by including measurements and definitions using terminology relating to electrochemical cells. The precise meaning of pH has invited a lot of disagreements among the scientific community. The Carlsberg Foundation states the word pH means Power of Hydrogen. Another view states that pH stands for Potential of Hydrogen. Perhaps, for the purpose of avoiding any confusion, the word pH is used as it is with barely any reference to its full meaning. What is settled that it determines the acidity or alkalinity of a solution.
Definition and measurement of pH
The definition of pH is in terms of the reciprocal form of the hydrogen ion’s, aH+, decimal logarithm in aqueous solution. The reason behind adopting this definition was primarily because the ion-selective electrode that is made use of in the measurement of pH value gives a response to the hydrogen ion activity. In an ideal situation, an electrode potential, which is denoted as E, observes the Nernst Equation. In a typical equation, E evaluates the potential and E0 is used as standard electrode potential; R denotes the gas constant; T denotes the Temperature in Kelvin; F denotes Faraday Constant.
The exact measurement of the pH value is presented as per International Standard, which is ISO 31-8. In the whole presentation, a galvanic cell is used for the purpose of measuring the electromotive force—denoted as e.m.f.—in between an electrode that is sensitive to the activity of hydrogen ion and a reference electrode and both are immersed in the same solution. A calomel electrode or a silver chloride electrode can very well be used as a reference electrode whereas the hydrogen ion selective electrode is a well established standard hydrogen electrode. A pH scale is basically logarithmic and it is for this reason, pH is a dimensionless value.
We have all worked with pH indicators in our school chemistry labs. SO, it must be known to almost everyone that indicators are often used for the purpose of measurement of the pH value of various aqueous solutions. The measurement is generally done on the basis of the color obtained on the indicators. The obtained color is then compared with a standard color chart which helps in arriving at the nearest accurate value. More precise evaluation can be attained when the color is evaluated spectrophotometrically, which is generally done by means of a spectrophotometer or a colorimeter.
The universal indicator comprises a mixture of various indicators, for example, there is a continual change in color from pH 2 to pH 10. A Universal indicator paper is made use of, which has absorbent characteristics. pOH is often used for the purpose of measuring the concentration of OH− ions, or in simpler terms, the alkalinity of the solution. When measurement of pH value below 2.5 and above 10.5 is to be done, special procedures are needed to be undertaken. In these procedures, a glass electrode is used and there is a breakdown of the Nernst equation. There are several factors that contribute to such breakdown.
Applications of pH
pH has applications in the following areas:
- The soil has a pH value, which varies with the kind of soil we are concerned with. The United States Department of Agriculture Natural Resources Conservation Service, which was previously known as Soil Conservation Service, has come with a classification of pH values for various soils.
- pH is found in many plant pigments, which are used in the form of pH indicators. Such pigments are found in red cabbage, hibiscus, and red wine. Citric fruits have high acidic content, as it composes of citric acid. The functional mechanism of hemoglobin is considerably affected by pH due to a process called the Root Effect.
- pH plays a key role in the maintenance of the carbon cycle in the ocean. pH is found in seawater within the range of 7.5.-8.4
- pH plays a key role in the human body, as it is found in blood, urine, human skin, pancreas secretions, gastric acid, lysosomes, etc.
pH scale is fundamental in measuring the chemical properties of a solution and it is extensively used in areas such as medicine, chemistry, biology, agriculture, agronomy, environmental science, chemical engineering, water treatment, nutrition, water purification, oceanography, food science, and forestry. There are set standards of solutions whose pH reading has been decided by international agreement. Concentration cell with transference is used for the determination of primary pH standard readings, which is done by calculating the potential difference between a standard electrode like the silver chloride electrode and a hydrogen electrode. The measurement of pH value of an aqueous solution can be evaluated with the help of a pH meter and a glass indicator
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