Moreover, previous studies have indicated that these reaction centers can be platinized.
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Add 5 g of platinized zinc and immediately seal the flask with the tube prepared in advance.
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After two hours of contact, wash the zinc with distilled water, drain the platinized zinc on several thicknesses of blotting paper, dry and place in a dry bottle.
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No oxygen is consumed, and hence the sensor is insensitive to stirring, but the signal will stabilize more quickly if the sensor is stirred after being put in the sample. These type of electrode sensors can be used for in situ and real-time monitoring of oxygen production in water-splitting reactions. The platinized electrodes can accomplish the real-time monitoring of hydrogen production in water-splitting device. Planar optodes are used to detect the spatial distribution of oxygen concentrations in a platinized foil.
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To prevent loss of the liquid during long-term storage, it is therefore intentionally converted to the para isomer as part of the production process, typically using a catalyst such as iron(III) oxide, activated carbon, platinized asbestos, rare earth metals, uranium compounds, chromium(III) oxide, or some nickel compounds.
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A. Wieckowski and J. Sobkowski, "Comparative study of adsorption and oxidation of formic acid and methanol on platinized electrodes in acidic solution", Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1975, 63 (3), 365–377.A. Wieckowski, Direct radiometric study of electrosorption of tritium labeled compounds. Adsorption of methanol on gold electrodes, Journal of the Electrochemical Society, 1975, 122 (2), 252–254.
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The first confirmed synthesis of cyclopropene, carried out by Dem'yanov and Doyarenko, involved the thermal decomposition of trimethylcyclopropylammonium hydroxide over platinized clay at 320–330 °C under a CO2 atmosphere. This reaction produces mainly trimethylamine and dimethylcyclopropyl amine, together with about 5% of cyclopropene. Cyclopropene can also be obtained in about 1% yield by thermolysis of the adduct of cycloheptatriene and dimethyl acetylenedicarboxylate.
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Platinum black is widely used as a thin film covering solid platinum metal, forming platinum electrodes for applications in electrochemistry. The process of covering platinum electrodes with such a layer of platinum black is called "platinization of platinum". The platinized platinum has a true surface area much higher than the geometrical surface area of the electrode and, therefore, exhibits action superior to that of shiny platinum.
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The Daniell cell was largely replaced by the Smee cell (amalgamated zinc and platinized silver in sulfuric acid) after the latter's invention by Alfred Smee in 1840. Both of these cells are forerunners of contemporary electrical batteries. By the 1870s, mechanical generators were being used; the larger currents that could be sustained by generators enabled substantial increases in the rate of metal deposition during electrotyping.
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The Wolff–Kishner reduction was discovered independently by N. Kishner in 1911 and Ludwig Wolff in 1912. Kishner found that addition of pre-formed hydrazone to hot potassium hydroxide containing crushed platinized porous plate led to formation of the corresponding hydrocarbon. A review titled “Disability, Despotism, Deoxygenation—From Exile to Academy Member: Nikolai Matveevich Kizhner” describing the life and work of Kishner was published in 2013. Scheme 2.
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Because of the high adsorption activity of the platinized platinum electrode, it's very important to protect electrode surface and solution from the presence of organic substances as well as from atmospheric oxygen. Inorganic ions that can reduce to a lower valency state at the electrode also have to be avoided (e.g., Fe3+, ). A number of organic substances are also reduced by hydrogen at a platinum surface, and these also have to be avoided.
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Prototype International Meter bar From 1889 to 1960, the meter was defined as the length of a platinum-iridium (90:10) alloy bar, known as the international prototype of the meter. The previous bar was made of platinum in 1799. Until May 2019, the kilogram was defined as the mass of the international prototype of the kilogram, a cylinder of the same platinum-iridium alloy made in 1879. The standard hydrogen electrode also uses a platinized platinum electrode due to its corrosion resistance, and other attributes.
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Scheme of the standard hydrogen electrode The scheme of the standard hydrogen electrode: # platinized platinum electrode # hydrogen gas # solution of the acid with activity of H+ = 1 mol dm−3 # hydroseal for preventing oxygen interference # reservoir through which the second half- element of the galvanic cell should be attached. The connection can be direct, through a narrow tube to reduce mixing, or through a salt bridge, depending on the other electrode and solution. This creates an ionically conductive path to the working electrode of interest.
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Due to the corrosive nature of chlorine production, the anode (where the chlorine is formed) must be non-reactive and has been made from platinum metal, graphite (called plumbago in Faraday's time), platinized titanium. A mixed metal oxide clad titanium anode (also called a dimensionally stable anode) is the industrial standard today. Historically, platinum, magnetite, lead dioxide, manganese dioxide, and ferrosilicon (13-15% silicon) have also been used as anodes. Platinum alloyed with iridium is more resistant to corrosion from chlorine than pure platinum.
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Unlike the zinc electrode, the copper or platinized silver electrodes are not consumed by using the battery, and the details of this electrode do not affect the cell's voltage. The Smee cell was convenient for electrotyping, which produced copper plates for letterpress printing of newspapers and books, and also statues and other metallic objects. The Smee cell used amalgamated zinc instead of pure zinc; the surface of amalgamated zinc has been treated with mercury. Apparently amalgamated zinc was less prone to degradation by an acidic solution than is pure zinc.
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The effect of oxygen was known early in the 19th century when wet- cell Leclanche batteries absorbed atmospheric oxygen into the carbon cathode current collector. In 1878, a porous platinized carbon air electrode was found to work as well as the manganese dioxide () of the Leclanche cell. Commercial products began to be made on this principle in 1932 when George W. Heise and Erwin A. Schumacher of the National Carbon Company built cells, treating the carbon electrodes with wax to prevent flooding. This type is still used for large zinc–air cells for navigation aids and rail transportation.
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From 1840 to the late 19th century, large, voltaic cells using a zinc electrode and a sulfuric acid electrolyte were widely used in the printing industry. While copper electrodes like those in lemon batteries were sometimes used, in 1840 Alfred Smee invented a refined version of this cell that used silver with a rough platinum coating instead of a copper electrode. Hydrogen gas clinging to the surface of a silver or copper electrode reduces the electric current that can be drawn from a cell; the phenomenon is called "polarization". The roughened, "platinized" surface speeds up the bubbling of the hydrogen gas, and increases the current from the cell.
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At room temperature, hydrogen contains 75% orthohydrogen, a proportion which the liquefaction process preserves if carried out in the absence of a catalyst like ferric oxide, activated carbon, platinized asbestos, rare earth metals, uranium compounds, chromic oxide, or some nickel compounds to accelerate the conversion of the liquid hydrogen into parahydrogen. Alternatively, additional refrigeration equipment can be used to slowly absorb the heat that the orthohydrogen fraction will (more slowly) release as it spontaneously converts into parahydrogen. If orthohydrogen is not removed from rapidly liquified hydrogen, without a catalyst, the heat released during its decay can boil off as much as 50% of the original liquid.
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The ortho/para distinction also occurs in other hydrogen-containing molecules or functional groups, such as water and methylene, but is of little significance for their thermal properties. The ortho form that converts to the para form slowly at low temperatures. The ortho/para ratio in condensed H2 is an important consideration in the preparation and storage of liquid hydrogen: the conversion from ortho to para is exothermic and produces enough heat to evaporate some of the hydrogen liquid, leading to loss of liquefied material. Catalysts for the ortho-para interconversion, such as ferric oxide, activated carbon, platinized asbestos, rare earth metals, uranium compounds, chromic oxide, or some nickel compounds, are used during hydrogen cooling.
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