S.P.L. Sørensen Biography, PH Scale Founder, Google Doodle, Images
S.P.L. Sørensen Biography
The son of a farmer, Sørensen was educated at the high school at Sorø and entered the University of Copenhagen at the age of eighteen. He planned to study medicine; but under the influence of S. M. Jorgensen. An important investigator of inorganic complex compounds, he chose chemistry for his career. While at the university Sørensen received two gold medals. The first for a paper on the concept of the chemical radical and the second for a study of strontium compounds. While working for the doctorate he assisted in a geological survey of Denmark. Acted as assistant in chemistry at the laboratory of the Danish Polytechnic Institute. And served as a consultant at the royal naval dockyard. His doctoral dissertation (1899) concerned the chemistry of cobaltic oxides. Thus most of his training was in inorganic chemistry. S.P.L. Sørensen Biography
All this was changed when, in 1901. Sørensen succeeded Johann Kjeldahl as director of the chemical department of the Carlsberg Laboratory in Copenhagen. Where he remained for the rest of his life. Kjeldahl had worked on biochemical problems. And Sørensen continued this line of inquiry. His investigations can be divided into four classes: synthesis of amino acids, analytical studies, work on hydrogen ion concentration, and studies on proteins. The first, beginning in 1902, was concerned with synthesis of such amino acids as ornithine, proline, and arginine. The following year the demonstrated that the Kjeldahl method for determination of amino nitrogen was of much greater generality than its discoverer had claimed.After working out the Formal titration method for analysis of proteins, he turned to a study of the effects of such buffers as borates, citrates, phosphates, and glycine on the behavior of proteins, with especial attention to enzymes. S.P.L. Sørensen Biography
This work led Sørensen to study the at quinhydrone electrodes and the effect of ion concentration in the analysis of proteins. His most notable suggestion came from this work. In 1909 he investigated the EMF method for determining hydrogen ion concentration. And introduced concept of pH as an easy and convenient for expressing this value. He was particularly interested in the effects of changes in pH on precipitation of proteins. After 1910 Sørensen made many studies on the application of thermodynamics to proteins. And the quantitative characterization of these substances in terms of laws and constants. In much of this work he was assisted by his wife, Margrethe Høyrup Sørensen. They studied lipoproteins and the complexes of carbon monoxide with hemoglobin. And in 1917 succeeded crystallizing egg albumin for the first time. S.P.L. Sørensen Biography
Sørensen always encouraged visiting scientists at the Carlsberg Laboratory to work on medical problems. He also was active in chemical technology, contributing to the Danish spirits, yeast, and explosive industries. He received many honors from both scientific and technological societies. Sørensen retired in 1938 after a period of poor health and died the following year. S.P.L. Sørensen Biography
Sören Peter Lauritz Sörensen (sö´rən pē´tər lou´rēts sö´rənsən), 1868–1939, Danish biochemist. In 1899 he received a Ph.D. degree in Copenhagen. Sörensen was director of chemistry at Carlsberg Laboratory and worked as a professor in Copenhagen. His work on hydrogen ion concentration led him to suggest that it be measured in a unit he called pH. Numerical values based on this unit, now universally in use, give an indication of the acidity of solutions. He also did pioneering research on amino acid synthesis and on the nature of enzyme reactions.
S.P.L. Sørensen PH
The measurement was originally used by the Danish biochemist S.P.L. Sørensen to represent the hydrogen ion concentration. Expressed in equivalents per litre, of an aqueous solution: pH = −log[H+] (in expressions of this kind, enclosure of a chemical symbol within square brackets denotes that the concentration of the symbolized species is the quantity being considered). S.P.L. Sørensen Biography
Because of uncertainty about the physical significance of the hydrogen ion concentration. The definition of the pH is an operational one; i.e., it is based on a method of measurement. The U.S. National Bureau of Standards has defined pH values in terms of the electromotive force existing between certain standard electrodes in specified solutions.
The pH is usually measured with a pH meter, which translates into pH readings the difference in electromotive force (electrical potential or voltage) between suitable electrodes placed in the solution to be tested. Fundamentally, a pH meter consists of a voltmeter attached to a pH-responsive electrode and a reference (unvarying) electrode. The pH-responsive electrode is usually glass. And the reference is usually a mercury-mercurous chloride (calomel) electrode, although a silver-silver chloride electrode is sometimes used. S.P.L. Sørensen Biography
When the two electrodes are immersed in a solution, they act as a battery. The glass electrode develops an electric potential (charge) that is directly related to the hydrogen-ion activity in the solution. And the voltmeter measures the potential difference between the glass and reference electrodes. The meter may have either a digital or an analog (scale and deflected needle) readout.
Great Discovery of ph
Digital readouts have the advantage of exactness, while analog readouts give better indications of rates of change. Battery-powered portable pH meters are widely used for field tests of the pH of soils. Tests of pH may also be performed, less accurately, with litmus paper or by mixing indicator dyes in liquid suspensions and matching the resulting colours against a colour chart calibrated in pH. S.P.L. Sørensen Biography
In agriculture, the pH is probably the most important single property of the moisture associated with a soil. Since that indication reveals what crops will grow readily in the soil. And what adjustments must be made to adapt it for growing any other crops. Acidic soils are often considered infertile. And so they are for most conventional agricultural crops, although conifers and many members of the family Ericaceae, such as blueberries, will not thrive in alkaline soil.
Acidic soil can be “sweetened,” or neutralized, by treating it with lime. As soil acidity increases so does the solubility of aluminum and manganese in the soil. And many plants (including agricultural crops) will tolerate only slight quantities of those metals. Acid content of soil is heightened by the decomposition of organic material by microbial action. By fertilizer salts that hydrolyze or nitrify, by oxidation of sulfur compounds when salt marshes are drained for use as farmland, and by other causes. S.P.L. Sørensen Biography
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