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Start on. Show related SlideShares at end. WordPress Shortcode. Published in: Lifestyle. Full Name Comment goes here. Are you sure you want to Yes No. Be the first to like this. More than black-and-white line illustrations. A Standing Order Plan saves you both time and money without risking a penny of your acquisitions budget. The number of copies you indicate of each new title under the plan you select will automatically as the new edition becomes available.
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The millibar mb is more common; it is used for measuring atmospheric pressure in meteorology. Barft process A process formerly used for protecting iron from corrosion by heating it in steam, to form a layer of tri-iron tetroxide Fe3O4. Barium carbonate can be readily precipitated by adding an alkali carbonate to a barium salt solution. The electronic configuration is that of xenon with two additional outer 6s electrons.
The metal is obtained by the electrolysis of the fused chloride using a cooled cathode which is slowly withdrawn from the melt. Because of its low melting point barium is readily purified by vacuum distillation. Barium has a low ionization potential and a large radius. It is therefore strongly electropositive and its properties, and those of its compounds, are very similar to those of the other alkaline-earth elements calcium and strontium.
Notable differences in the chemistry of barium from the rest of the group are: 1. The much higher stability of the carbonate. Barium chloride is used as the electrolyte in the extraction of barium, as a rat poison, and in the leather industry. Barium hydroxide is the most soluble of the group 2 hydroxides and can be used in volumetric analysis for the estimation of weak acids using phenolphthalein as an indicator. In this treatment the ions of classical mineral acids such as SO42— and NO3— are weak conjugate bases of their respective acids.
Electron-pair donors, such as trimethylamine and pyridine, are examples of organic bases. It has been used in the manufacture of lubricating-oil additives. Barium peroxide is used for bleaching straw and silk and in the laboratory preparation of hydrogen peroxide. Typical base-catalyzed reactions are the Claisen condensation and the aldol reaction, in which the first step is abstraction of a proton to give a carbanion. Barium sulfate is very insoluble in water and can be prepared easily as a precipitate by adding sulfuric acid to barium chloride.
Barium sulfate is an important industrial chemical. It is also used in the glass and rubber industries and medically taken orally to allow radiographs to be taken of the digestive system. See also SI units.
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Thus any solution in which the concentration of OH— ions is greater than that in pure water at the same temperature is described as basic; i. The barn is sometimes used to express the effective cross-sections of atoms or nuclei in the scattering or absorption of particles. It is equal to liters about 29 US gallons.
It consists mainly of fine crystals of pyroxine and plagioclase feldspar. Basic solutions have a pH greater than 7. The thermometer can thus be set for any particular range of working temperature. It is named for the German chemist Ernst Otto Beckmann — CuCl2, Cu OH 2. The hydroxyhalides are essentially closely packed assemblies of OH— with metal or halide ions in the octahedral holes.
The hydroxy-oxy salts have more complex structures than those implied by the formulae. At any particular instant all the material, from its preparation to the final product, has reached a definite stage in the process. Baking a cake is an example of a batch process. Such processes present problems of automation and instrumentation and tend to be wasteful of energy. For this reason, batch processing is only economically operated on an industrial scale when small quantities of valuable or strategic materials are required, e.
Compare continuous process. The unit is named for the French physicist Antoine Henri Becquerel — The process is sometimes described as ore dressing. If a number of identical cells are connected in series, the total e. If the cells are in parallel, the e. The gelatinous suspension it forms with water is used to bind together the sand for making iron castings.
Chemically bentonite is an aluminosilicate of variable composition. See body-centered cubic crystal. First discovered by the German chemist Ernst Otto Beckmann — , it is used in the manufacture of polyamides. Benzene is a highly toxic compound and continued inhalation of the vapor is harmful.
It was originally isolated from coal tar and for many years this was the principal source of the compound. This anomolous behavior can now be explained by assuming that the six pi electrons are delocalized and that benzene is, therefore, a resonance hybrid. It is used as a food preservative. The carboxyl group —COOH directs further substitution onto the benzene ring in the 3 position.
Benzenecarbaldehyde undergoes the reactions characteristic of aldehydes and may be synthesized in the laboratory 32 benzoyl group benzene-1,2-dicarboxylic OH acid phthalic acid; C6H4 COOH 2 A white crystalline aromatic acid. On heating it loses water to form phthalic anhydride, which is used to make dyestuffs and polymers for plasticizers and plastics.
See also quinone. Any further substitution onto the benzene ring is directed into the 3 position. See also benzene. COOH The reaction, which involves migration of a phenyl group C6H5— from one carbon atom to another, was the first rearrangement reaction to be described by Justus von Liebig in See ben- benzoyl group See benzenecarbonyl group.
It occurs in coal tar and tobacco smoke and has strong carcinogenic properties. The element accounts for only 0. The metal is obtained by conversion of the ore to the sulfate at high temperature and pressure with concentrated sulfuric acid, then to the chloride, followed by electrolysis of the fused chloride. Alternatively, extraction by hydrogen fluoride followed by electrolysis of the fused fluoride may be employed. The metal has a much lower general reactivity than lithium or other elements in group 2. It is used as an antioxidant and hardener in some alloys, such as copper and phosphor bronzes.
Beryllium has the highest ionization potential of group 2 and the smallest size. Consequently it is less electropositive and more polarizing than other members of the group. The metal reacts directly with oxygen, nitrogen, sulfur, and the halogens at various elevated temperatures, to form the oxide BeO, nitride Be3N2, sulfide BeS, and halides BeX2, all of which are covalent.
Beryllium does not react directly with hydrogen but a polymeric hydride BeH2 n can be prepared by reduction of CH3 2Be using lithium tetrahydridoaluminate. The hydroxide is only weakly basic. The element does not form a true carbonate; the basic beryllium carbonate, BeCO3. Be OH 2 is formed when sodium carbonate is added to solutions of beryllium compounds. Beryllium hydride, chloride, and dimethylberyllium form polymeric bridged species but, whereas the bridging in the chloride is via an electron pair on chlorine atoms and can be regarded as an electronpair donor bond, the bonding in the hydride and in the methyl compound involves two-electron three-centre bonds.
The ring of six carbon atoms contains two double bonds and one triple bond the systematic name is 1,2-didehydrobenzene. A powdered mixture of coal, heavy oil, and a catalyst was heated with hydrogen at high pressure. Several radioisotopes have been synthesized. The metal reacts with oxygen, steam, and acids. Symbol: Bk; m. There are several varieties including the gemstones emerald colored green by traces of chromium oxide and aquamarine a bluegreen color. Beryllium also forms a number of alkyl compounds, some of which can be stabilized by coordination.
Beryllium is extremely toxic. Symbol: Be; m. Beryllium oxide is used for the production of beryllium and beryllium-copper refractories, for high-output transistors, and for printed circuits. The chemical properties of beryllium oxide are similar to those of aluminum oxide. The resulting solution is evaporated and filtered in an atmosphere of carbon dioxide. On heating, it breaks down to give the oxide. When heated in the presence of water, it readily dissolves to give an acidic solution.
It is a poor conductor in the fused state and in the solid form consists of a covalent polymeric structure. It is readily soluble in organic solvents but is hydrolyzed in the presence of water to give the hydroxide. The anhydrous salt is used as a catalyst. A vertical cylindrical steel vessel converter is used, lined with a refractory material. Air is blown through the molten iron and carbon is oxidized and thus removed from the iron.
Other impurities — silicon, sulfur, and phosphorus — are also oxidized. Irons containing large amounts of phosphorus are treated in a converter lined with a basic material, so that a phosphate slag is formed. The required amount of carbon is then added to the iron to produce the desired type of steel. The process is named for the British inventor and engineer Sir Henry Bessemer — In an excess of alkali, beryllium hydroxide dissolves to give a beryllate, Be OH 42—. In this way, beryllium and aluminum hydroxides are similar and the reaction is an indication that beryllium hydroxide is amphoteric.
The prefix indicates the presence of hydrogen; for instance, sodium bisulfate NaHSO4 is sodium hydrogensulfate, etc. An organic compound having a structure in which two phenyl groups are joined by a C—C bond. See also polychlorinated biphenyl. See also nitrogen fixation. Fe2O3 or NaCl. It is therefore a measure of the quantity of organic pollutants present. It is found by measuring the amount of oxygen in a sample of water, keeping the sample and then making the measurement again five days later. It occurs native and in the ores Bi2S3 and Bi2O3.
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The element does not react with oxygen or water under normal temperatures. It can be dissolved by concentrated nitric acid. Bismuth is widely used in alloys, especially low-melting alloys. The element has the property of expanding when it solidifies. Compounds of bismuth are used in cosmetics and medicines. Symbol: Bi; m. Many enzymes have active metal atoms and bioinorganic compounds are important in other roles such as protein folding, oxygen transport, and electron transfer.
Two important examples of bioinorganic compounds are hemoglobin containing iron and chlorophyll containing magnesium. It can be prepared by direct combination of bismuth and chlorine. Bismuth V chloride does not form. It is the common type of coal used for domestic and industrial purposes. See also anthracite. Bismuth III nitrate oxide is used in pharmaceutical preparations. See bismuth III chloride. A mixture of the ore with coke and a flux is heated by preheated air blown into the bottom of the furnace.
The flux is often calcium oxide from limestone. Molten pig iron is run off from the bottom of the furnace. All bleaches are oxidizing agents, and include chlorine, sodium chlorate I solution NaClO, sodium hypochlorite , hydrogen peroxide, and sulfur IV oxide. Sunlight also has a bleaching effect. It is prepared on a large scale by passing a current of chlorine through a tilted cylinder down which is passed calcium hydroxide. Bleaching powder has been used for bleaching paper pulps and fabrics and for sterilizing water. Its bleaching power arises from the formation, in the presence of air containing carbon dioxide, of the oxidizing agent chloric I acid hypochlorous acid, HClO : Ca ClO 2.
Ca OH 2. See tar. Angular momentum is thus quantized. In fact, Bohr in his theory did not use the wave behavior of the electron to derive this relationship. He assumed from the beginning that angular momentum was quantized in this way. Its experimental value is 1. The theory is named for the Danish physicist Niels Bohr — BOD See biochemical oxygen demand. A crystal structure in which the unit cell has an atom, ion, or molecule at each corner of a cube and at the center of the cube.
In this type of structure the coordination number is 8. It is less close-packed than the facecentered cubic structure. The alkali metals form crystals with body-centered cubic structures. Only a small number of atoms have ever been produced. Symbol: Bh; p. Bohr theory A theory introduced in to explain the spectrum of atomic hydrogen. If the electron is considered to have wave properties, then there must be a whole number of wavelengths around the orbit, otherwise the wave would be a progressive wave.
At this temperature the vapor pressure of the liquid is equal to the external pressure, and bubbles of vapor can form within the liquid. This temperature is always the same for a particular liquid at a given pressure for reference purposes usually taken as standard pressure. See also elevation of boiling point. A mixture of A and B at composition L1 would have a boiling point T1 and a vapor composition V1, which when condensed would give a liquid at L2.
L2 would boil at T2 to give vapor V2 equivalent to liquid of composition L3, and so on. Thus the whole process of either distillation or fractionation of this system will lead to progressive enrichment in component A. The separation of the curves as well as the difference in boiling points determines the performance of fractionation columns.
See also constant-boiling mixture. This formula is a quantitative expression of the idea that the entropy of a system is a measure of its disorder. It was discovered by Ludwig Boltzmann in the late 19th century in the course of his investigations into the foundations of statistical mechanics. A known amount of the substance is ignited inside the calorimeter in an atmosphere of pure oxygen, and undergoes complete combustion at constant volume. The resultant rise in temperature is related to the energy released by the reaction. Such energy values calorific values are often quoted in joules per kilogram J kg—1.
Temperature bond The interaction between atoms, V1 molecules, or ions holding these entities together. The forces giving rise to bonding may vary from extremely weak intermolecular forces, about 0. See bond energy; bond length; coordinate bond; covalent bond; electrovalent bond; hydrogen bond; metallic bond. Strictly speaking bond enthalpy should be used.
The bond dissociation energy is a different quantity to the bond energy. It is the energy required to break a particular bond in a compound, e. The constant is named for the Austrian theoretical physicist Ludwig Edward Boltzmann — See also degrees of freedom. Boltzmann formula A fundamental re- bond enthalpy See bond energy. BOND, the distance between the centers of the nuclei of two atoms joined by a chemical bond. Bond lengths may be measured by electron or x-ray diffraction.
A borax bead is formed by heating a little borax on a loop in a platinum wire.
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A minute sample is introduced into the bead and the color observed in both the oxidizing and reducing areas of a Bunsen-burner flame. The color is also noted when the bead is cold. Boric acid is used as a mild antiseptic eye lotion and was formerly used as a food preservative. It is used in glazes for enameled objects and is a constituent of Pyrex glass.
Trioxoboric III acid is the full systematic name for the solid acid and it exists in this form in its dilute solutions. See boron hydride. It has the electronic structure 1s22s22p1. Boron is of low abundance 0. High-purity boron for semiconductor applications is obtained by conversion to boron trichloride, which can be purified by distillation, then reduction using hydrogen. Only small quantities of elemental boron are needed commercially; the vast majority of boron supplied by the industry is in the form of borax or boric acid. Boron does not react directly with hydrogen to form boron hydrides boranes but the hydrolysis of magnesium boride does produce a range of boranes such as B4H10, B5H9, and B6H Thermal decomposition of these higher boranes produces, among other things, the simplest borane, B2H6 diborane.
The species BH3 is only a short-lived reaction intermediate. A number of polymeric species with B—B and B—O links are known, e. Although the parent acid is weak, many salts containing borate anions are known but their stoichiometry gives little indication of their structure, many of which are cyclic or linear polymers. These contain both BO3 planar groups and BO4 tetrahedra. Boric acid and the borates give a range of glassy substances on heating; these contain cross-linked B—O—B chains and nets. In the molten state these materials react with metal ions to form borates, which on cooling give characteristic colors to the glass.
See borax-bead test. The material has an extremely high melting point and is thermally very stable but there is sufficient bond polarity in the B—N links to permit slow hydrolysis by water to give ammonia. Boron halides are industrially important as catalysts or promoters in a variety of organic reactions including polymerization and Friedel—Crafts type alkylations. The decomposition of boron halides in atmospheres of hydrogen at elevated temperatures is also used to deposit traces of pure boron in semiconductor devices. Boron forms a range of compounds with elements that are less electronegative than itself, called borides.
Borides such as ZrB2 and TiB2 are hard refractory substances, which are chemically inert and have remarkably high electrical conductivities. Borides have a wide range of stoichiometries, from M4B through to MB6, and can exist in close-packed arrays, chains, and two-dimensional nets. Natural boron consists of two isotopes, 10B These percentages are sufficiently high for their detection by splitting of infrared absorption or by n.
Both borax and boric acid are used as mild antiseptics and are not regarded as toxic; boron hydrides are however highly toxic. Symbol: B; m.
These compounds are notable for containing B—H—B bonds. The compound B2H6 can be prepared by reacting boron trichloride with hydrogen. Other, more complex, borohydride ions exist. Feed enters the center of a shallow bowl, which contains revolving blades. The coarse solids collect on the bottom, fine solids at the periphery. It has two crystalline forms. The value of K depends on the temperature and on the nature of the gas. The law holds strictly only for ideal gases.
The law is named for the British chemist and physicist Robert Boyle — See gas laws. It forms various salts but also exhibits some amphoteric properties. See boron trichloride. Certain crystalline borosilicate minerals are known. In addition, borosilicate glasses can be made by using boron oxide in addition to silicon IV oxide.
The color of brass changes from red-gold to golden to silvery-white with increasing zinc content. Brasses are easy to work and resist corrosion well. It has been used to make hydrogen for the Haber process. The process is named for the German industrial chemist Carl Bosch — The properties of brass can be improved by the addition of other elements; lead improves its ability to be machined, while aluminum and tin increase its corrosion resistance.
See also bronze; nickel—silver. Industrial methods of production utilize oxidation by chlorine or electrolysis with removal from the solution by purging with air. Bromine and its compounds are used in pharmaceuticals, photography, chemical synthesis, fumigants, and in significantly large quantities as 1,2dibromoethane which is added to gasoline to combine with lead produced from the decomposition of the antiknock agent lead tetraethyl.
The electropositive elements form ionic bromides and the non-metals form fully covalent bromides. Like chlorine, bromine forms oxides, Br2O and BrO2, both of which are unstable. The related oxo-acid anions hypobromite BrO— and bromate BrO3— are formed by the reaction of bromine with cold aqueous alkali and hot aqueous alkali respectively, but the bromine analogs of chlorite and perchlorate are not known. Bromine and the interhalogens are highly toxic. Liquid bromine and bromine solutions are also very corrosive and goggles and gloves should always be worn when handling such compounds.
Symbol: Br; m. Brin process See barium. It has strong bleaching powers. Bromic I acid will donate protons to only a small extent and hence is a weak acid in aqueous solution. It is a strong oxidizing agent. See also bromine water. It dissociates extensively in aqueous solution and is a strong acid.
It is a very reactive compound, its reactions being similar to those of its component halides. It is a weak acid and a strong oxidizing agent, and decomposes to give a mixture of bromide Br— and bromate V BrO3— ions. Bromine is a liquid at room temperature mercury is the only other element with this property. It occurs in small amounts in seawater, salt lakes, and salt deposits but is much less abundant than chlorine. Bromine reacts with most metals but generally with less vigor than chlorine.
It has less oxidizing power than chlorine and consequently can be released from solutions of bromides by reaction with chlorine gas. It can be made from ethene and hydrogen bromide. It can be made from methane and bromine. The C60 polyhedron has a combination of pentagonal and hexagonal faces similar to the panels on a soccer ball. The molecule was named for the American architect Richard Buckminster Fuller — because its structure resembles a geodesic dome invented by Fuller.
The C60 polyhedra are informally called bucky balls. The original method of making the allotrope was to fire a high-power laser at a graphite target. This also produces less stable carbon clusters, such as C It can be produced more conveniently using an electric arc between graphite electrodes in an inert gas. The allotrope is soluble in benzene, from which it can be crystallized to give yellow crystals. This form of carbon is also known as fullerite. The discovery of buckminsterfullerene led to a considerable amount of research into its properties and compounds.
Particular interest has been shown in trapping metal ions inside the carbon cage to form enclosure compounds. Buckminsterfullerene itself is often simply called fullerene.
They are generally harder, stronger in compression, and more corrosion resistant than brass. The presence of lead improves its machining qualities. Some copper-rich alloys containing no tin are also called bronzes.
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Brownian movement Brownian motion The random motion of small particles in a fluid — for example, smoke particles in air. The particles, which may be large enough to be visible with a microscope, move because they are continuously bombarded by the molecules of the fluid. Brownian movement is named for the Scottish botanist Robert Brown — A freshly prepared solution of iron II sulfate is mixed with the sample and concentrated sulfuric acid is introduced slowly to the bottom of the tube using a dropping pipette so that two layers are formed. A brown ring formed where the liquids meet indicates the presence of nitrate.
The brown color is Buckminsterfullerene 44 butanoic acid Bunsen cell A type of primary cell in lar cluster e. Carbon structures similar to that in C60 can also form small tubes, known as bucky tubes. The buret is a long cylindrical graduated tube of uniform bore fitted with a stopcock and a small-bore exit jet, enabling a drop of liquid at a time to be added to a reaction vessel. Burets are widely used for titrations in volumetric analysis. Standard burets permit volume measurement to 0. Similar devices are used to introduce measured volumes of gas at regulated pressure in the investigation of gas reactions.
Buffer solutions generally contain a weak acid and one of its salts derived from a strong base; e. Phosphate, oxalate, tartrate, borate, and carbonate systems can also be used for buffer solutions. It is used in the manufacture of synthetic rubber. Buta-1,3-diene is conjugated and to some extent the pi electrons are delocalized over the whole of the molecule.
Gas is allowed into the bottom of the tube and the gas—air mixture is burnt at the top. With too little air the flame is yellow and sooty. The inner region is the reducing part of the flame and the outer region the oxidizing part see borax-bead test. The Bunsen burner is named for the German chemist Wilhelm Bunsen — He did not invent the Bunsen burner, but used it to great effect in pioneering work on spectroscopy. Butane is easily liquefied and its main use is as a portable supply of fuel bottle gas. Butane is the fourth member of the homologous series of alkanes.
It forms during the fermentation of sugar sucrose. Esters of butanoic acid are present in butter. Both are colorless volatile liquids used as solvents. It is manufactured by the oxidation of butane and used as a solvent. Transbutenedioic acid fumaric acid is a crystalline compound found in certain plants. Cisbutenedioic acid maleic acid is used in the manufacture of synthetic resins.
OH trans fumaric Butenedioic acids the inner surface of the tire.
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Other uses are in sealants, hoses, and pond liners. Before the introduction of tubeless tires butyl rubber was used for inner tubes because it is impervious to air. Subsequently halogenated butyl rubbers were developed halobutyls , which could be cured at higher temperature and vulcanized with other rubbers.
Both chlorobutyls and bromobutyls are manufactured. These types of rubber are used in tubeless tires bonded to by-product A substance obtained during the manufacture of a main chemical product. For example, propanone is not now manufactured from propanol, but is obtained as a by-product in the manufacture of phenol by the cumene process. Calcium chloride is a by-product of the Solvay process for making sodium carbonate. Some metals are obtained as by-products in processes to extract other metals. Cadmium, for instance, is a by-product of the extraction of zinc.
It is used to protect other metals from corrosion, as a neutron absorber in nuclear reactors, in alkali batteries, and in certain pigments. It is highly toxic. Symbol: Cd; m. The electronic configuration is that of argon with an additional pair of 4s electrons. However sufficiently large quantities of calcium chloride are available as waste from the Solvay process to satisfy industrial requirements for the metal, which is produced by electrolysis of the fused salt. Large quantities of lime, Ca OH 2, and quicklime, CaO, are produced by decomposition of the carbonate for use in both building and agriculture.
Several calcium minerals are mined as a source of other substances. Thus, limestone is a cheap source of carbon dioxide, gypsum and anhydrite are used in the manufacture of sulfuric acid, phosphate rock for phosphoric acid, and fluorspar for a range of fluorochemicals. Calcium has a low ionization potential and a relatively large atomic radius. It is therefore a very electropositive element. Both the oxide and the metal itself react with water to give the basic hydroxide Ca OH 2. On heating with nitrogen, sulfur, or the halogens, calcium reacts to form the nitride Ca3N2 , sulfide CaS , or the halides CaX2.
Cal- cadmium cell See Weston cadmium cell. A mineral consisting of hydrated zinc silicate 2ZnO. It is also known as hemimorphite. Zinc carbonate ZnCO3 , which occurs naturally as a mineral also known as smithsonite. The carbonate is used medicinally in suspension as a soothing lotion for sunburn and skin complaints. Formerly, the natural mineral was used for this but now medicinal calamine is made by precipitating a basic zinc carbonate from a solution of a zinc salt.
It is usually colored pink by the addition of small quantities of iron III oxide. Both the carbonate and sulfate are insoluble. Calcium salts impart a characteristic brick-red color to flames which is an aid to qualitative analysis. Symbol: Ca; m. These minerals make up the bulk of such rocks as marble, limestone, and chalk. Calcium carbonate also occurs in the mineral dolomite CaCO3. It is sparingly soluble in water but dissolves in rainwater containing carbon dioxide to form calcium hydrogencarbonate, which causes temporary hardness of water.
Calcium carbonate is a basic raw material in the Solvay process and is used for making glass, mortar, and cement. The solid is unknown at room temperature. See hardness. It is readily soluble in water and the solution, known as brine, is used in refrigerating plants. Other applications that depend on its water-absorbing property and the low freezing point of the aqueous solution include the suppression of dust on roads and in mines and the melting of snow.
Calcium chloride is used as the electrolyte in the production of calcium. Calcium hydroxide is manufactured by adding water to the oxide, a process known as slaking, which evolves much heat. If just sufficient water is added so that the oxide turns to a fine powder, the product is slaked lime. If more water is added, a thick suspension called milk of lime is formed. It is used as a fertil48 calomel electrode component of the slag produced in smelting iron and other metals in a blast furnace. As a base, it is used to neutralize acid soil and in industrial processes such as the Solvay process.
It is also used in the manufacture of mortar, whitewash, and bleaching powder and for the softening of temporary hard water. When heated, gypsum loses water to form the hemihydrate 2CaSO4. H2O , which is plaster of Paris. If the water is replaced, gypsum reforms and sets as a solid. Plaster of Paris is therefore used for taking casts and for setting broken limbs. Calcium sulfate is sparingly soluble in water and is a cause of permanent hardness in water. It is used in ceramics, paint, and in paper making.