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Mercury Beating Heart
The mercury beating heart is an electrochemical redox reaction between the elements mercury, iron and chromium. The reaction causes a blob of mercury in water to oscillate. The observeable reaction demonstrates an effect of a non-homogeneous electrical double layer. It is often used as a classroom demonstration. The experiment In the experiment a droplet of mercury is placed in a watch glass, immersed in an electrolyte such as sulfuric acid which contains an oxidizing agent such as hydrogen peroxide, potassium permanganate, or potassium dichromate. The tip of an iron nail is positioned almost touching the mercury. If the position of the nail tip is just right, the mercury blob begins to oscillate, changing shape. The explanation In one variation the mechanism is thought to be the following: The dichromate oxidizes the mercury, forming a layer of mercury oxide. In the process the dichromate is reduced to the chromium(III) ion. The oxidized layer on the mercury reduces the surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrochemistry
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving via an electronically-conducting phase (typically an external electrical circuit, but not necessarily, as in electroless plating) between electrodes separated by an ionically conducting and electronically insulating electrolyte (or ionic species in a solution). When a chemical reaction is driven by an electrical potential difference, as in electrolysis, or if a potential difference results from a chemical reaction as in an electric battery or fuel cell, it is called an ''electrochemical'' reaction. Unlike in other chemical reactions, in electrochemical reactions electrons are not transferred directly between atoms, ions, or molecules, but via the af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The National Academy Of Sciences Of The United States Of America
''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Sciences, published since 1915, and publishes original research, scientific reviews, commentaries, and letters. According to ''Journal Citation Reports'', the journal has a 2021 impact factor of 12.779. ''PNAS'' is the second most cited scientific journal, with more than 1.9 million cumulative citations from 2008 to 2018. In the mass media, ''PNAS'' has been described variously as "prestigious", "sedate", "renowned" and "high impact". ''PNAS'' is a delayed open access journal, with an embargo period of six months that can be bypassed for an author fee ( hybrid open access). Since September 2017, open access articles are published under a Creative Commons license. Since January 2019, ''PNAS'' has been online-only, although print issues are ava ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrochemistry
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving via an electronically-conducting phase (typically an external electrical circuit, but not necessarily, as in electroless plating) between electrodes separated by an ionically conducting and electronically insulating electrolyte (or ionic species in a solution). When a chemical reaction is driven by an electrical potential difference, as in electrolysis, or if a potential difference results from a chemical reaction as in an electric battery or fuel cell, it is called an ''electrochemical'' reaction. Unlike in other chemical reactions, in electrochemical reactions electrons are not transferred directly between atoms, ions, or molecules, but via the af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( ) from the Greek words, ''hydor'' (water) and ''argyros'' (silver). A heavy, silvery d-block A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-blo ... element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature. Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by Mill (grinding), grinding natural cinnabar or synthetic mercuric sulfide. Mercury is used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Oscillator
A chemical oscillator is a complex mixture of reacting chemical compounds in which the concentration of one or more components exhibits periodic changes. They are a class of reactions that serve as an example of non-equilibrium thermodynamics with far-from-equilibrium behavior. The reactions are theoretically important in that they show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior. In cases where one of the reagents has a visible color, periodic color changes can be observed. Examples of oscillating reactions are the Belousov–Zhabotinsky reaction (BZ reaction), the Briggs–Rauscher reaction, and the Bray–Liebhafsky reaction. History The earliest scientific evidence that such reactions can oscillate was met with extreme scepticism. In 1828, G.T. Fechner published a report of oscillations in a chemical system. He described an electrochemical cell that produced an oscillating current. In 1899, W. Ostwald observed that the rate of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Bottle Reaction
The blue bottle experiment is a color-changing redox chemical reaction. An aqueous solution containing glucose, sodium hydroxide, methylene blue is prepared in a closed bottle containing some air. Upon standing, it spontaneously turns from blue to colorless due to reduction of methylene blue by the alkaline glucose solution. However, shaking the bottle oxidizes methylene blue back into its blue form. With further shaking, this color-change cycle can be repeated many times. This experiment is a classic chemistry demonstration that can be used in laboratory courses as a general chemistry experiment to study chemical kinetics and reaction mechanism. The reaction also works with other reducing agents besides glucose and other redox indicator dyes besides methylene blue. Reactions History and general concept The mechanism of the blue bottle experiment requires an understanding of rates and mechanisms of complex interacting chemical reactions. In complex chemical reactions, indi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barking Dog Reaction
The "Barking Dog" is an exothermic chemical reaction that results from the ignition of a mixture of carbon disulfide and nitrous oxide. When ignited in a cylindrical tube, the reaction produces a bright flash and a loud " woof" - reminiscent of a barking dog. In simple terms, the 'Barking Dog' reaction is a combustion process, in which a fuel (carbon disulfide, CS2) reacts with an oxidizing agent (nitrous oxide, N2O), producing heat and elemental sulfur. The flame front in the reaction is a zone of very hot, luminous gas, produced by the reactants decomposing. :8 N2O + 4 CS2 → S8 + 4 CO2 + 8 N2 In April 1853, Justus von Liebig Justus Freiherr von Liebig (12 May 1803 – 20 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at t ... performed the demonstration in front of the Bavarian royal family; however, the glass container sha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Garden
Comparison of chemical gardens grown by NASA scientists on the International Space Station (left) and on the ground (right) A chemical garden while growing up Cobalt(II) chloride upA chemical garden A chemical garden is a set of complex biological-looking structures created by mixing inorganic chemicals. Chemical gardening is an experiment in chemistry usually performed by adding metal salts, such as copper sulfate or cobalt(II) chloride, to an aqueous solution of sodium silicate (otherwise known as waterglass). This results in the growth of plant-like forms in minutes to hours. The chemical garden was first observed and described by Johann Rudolf Glauber in 1646. In its original form, the chemical garden involved the introduction of ferrous chloride (FeCl2) crystals into a solution of potassium silicate (K2SiO3). Process The chemical garden relies on most transition metal silicates being insoluble in water and colored. When a metal salt, such as cobalt chloride, is ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine to the adenosine A1 receptor, which enhances release of the neurotransmitter acetylcholine. Caffeine has a three-dimensional structure similar to that of adenosine, which allows it to bind and block its receptors. Caffeine also increases cyclic AMP levels through nonselective inhibition of phosphodiesterase. Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, fruits, nuts, or leaves of a number of plants native to Africa, East Asia and South America, and helps to protect them against herbivores and from competition by preventing the germination of nearby seeds, as well as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedlieb Ferdinand Runge
Friedlieb Ferdinand Runge (8 February 1794 – 25 March 1867) was a German analytical chemist. Runge identified the mydriatic (pupil dilating) effects of belladonna (deadly nightshade) extract, identified caffeine, and discovered the first coal tar dye ( aniline blue). Early life Friedlieb Ferdinand Runge was born near Hamburg on 8 February 1794. From a young age, Runge conducted chemical experiments, serendipitously identifying the mydriatic (pupil dilating) effects of belladonna (deadly nightshade) extract. Career In 1819, Runge was invited to show Goethe how belladonna caused dilation of the pupil, which Runge did, using a cat as an experimental subject. Goethe was so impressed with the demonstration that :"Nachdem Goethe mir seine größte Zufriedenheit sowol über die Erzählung des durch scheinbaren schwarzen Staar Geretteten, wie auch über das andere ausgesprochen, übergab er mir noch eine Schachtel mit Kaffeebohnen, die ein Grieche ihm als etwas Vorzügliches gesand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Henry (chemist)
William Henry (12 December 17742 September 1836) was an English chemist. He was the son of Thomas Henry and was born in Manchester England. He developed what is known today as Henry's Law. Life William Henry was apprenticed to Thomas Percival and later worked with John Ferriar & John Huit at the Manchesters Infirmary. He began to study medicine at University of Edinburgh in 1795, taking his medical in 1807, but ill-health interrupted his practice as a physician, and he devoted his time mainly to chemical research, especially with regard to gases. One of his best-known papers (published in ''Philosophical Transactions of the Royal Society'', 1803) describes experiments on the quantity of gases absorbed by water at different temperatures and under different pressures. His results are known today as Henry's law. His other papers deal with gas-analysis, fire-damp, illuminating gas, the composition of hydrochloric acid and of ammonia, urinary and other morbid concretions, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alessandro Volta
Alessandro Giuseppe Antonio Anastasio Volta (, ; 18 February 1745 – 5 March 1827) was an Italian physicist, chemist and lay Catholic who was a pioneer of electricity and power who is credited as the inventor of the electric battery and the discoverer of methane. He invented the voltaic pile in 1799, and reported the results of his experiments in 1800 in a two-part letter to the president of the Royal Society. With this invention Volta proved that electricity could be generated chemically and debunked the prevalent theory that electricity was generated solely by living beings. Volta's invention sparked a great amount of scientific excitement and led others to conduct similar experiments, which eventually led to the development of the field of electrochemistry. Volta also drew admiration from Napoleon Bonaparte for his invention, and was invited to the Institute of France to demonstrate his invention to the members of the institute. Volta enjoyed a certain amount of closeness ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
