In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, the mixing process of a solution happens at a scale where the effects of chemical polarity are involved, resulting in interactions that are specific to solvation. The solution assumes the characteristics of the solvent when the solvent is the fraction of the mixture. The concentration of a solute in a solution is the mass of that solute expressed as a percentage of the mass of the whole solution, a solution is a homogeneous mixture of two or more substances. The particles of solute in a solution cannot be seen by the naked eye, a solution does not allow beams of light to scatter. The solute from a solution cannot be separated by filtration and it is composed of only one phase. Homogeneous means that the components of the form a single phase. Heterogeneous means that the components of the mixture are of different phase, the properties of the mixture can be uniformly distributed through the volume but only in absence of diffusion phenomena or after their completion.
Usually, the present in the greatest amount is considered the solvent. Solvents can be gases, liquids or solids, one or more components present in the solution other than the solvent are called solutes. The solution has the physical state as the solvent. If the solvent is a gas, only gases are dissolved under a set of conditions. An example of a solution is air. Since interactions between molecules play almost no role, dilute gases form rather trivial solutions, in part of the literature, they are not even classified as solutions, but addressed as mixtures. If the solvent is a liquid, almost all gases, here are some examples, Gas in liquid, Oxygen in water Carbon dioxide in water – a less simple example, because the solution is accompanied by a chemical reaction. Liquid in liquid, The mixing of two or more substances of the same chemistry but different concentrations to form a constant, alcoholic beverages are basically solutions of ethanol in water. Solid in liquid, Sucrose in water Sodium chloride or any other salt in water, solutions in water are especially common.
Counterexamples are provided by liquid mixtures that are not homogeneous, body fluids are examples for complex liquid solutions, containing many solutes
Aluminium oxide or aluminum oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most commonly occurring of several aluminium oxides, and it is commonly called alumina, and may be called aloxide, aloxite, or alundum depending on particular forms or applications. It occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of form the precious gemstones ruby. Al2O3 is significant in its use to produce metal, as an abrasive owing to its hardness. Corundum is the most common naturally occurring form of aluminium oxide. Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colors to trace impurities, rubies are given their characteristic deep red color and their laser qualities by traces of chromium. Sapphires come in different colors given by various other impurities, such as iron, Al2O3 is an electrical insulator but has a relatively high thermal conductivity for a ceramic material.
Aluminium oxide is insoluble in water, in its most commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools. Aluminium oxide is responsible for the resistance of aluminium to weathering. Metallic aluminium is very reactive with oxygen, and a thin passivation layer of aluminium oxide forms on any exposed aluminium surface. This layer protects the metal from further oxidation, the thickness and properties of this oxide layer can be enhanced using a process called anodising. A number of alloys, such as bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance. Aluminium oxide was taken off the United States Environmental Protection Agencys chemicals lists in 1988, aluminium oxide is on EPAs Toxics Release Inventory list if it is a fibrous form. Al2O3 +6 HF →2 AlF3 +3 H2O Al2O3 +2 NaOH +3 H2O →2 NaAl4 The most common form of aluminium oxide is known as corundum.
The oxygen ions form a hexagonal close-packed structure with aluminium ions filling two-thirds of the octahedral interstices. In terms of its crystallography, corundum adopts a trigonal Bravais lattice with a group of R-3c. The primitive cell contains two units of aluminium oxide. Each has a crystal structure and properties
Sodium persulfate is the inorganic compound with the formula Na2S2O8. It is the salt of persulfate, an oxidizer. It is a solid that dissolves in water. It is almost non-hygroscopic and has good shelf-life, the salt is prepared by the electrolytic oxidation of sodium hydrogen sulfate,2 NaHSO4 → Na2S2O8 + H2 Oxidation is conducted at a platinum anode. In this way about 165,000 tons were produced in 2005, the standard redox potential of sodium persulfate into hydrogen sulfate is 2.1 V, which is higher than that of hydrogen peroxide but lower than ozone. The sulfate radical formed in situ has an electrode potential of 2.7 V. It is mainly used as an initiator for emulsion polymerization reactions for styrene based polymers such as Acrylonitrile butadiene styrene. Also applicable for accelerated curing of low formaldehyde adhesives and it is a bleach, both standalone and as a detergent component. It is a replacement for ammonium persulfate in etching mixtures for zinc and printed circuit boards and it is used as a soil conditioner and soil remediation and in manufacture of dyestuffs, modification of starch, bleach activator, desizing agent for oxidative desizing, etc.
Sodium persulfate is an oxidizing agent in chemistry, classically in the Elbs persulfate oxidation. It is used in reactions, for example in a synthesis of diapocynin from apocynin where iron sulfate is the radical initiator. The salt is an oxidizer and forms combustable mixtures with materials such as paper
Diamagnetic materials are repelled by a magnetic field, an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast and ferromagnetic materials are attracted by a magnetic field, diamagnetism is a quantum mechanical effect that occurs in all materials, when it is the only contribution to the magnetism the material is called diamagnetic. In paramagnetic and ferromagnetic substances the weak force is overcome by the attractive force of magnetic dipoles in the material. The magnetic permeability of diamagnetic materials is less than μ0, the permeability of vacuum, diamagnetism was first discovered when Sebald Justinus Brugmans observed in 1778 that bismuth and antimony were repelled by magnetic fields. In 1845, Michael Faraday demonstrated that it was a property of matter and he adopted the term diamagnetism after it was suggested to him by William Whewell. Diamagnetism, to a greater or lesser degree, is a property of all materials, for materials that show some other form of magnetism, the diamagnetic contribution becomes negligible.
Substances that mostly display diamagnetic behaviour are termed diamagnetic materials, or diamagnets, the magnetic susceptibility values of various molecular fragments are called Pascals constants. This means that diamagnetic materials are repelled by magnetic fields, since diamagnetism is such a weak property, its effects are not observable in everyday life. For example, the susceptibility of diamagnets such as water is χv = −9. 05×10−6. The most strongly diamagnetic material is bismuth, χv = −1. 66×10−4, these values are orders of magnitude smaller than the magnetism exhibited by paramagnets and ferromagnets. Note that because χv is derived from the ratio of the magnetic field to the applied field. All conductors exhibit an effective diamagnetism when they experience a magnetic field. The Lorentz force on electrons causes them to circulate around forming eddy currents, the eddy currents produce an induced magnetic field opposite the applied field, resisting the conductors motion. Superconductors may be considered perfect diamagnets, because they expel all fields due to the Meissner effect, however this effect is not due to eddy currents, as in ordinary diamagnetic materials.
If a powerful magnet is covered with a layer of water the field of the magnet significantly repels the water and this causes a slight dimple in the waters surface that may be seen by its reflection. Diamagnets may be levitated in stable equilibrium in a magnetic field, Earnshaws theorem seems to preclude the possibility of static magnetic levitation. However, Earnshaws theorem applies only to objects with positive susceptibilities and these are attracted to field maxima, which do not exist in free space. Diamagnets are attracted to field minima, and there can be a minimum in free space
Silver nitrate is an inorganic compound with chemical formula AgNO3. This compound is a precursor to many other silver compounds. It is far less sensitive to light than the halides and it was once called lunar caustic because silver was called luna by the ancient alchemists, who believed that silver was associated with the moon. In solid silver nitrate, the ions are three-coordinated in a trigonal planar arrangement. Albertus Magnus, in the 13th century, documented the ability of nitric acid to separate gold, Magnus noted that the resulting solution of silver nitrate could blacken skin. Silver nitrate can be prepared by reacting silver, such as a silver bullion or silver foil, with acid, resulting in silver nitrate, water. Reaction byproducts depend upon the concentration of acid used. 3 Ag +4 HNO3 →3 AgNO3 +2 H2O + NO Ag +2 HNO3 → AgNO3 + H2O + NO2 This is performed under a fume hood because of nitrogen oxide evolved during the reaction. A typical reaction with silver nitrate is to suspend a rod of copper in a solution of silver nitrate, silver nitrate is the least expensive salt of silver, it offers several other advantages as well.
It is non-hygroscopic, in contrast to silver fluoroborate and silver perchlorate and it is relatively stable to light. Finally, it dissolves in solvents, including water. The nitrate can be replaced by other ligands, rendering AgNO3 versatile. Treatment with solutions of halide ions gives a precipitate of AgX, silver nitrate is used to prepare some silver-based explosives, such as the fulminate, azide, or acetylide, through a precipitation reaction. This reaction is used in inorganic chemistry to abstract halides, Ag+ + X− → AgX where X− = Cl−, Br−. Other silver salts with non-coordinating anions, namely silver tetrafluoroborate and silver hexafluorophosphate are used for demanding applications. Similarly, this reaction is used in chemistry to confirm the presence of chloride, bromide. Samples are typically acidified with nitric acid to remove interfering ions, e. g. carbonate ions. This step avoids confusion of silver sulfide or silver carbonate precipitates with that of silver halides, the color of precipitate varies with the halide, pale yellow/cream, yellow
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume.
In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume.
As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
Boron trioxide is one of the oxides of boron. It is a white, glassy solid with the formula B2O3 and it is almost always found as the vitreous form, however, it can be crystallized after extensive annealing. Glassy boron oxide is thought to be composed of rings which are six-membered rings composed of alternating 3-coordinate boron. The crystalline form is composed of BO3 triangles. This trigonal, quartz-like network undergoes a transformation to monoclinic β-B2O3 at several gigapascals. Boron trioxide is produced by treating borax with sulfuric acid in a fusion furnace, at temperatures above 750 °C, the molten boron oxide layer separates out from sodium sulfate. It is decanted and obtained in 96–97% purity, another method is heating boric acid above ~300 °C. Boric acid will initially decompose into water steam and metaboric acid at around 170 °C, the reactions are, H3BO3 → HBO2 + H2O2 HBO2 → B2O3 + H2O Boric acid goes to anhydrous microcrystalline B2O3 in a heated fluidized bed. Carefully controlled heating rate avoids gumming as water evolves, internally graphitized tubes via acetylene thermal decomposition are passivated.
Crystallization of molten α-B2O3 at ambient pressure is strongly kinetically disfavored, threshold conditions for crystallization of the amorphous solid are 10 kbar and ~200 °C. Its proposed crystal structure in space groups P31, P32 has been revised to enantiomorphic space groups P3121, P3221. Material Safety Data Sheet CDC - NIOSH Pocket Guide to Chemical Hazards - Boron oxide
The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs.
Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer.
For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
A silver-oxide battery is a primary cell with a very high energy to weight ratio. Available either in small sizes as button cells, or in custom designed batteries where the superior performance of the silver-oxide chemistry outweighs cost considerations. These larger cells are found in applications for the military. In recent years they have become important as reserve batteries for manned and unmanned spacecraft, spent batteries can be processed to recover their silver content. Silver-oxide primary batteries account for over 20% of all battery sales in Japan. A related rechargeable secondary battery usually called a silver–zinc battery uses a variation of silver–oxide chemistry and it shares most of the characteristics of the silver-oxide battery, and in addition, is able to deliver one of the highest specific energies of all presently known electrochemical power sources. Long used in specialized applications, it is now being developed for more mainstream markets, a silver-oxide battery uses silver oxide as the positive electrode, zinc as the negative electrode plus an alkaline electrolyte, usually sodium hydroxide or potassium hydroxide.
The silver is reduced at the cathode from Ag to Ag, the electrolyte used is a potassium hydroxide / water solution. The process is continued until the cell reaches a level where the decomposition of the electrolyte is possible at about 1.55 Volts. This is taken as the end of a charge, as no charge is stored. Compared to other batteries, a silver oxide battery has an open circuit potential than a mercury battery. This technology had the highest energy density prior to lithium technologies, primarily developed for aircraft, they have long been used in space launchers and crewed spacecraft where their short cycle life is not a drawback. Non-rechargeable silver–zinc batteries powered the first Soviet Sputnik satellites as well as US Saturn launch vehicles, the primary power sources for the command module were the hydrogen/oxygen fuel cells in the service module. Only these batteries were recharged in flight, after the Apollo 13 near-disaster, an auxiliary silver–zinc battery was added to the service module as a backup to the fuel cells.
Silver oxide batteries become hazardous on the onset of leakage, this generally takes five years from the time they are put into use, until recently, all silver oxide batteries contained up to 0. 2% mercury. The mercury was incorporated into the anode to inhibit corrosion in the alkaline environment. Sony started producing the first silver oxide batteries without added mercury in 2004, history of the battery Secondary cell Fuel cell Battery recycling List of battery types List of battery sizes Comparison of battery types Battery nomenclature
Cerium oxide, known as ceric oxide, ceric dioxide, cerium oxide or cerium dioxide, is an oxide of the rare earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO2 and it is an important commercial product and an intermediate in the purification of the element from the ores. The distinctive property of material is its reversible conversion to a nonstoichiometric oxide. Cerium occurs naturally as a mixture with other rare elements in its principal ores bastnaesite and monazite. After extraction of the ions into aqueous base, Ce is separated from that mixture by addition of an oxidant followed by adjustment of the pH. This step exploits the low solubility of CeO2 and the fact that other rare earth elements resist oxidation, cerium oxide is formed by the calcination of cerium oxalate or cerium hydroxide. Cerium forms cerium oxide, Ce 2O3, which is an unstable that will oxidize to cerium oxide, cerium oxide adopts the fluorite structure, space group Fm3m, #225 containing 8-coordinate Ce4+ and 4 coordinate O2−.
At high temperatures it releases oxygen to give a non-stoichiometric, anion deficient form that retains the fluorite lattice and this material has the formula CeO where 0 < x <0.28. The value of x depends on both the temperature and the partial pressure. The equation =106000 × P O2 −0.217 exp has been shown to predict the equilibrium non stoichiometry x over a range of oxygen partial pressures and temperatures. The non stoichiometric form has a blue to black color, the number of oxygen vacancies is frequently measured by using X-ray photoelectron spectroscopy to compare the ratios of Ce3+to Ce4+. In the most stable phase of ceria, it exhibits several defects depending on partial pressure of oxygen or stress state of the material. The primary defects of concern are oxygen vacancies and small polarons, increases in the number of oxygen defects increases the diffusion rate of oxide in the lattice as reflected in an increase in ionic conductivity. These factors recommend ceria as an electrolyte in solid-oxide fuel cells.
Undoped and doped ceria exhibit high conductivity at low partial pressures of oxygen due to reduction of the cerium ion leading to the formation of small polarons. Since the oxygen atoms in a ceria crystal occur in planes, the diffusion rate increases as the defect concentration increases. The principal application of ceria is for polishing, especially chemical-mechanical planarization, for this purpose, it has displaced many other oxides that were previously used, such as iron oxide and zirconia. For hobbyists, it is known as opticians rouge
Arsenic trioxide is an inorganic compound with the formula As 2O3. This commercially important oxide of arsenic is the precursor to other arsenic compounds. Approximately 50,000 tonnes are produced annually, many applications are controversial given the high toxicity of arsenic compounds. Arsenic trioxide can be generated via processing of arsenic compounds including the oxidation of arsenic. Illustrative is the roasting of orpiment, an arsenic sulfide ore. 2 As 2S3 +9 O2 →2 As 2O3 +6 SO2 Most arsenic oxide is, for example, arsenopyrite, a common impurity in gold- and copper-containing ores, liberates arsenic trioxide upon heating in air. The processing of minerals has led to numerous cases of poisonings. Only in China are arsenic ores intentionally mined, in the laboratory, it is prepared by hydrolysis of arsenic trichloride,2 AsCl3 +3 H2O → As2O3 +6 HCl As 2O3 occurs naturally as two minerals and claudetite. Both are relatively rare secondary minerals found in zones of As-rich ore deposits. Sheets of As2O3 stand for part of structures of the recently discovered minerals lucabindiite, As4O6, Arsenic trioxide is an amphoteric oxide, and its aqueous solutions are weakly acidic.
Thus, it dissolves readily in alkaline solutions to give arsenites and it is less soluble in acids, although it will dissolve in hydrochloric acid. Reduction gives elemental arsenic or arsine depending on conditions, As2O3 +6 Zn +12 HNO3 →2 AsH3 +6 Zn2 +3 H2O This reaction is used in the Marsh test. In the liquid and gas phase below 800 °C, arsenic trioxide has the formula As 4O6 and is isostructural with P 4O6, above 800 °C As 4O6 significantly dissociates into molecular As 2O3, which adopts the same structure as N 2O3. Three forms are known in the state, a high temperature cubic As 4O6, containing molecular As 4O6. The polymers, which both crystallize as monoclinic crystals, feature sheets of pyramidal AsO3 units that share O atoms, large scale applications include its use as a precursor to forestry products, in colorless glass production, and in electronics. Being the main compound of arsenic, the trioxide is the precursor to elemental arsenic, arsenic alloys, organoarsenic compounds, e. g. feed additives and pharmaceuticals, are derived from arsenic trioxide.
Bulk arsenic-based compounds sodium arsenite and sodium cacodylate are derived from the trioxide, a variety of applications exploit arsenics toxicity, including the use of the oxide as a wood preservative. Copper arsenates, which are derived from arsenic trioxide, are used on a scale as a wood preservative in the US and Malaysia
Bismuth oxide is perhaps the most industrially important compound of bismuth. It is a starting point for bismuth chemistry. It is found naturally as the mineral bismite and sphaerobismoite, but it is obtained as a by-product of the smelting of copper. Bismuth trioxide is used to produce the Dragons eggs effect in fireworks. The structures adopted by Bi2O3 differ substantially from those of oxide, As2O3. Bismuth oxide, Bi2O3 has five crystallographic polymorphs, the room temperature phase, α-Bi2O3 has a monoclinic crystal structure. There are three high temperature phases, a tetragonal β-phase, a body-centred cubic γ-phase, a cubic δ-Bi2O3 phase, the room temperature α-phase has a complex structure with layers of oxygen atoms with layers of bismuth atoms between them. The bismuth atoms are in two different environments which can be described as distorted 6 and 5 coordinate respectively, β-Bi2O3 has a structure related to fluorite. γ-Bi2O3 has a related to that of Bi12SiO20, where a fraction of the Bi atoms occupy the position occupied by SiIV.
δ- Bi2O3 has a defective fluorite-type crystal structure in two of the eight oxygen sites in the unit cell are vacant. ε- Bi2O3 has a related to the α- and β- phases. It can be prepared by means and transforms to the α- phase at 400 °C. The monoclinic α-phase transforms to the cubic δ-Bi2O3 when heated above 729 °C, the behaviour of Bi2O3 on cooling from the δ-phase is more complex, with the possible formation of two intermediate metastable phases, the tetragonal β-phase or the body-centred cubic γ-phase. The γ-phase can exist at room temperature with very slow cooling rates, the α-phase exhibits p-type electronic conductivity at room temperature which transforms to n-type conductivity between 550 °C and 650 °C, depending on the oxygen partial pressure. The conductivity in the β, γ and δ-phases is predominantly ionic with oxide ions being the charge carrier. Of these δ- Bi2O3 has the highest reported conductivity, at 750 °C the conductivity of δ- Bi2O3 is typically about 1 Scm−1, about three orders of magnitude greater than the intermediate phases and four orders greater than the monoclinic phase.
The conductivity in the β, γ and δ-phases is predominantly ionic with oxide ions being the charge carrier. δ- Bi2O3 has a defective fluorite-type crystal structure in two of the eight oxygen sites in the unit cell are vacant