Hydroelectricity, or hydroelectric power, is electricity produced from hydropower. In 2015, hydropower generated 16.6% of the world's total electricity and 70% of all renewable electricity,[2] and was expected to increase by about 3.1% each year for the next 25 years.
Hydropower is produced in 150 countries, with the Asia-Pacific region generating 33 percent of global hydropower in 2013. China is the largest hydroelectricity producer, with 920 TWh of production in 2013, representing 16.9% of domestic electricity use.
The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. The hydro station consumes no water, unlike coal or gas plants. The typical cost of electricity from a hydro station larger than 10 megawatts is 3 to 5 US cents per kilowatt hour.[3] With a dam and reservoir it is also a flexible source of electricity, since the amount produced by the station can be varied up or down very rapidly (as little as a few seconds) to adapt to changing energy demands. Once a hydroelectric complex is constructed, the project produces no direct waste, and it generally has a considerably lower output level of greenhouse gases than photovoltaic power plants and certainly fossil fuel powered energy plants (see also Life-cycle greenhouse-gas emissions of energy sources).[4] However, when constructed in lowland rainforest areas, where inundation of a part of the forest is necessary, they can emit substantial amounts of greenhouse gases.
The construction of a hydroelectric complex can cause significant environmental impact, principally in loss of arable land and population displacement. They also disrupt the natural ecology of the river involved, affecting habitats and ecosystems, and the siltation and erosion patterns. While dams can ameliorate the risks of flooding, they also contain a risk of dam failure, which can be catastrophic.
https://en.wikipedia.org/wiki/Hydroelectricity
All of the researchers noted Cavendish's production of pure water by burning hydrogen in oxygen, but they interpreted the reaction in varying ways within the framework of phlogiston theory. Lavoisier learned of Cavendish's experiment in June 1783 via Charles Blagden (before the results were published in 1784), and immediately recognized water as the oxide of a hydroelectric gas.[42]
https://en.wikipedia.org/wiki/Antoine_Lavoisier
Joseph Black's "fixed air"
Oxygen theory of combustion
Sir Charles Brian Blagden FRS (17 April 1748 – 26 March 1820)[1] was a British physician and scientist.[2] He served as a medical officer in the Army (1776–1780) and later held the position of Secretary of the Royal Society (1784–1797). Blagden won the Copley Medal in 1788 and was knighted in 1792.
He died in Arcueil, France in 1820, and was buried at Père Lachaise Cemetery in Paris.[1]
Born17 April 1748
Died26 March 1820 (aged 71)
NationalityUnited KingdomKnown forStudies of perspiration and the freezing point of solutionsAwardsCopley Medal (1788)
https://en.wikipedia.org/wiki/Charles_Blagden
The same year he coined the name oxygen for this constituent of the air, from the Greek words meaning "acid former".[35][41] He was struck by the fact that the combustion products of such nonmetals as sulfur, phosphorus, charcoal, and nitrogen were acidic. He held that all acids contained oxygen and that oxygen was therefore the acidifying principle.
Dismantling phlogiston theory
Lavoisier's chemical research between 1772 and 1778 was largely concerned with developing his own new theory of combustion. In 1783 he read to the academy his paper entitled Réflexions sur le phlogistique (Reflections on Phlogiston), to consider a proposal to explanation of phenomena (that should provide an alternative to the popular contemporary phlogiston theory of combustion). That year Lavoisier also began a series of experiments on the composition of water which were to prove an important capstone to his combustion theory and win many converts to it. Many investigators had been experimenting with the combination of Henry Cavendish's inflammable air, which Lavoisier termed hydrogen (Greek for "water-former"), with "dephlogisticated air" (air in the process of combustion, now known to be oxygen) by electrically sparking mixtures of the gases. All of the researchers noted Cavendish's production of pure water by burning hydrogen in oxygen, but they interpreted the reaction in varying ways within the framework of phlogiston theory. Lavoisier learned of Cavendish's experiment in June 1783 via Charles Blagden (before the results were published in 1784), and immediately recognized water as the oxide of a hydroelectric gas.[42]
In cooperation with Laplace, Lavoisier synthesized water by burning jets of hydrogen and oxygen in a bell jar over mercury. The quantitative results were good enough to support the contention that water was not an element, as had been thought for over 2,000 years, but a compound of two gases, hydrogen and oxygen. The interpretation of water as a compound explained the inflammable air generated from dissolving metals in acids (hydrogen produced when water decomposes) and the reduction of calces by inflammable air (a combination of gas from calx with oxygen to form water).[39]
Despite these experiments, Lavoisier's antiphlogistic approach remained unaccepted by many other chemists. Lavoisier labored to provide definitive proof of the composition of water, attempting to use this in support of his theory. Working with Jean-Baptiste Meusnier, Lavoisier passed water through a red-hot iron gun barrel, allowing the oxygen to form an oxide with the iron and the hydrogen to emerge from the end of the pipe. He submitted his findings of the composition of water to the Académie des Sciences in April 1784, reporting his figures to eight decimal places.[39] Opposition responded to this further experimentation by stating that Lavoisier continued to draw the incorrect conclusions and that his experiment demonstrated the displacement of phlogiston from iron by the combination of water with the metal. Lavoisier developed a new apparatus which utilized a pneumatic trough, a set of balances, a thermometer, and a barometer, all calibrated carefully. Thirty savants were invited to witness the decomposition and synthesis of water using this apparatus, convincing many who attended of the correctness of Lavoisier's theories. This demonstration established water as a compound of oxygen and hydrogen with great certainty for those who viewed it. The dissemination of the experiment, however, proved subpar, as it lacked the details to properly display the amount of precision taken in the measurements. The paper ended with a hasty statement that the experiment was "more than sufficient to lay hold of the certainty of the proposition" of the composition of water and stated that the methods used in the experiment would unite chemistry with the other physical sciences and advance discoveries.[43]
https://en.wikipedia.org/wiki/Antoine_Lavoisier
https://en.wikipedia.org/wiki/James_Keir
https://en.wikipedia.org/wiki/William_Nicholson_(chemist)
https://en.wikipedia.org/wiki/Ammonia
https://en.wikipedia.org/wiki/Sodium_oxide
https://en.wikipedia.org/wiki/Jean-Baptiste_Biot
https://en.wikipedia.org/wiki/Potash
https://en.wikipedia.org/wiki/Strontium_oxide
https://en.wikipedia.org/wiki/Barium_oxide
https://en.wikipedia.org/wiki/Magnesium_oxide
https://en.wikipedia.org/wiki/Jean_Baptiste_Meusnier
https://en.wikipedia.org/wiki/Chemical_affinity
https://en.wikipedia.org/wiki/Ferrocerium
https://en.wikipedia.org/wiki/Friedlieb_Ferdinand_Runge
https://en.wikipedia.org/wiki/Jean-Baptiste_Biot
https://en.wikipedia.org/wiki/Joseph_Louis_Gay-Lussac
Reactions[edit]
Elemental strontium is formed when strontium oxide is heated with aluminium in a vacuum (pressure).[1]
https://en.wikipedia.org/wiki/Strontium_oxide
https://en.wikipedia.org/wiki/Calorimetry
https://en.wikipedia.org/wiki/Acid–base_reaction
https://en.wikipedia.org/wiki/Gas_holder
https://en.wikipedia.org/wiki/Redox
https://en.wikipedia.org/wiki/Stoichiometry
https://en.wikipedia.org/wiki/Thermochemistry
A vacuum is a space devoid of matter. The word is derived from the Latin adjective vacuus for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure.[1] Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure.[2] The Latin term in vacuo is used to describe an object that is surrounded by a vacuum.
The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%.[3] But higher-quality vacuums are possible. Ultra-high vacuumchambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm3.[4] Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average in intergalactic space.[5]
Vacuum has been a frequent topic of philosophical debate since ancient Greek times, but was not studied empirically until the 17th century. Evangelista Torricelliproduced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A Torricellian vacuum is created by filling a tall glass container closed at one end with mercury, and then inverting it in a bowl to contain the mercury (see below).[6]
Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technologies has since become available. The development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general.
https://en.wikipedia.org/wiki/Vacuum
Oxygen theory of combustion
During late 1772 Lavoisier turned his attention to the phenomenon of combustion, the topic on which he was to make his most significant contribution to science. He reported the results of his first experiments on combustion in a note to the Academy on 20 October, in which he reported that when phosphorus burned, it combined with a large quantity of air to produce acid spirit of phosphorus, and that the phosphorus increased in weight on burning. In a second sealed note deposited with the Academy a few weeks later (1 November) Lavoisier extended his observations and conclusions to the burning of sulfur and went on to add that "what is observed in the combustion of sulfur and phosphorus may well take place in the case of all substances that gain in weight by combustion and calcination: and I am persuaded that the increase in weight of metallic calces is due to the same cause."
Joseph Black's "fixed air"
During 1773 Lavoisier determined to review thoroughly the literature on air, particularly "fixed air," and to repeat many of the experiments of other workers in the field. He published an account of this review in 1774 in a book entitled Opuscules physiques et chimiques (Physical and Chemical Essays). In the course of this review, he made his first full study of the work of Joseph Black, the Scottish chemist who had carried out a series of classic quantitative experiments on the mild and caustic alkalies. Black had shown that the difference between a mild alkali, for example, chalk (CaCO3), and the caustic form, for example, quicklime (CaO), lay in the fact that the former contained "fixed air," not common air fixed in the chalk, but a distinct chemical species, now understood to be carbon dioxide (CO2), which was a constituent of the atmosphere. Lavoisier recognized that Black's fixed air was identical with the air evolved when metal calces were reduced with charcoal and even suggested that the air which combined with metals on calcination and increased the weight might be Black's fixed air, that is, CO2.
Joseph Priestley
In the spring of 1774, Lavoisier carried out experiments on the calcination of tin and lead in sealed vessels, the results of which conclusively confirmed that the increase in weight of metals in combustion was due to combination with air. But the question remained about whether it was in combination with common atmospheric air or with only a part of atmospheric air. In October the English chemist Joseph Priestley visited Paris, where he met Lavoisier and told him of the air which he had produced by heating the red calx of mercury with a burning glass and which had supported combustion with extreme vigor. Priestley at this time was unsure of the nature of this gas, but he felt that it was an especially pure form of common air. Lavoisier carried out his own researches on this peculiar substance. The result was his memoir On the Nature of the Principle Which Combines with Metals during Their Calcination and Increases Their Weight, read to the Academy on 26 April 1775 (commonly referred to as the Easter Memoir). In the original memoir Lavoisier showed that the mercury calx was a true metallic calx in that it could be reduced with charcoal, giving off Black's fixed air in the process.[35] When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air and that it was the air itself "undivided, without alteration, without decomposition" which combined with metals on calcination.
After returning from Paris, Priestley took up once again his investigation of the air from mercury calx. His results now showed that this air was not just an especially pure form of common air but was "five or six times better than common air, for the purpose of respiration, inflammation, and ... every other use of common air". He called the air dephlogisticated air, as he thought it was common air deprived of its phlogiston. Since it was therefore in a state to absorb a much greater quantity of phlogiston given off by burning bodies and respiring animals, the greatly enhanced combustion of substances and the greater ease of breathing in this air were explained.
Pioneer of stoichiometry
Lavoisier's researches included some of the first truly quantitative chemical experiments. He carefully weighed the reactants and products of a chemical reaction in a sealed glass vessel so that no gases could escape, which was a crucial step in the advancement of chemistry.[36] In 1774, he showed that, although matter can change its state in a chemical reaction, the total mass of matter is the same at the end as at the beginning of every chemical change. Thus, for instance, if a piece of wood is burned to ashes, the total mass remains unchanged if gaseous reactants and products are included. Lavoisier's experiments supported the law of conservation of mass. In France it is taught as Lavoisier's Law and is paraphrased from a statement in his Traité Élémentaire de Chimie: "Nothing is lost, nothing is created, everything is transformed." Mikhail Lomonosov (1711–1765) had previously expressed similar ideas in 1748 and proved them in experiments; others whose ideas pre-date the work of Lavoisier include Jean Rey (1583–1645), Joseph Black (1728–1799), and Henry Cavendish (1731–1810).[37]
Chemical nomenclature
Lavoisier, together with Louis-Bernard Guyton de Morveau, Claude-Louis Berthollet, and Antoine François de Fourcroy, submitted a new program for the reforms of chemical nomenclature to the Academy in 1787, for there was virtually no rational system of chemical nomenclature at this time. This work, titled Méthode de nomenclature chimique (Method of Chemical Nomenclature, 1787), introduced a new system which was tied inextricably to Lavoisier's new oxygen theory of chemistry.[38] The Classical elements of earth, air, fire, and water were discarded, and instead some 55 substances which could not be decomposed into simpler substances by any known chemical means were provisionally listed as elements. The elements included light; caloric (matter of heat); the principles of oxygen, hydrogen, and azote (nitrogen); carbon; sulfur; phosphorus; the yet unknown "radicals" of muriatic acid (hydrochloric acid), boric acid, and "fluoric" acid; 17 metals; 5 earths (mainly oxides of yet unknown metals such as magnesia, baria, and strontia); three alkalies (potash, soda, and ammonia); and the "radicals" of 19 organic acids. The acids, regarded in the new system as compounds of various elements with oxygen, were given names which indicated the element involved together with the degree of oxygenation of that element, for example sulfuric and sulfurous acids, phosphoric and phosphorous acids, nitric and nitrous acids, the "ic" termination indicating acids with a higher proportion of oxygen than those with the "ous" ending. Similarly, salts of the "ic" acids were given the terminal letters "ate," as in copper sulfate, whereas the salts of the "ous" acids terminated with the suffix "ite," as in copper sulfite. The total effect of the new nomenclature can be gauged by comparing the new name "copper sulfate" with the old term "vitriol of Venus." Lavoisier's new nomenclature spread throughout Europe and to the United States and became common use in the field of chemistry. This marked the beginning of the anti-phlogistic approach to the field.
Chemical revolution and opposition
Lavoisier is commonly cited as a central contributor to the chemical revolution. His precise measurements and meticulous keeping of balance sheets throughout his experiment were vital to the widespread acceptance of the law of conservation of mass. His introduction of new terminology, a binomial system modeled after that of Linnaeus, also helps to mark the dramatic changes in the field which are referred to generally as the chemical revolution. Lavoisier encountered much opposition in trying to change the field, especially from British phlogistic scientists. Joseph Priestley, Richard Kirwan, James Keir, and William Nicholson, among others, argued that quantification of substances did not imply conservation of mass.[39] Rather than reporting factual evidence, opposition claimed Lavoisier was misinterpreting the implications of his research. One of Lavoisier's allies, Jean Baptiste Biot, wrote of Lavoisier's methodology, "one felt the necessity of linking accuracy in experiments to rigor of reasoning."[39] His opposition argued that precision in experimentation did not imply precision in inferences and reasoning. Despite opposition, Lavoisier continued to use precise instrumentation to convince other chemists of his conclusions, often results to five to eight decimal places. Nicholson, who estimated that only three of these decimal places were meaningful, stated:
Lavoisier's fundamental contributions to chemistry were a result of a conscious effort to fit all experiments into the framework of a single theory. He established the consistent use of the chemical balance, used oxygen to overthrow the phlogiston theory, and developed a new system of chemical nomenclature which held that oxygen was an essential constituent of all acids (which later turned out to be erroneous).
Lavoisier also did early research in physical chemistry and thermodynamics in joint experiments with Laplace. They used a calorimeter to estimate the heat evolved per unit of carbon dioxide produced, eventually finding the same ratio for a flame and animals, indicating that animals produced energy by a type of combustion reaction.
Lavoisier also contributed to early ideas on composition and chemical changes by stating the radical theory, believing that radicals, which function as a single group in a chemical process, combine with oxygen in reactions. He also introduced the possibility of allotropy in chemical elements when he discovered that diamond is a crystalline form of carbon.
He was also responsible for the construction of the gasometer, an expensive instrument he used at his demonstrations. While he used his gasometer exclusively for these, he also created smaller, cheaper, more practical gasometers that worked with a sufficient degree of precision that more chemists could recreate.[46]
He was essentially a theorist, and his great merit lay in his capacity to take over experimental work that others had carried out—without always adequately recognizing their claims—and by a rigorous logical procedure, reinforced by his own quantitative experiments, expounding the true explanation of the results.[citation needed] He completed the work of Black, Priestley and Cavendish, and gave a correct explanation of their experiments.
Overall, his contributions are considered the most important in advancing chemistry to the level reached in physics and mathematics during the 18th century.[47]
https://en.wikipedia.org/wiki/Antoine_Lavoisier
https://en.wikipedia.org/wiki/Mikhail_Lomonosov
https://en.wikipedia.org/wiki/Joseph_Black
https://en.wikipedia.org/wiki/Henry_Cavendish
https://en.wikipedia.org/wiki/Jean_Rey_(physician)
https://en.wikipedia.org/wiki/Joseph_Priestley
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