1.
Potassium bromide
Potassium bromide is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the US. Its action is due to the bromide ion, potassium bromide is used as a veterinary drug, as an antiepileptic medication for dogs. Under standard conditions, potassium bromide is a crystalline powder. It is freely soluble in water, it is not soluble in acetonitrile, in a dilute aqueous solution, potassium bromide tastes sweet, at higher concentrations it tastes bitter, and tastes salty when the concentration is even higher. These effects are due to the properties of the potassium ion—sodium bromide tastes salty at any concentration. In high concentration, potassium bromide strongly irritates the mucous membrane, causing nausea. Potassium bromide, an ionic salt, is fully dissociated. It serves as a source of bromide ions, bromide can be regarded as the first effective medication for epilepsy. At the time, it was thought that epilepsy was caused by masturbation.
Locock noted that bromide calmed sexual excitement and thought this was responsible for his success in treating seizures, there was not a better epilepsy drug until phenobarbital in 1912. Bromides exceedingly long life in the body made it difficult to dose without side effects. Medical use of bromides in the US was discontinued at this time, as many better, use of bromide in cats is limited because it carries a substantial risk of causing lung inflammation in them. Potassium bromide is not approved by the US Food and Drug Administration for use in humans to control seizures, in Germany, it is still approved as an antiepileptic drug for humans, particularly children and adolescents. These indications include severe forms of generalized tonic-clonic seizures, early-childhood-related Grand-Mal-seizures, adults who have reacted positively to the drug during childhood/adolescence may continue treatment. Potassium bromide tablets are sold under the brand name Dibro-Be mono, the drug has almost complete bioavailability, but the bromide ion has a relatively long half life of 12 days in the blood, making bromide salts difficult to adjust and dose.
The therapeutic index for bromide is small, as with other antiepileptics, sometimes even therapeutic doses may give rise to intoxication. Often indistinguishable from expected side-effects, these include, Bromism These are central nervous system reactions, tongue disorder, bad breath, and obstipation occur. Potassium bromide is transparent from the ultraviolet to long-wave infrared wavelengths and has no significant optical absorption lines in its high transmission region
2.
Silver
Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays.
Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm.
The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
3.
Silver(I) fluoride
Silver fluoride is the inorganic compound with the formula AgF. It is one of the three main fluorides of silver, the others being silver subfluoride and silver fluoride, AgF has relatively few niche applications, it has been employed as a fluorination and desilylation reagent in organic synthesis and in aqueous solution as a topical caries treatment in dentistry. The hydrates of AgF present as colourless, while pure anhydrous samples are yellow, ag2O + 2HF →2 AgF + H2O The structure of AgF has been determined by X-ray diffraction. At ambient temperature and pressure, silver fluoride exists as the polymorph AgF-I, the rock salt structure adopted by the other silver monohalides. The lattice parameter is 4.936 Å, significantly lower than those of AgCl and AgBr. Neutron and X-ray diffraction studies have shown that at 2.70 GPa, a structural transition occurs to a second polymorph with the caesium chloride structure. The associated decrease in volume is approximately ten percent, a third polymorph, AgF-III, forms on reducing the pressure to 2.59 GPa, and has an inverse nickel arsenide structure.
The lattice parameters are a =3.244 Å and c =6.24 Å, non-stochiometric behaviour is exhibited by all three polymorphs under extreme pressures. Silver fluoride exhibits unusual optical properties, the fundamental exciton for AgF lies at 4.63 eV. This discrepancy can be explained by positing transition from a band with largely silver 4d-orbital character. The high frequency refractive index is 1.73, in contrast with the other silver halides, anhydrous silver fluoride is not appreciably photosensitive, although the dihydrate is. Unlike the other halides, AgF is highly soluble in water. It is unique among silver compounds and the silver halides in that it forms the hydrates AgF.2, like the alkali metal fluorides, it dissolves in hydrogen fluoride to give a conducting solution. Silver fluoride finds application in chemistry for addition of fluoride across multiple bonds. For example, AgF adds to perfluoroalkenes in acetonitrile to give perfluoroalkylsilver derivatives and it can be used as a desulfuration-fluorination reagent on thiourea derived substrates.
Due to its solubility in water and organic solvents, it is a convenient source of fluoride ions. Tetralkylammonium fluorides can be prepared in the laboratory by the reaction of the tetralkylammonium bromide with an aqueous AgF solution. It is possible to coat a surface with a uniform silver microlayer by passing AgF vapour over it at 60–800 °C
4.
Aqueous solution
An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant chemical formula, for example, a solution of table salt, or sodium chloride, in water would be represented as Na+ + Cl−. The word aqueous means pertaining to, related to, similar to, as water is an excellent solvent and is naturally abundant, it is a ubiquitous solvent in chemistry. Substances that are hydrophobic often do not dissolve well in water, an example of a hydrophilic substance is sodium chloride. Acids and bases are aqueous solutions, as part of their Arrhenius definitions, the ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves. If the substance lacks the ability to dissolve in water the molecules form a precipitate, reactions in aqueous solutions are usually metathesis reactions. Metathesis reactions are another term for double-displacement, that is, when a cation displaces to form a bond with the other anion.
The cation bonded with the latter anion will dissociate and bond with the other anion, aqueous solutions that conduct electric current efficiently contain strong electrolytes, while ones that conduct poorly are considered to have weak electrolytes. Those strong electrolytes are substances that are ionized in water. Nonelectrolytes are substances that dissolve in water yet maintain their molecular integrity, examples include sugar, urea and methylsulfonylmethane. When writing the equations of reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility, soluble compounds are aqueous, while insoluble compounds are the precipitate. Remember that there may not always be a precipitate, when performing calculations regarding the reacting of one or more aqueous solutions, in general one must know the concentration, or molarity, of the aqueous solutions. Solution concentration is given in terms of the form of the prior to it dissolving.
Metal ions in aqueous solution Solubility Dissociation Acid-base reaction theories Properties of water Zumdahl S.1997, 4th ed. Boston, Houghton Mifflin Company
5.
Acid
An acid is a molecule or ion capable of donating a hydron, or, capable of forming a covalent bond with an electron pair. The first category of acids is the donors or Brønsted acids. In the special case of solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents, acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals to form salts. The word acid is derived from the Latin acidus/acēre meaning sour, an aqueous solution of an acid has a pH less than 7 and is colloquially referred to as acid, while the strict definition refers only to the solute. A lower pH means a higher acidity, and thus a higher concentration of hydrogen ions in the solution. Chemicals or substances having the property of an acid are said to be acidic, common aqueous acids include hydrochloric acid, acetic acid, sulfuric acid, and citric acid. As these examples show, acids can be solutions or pure substances, strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.
The second category of acids are Lewis acids, which form a covalent bond with an electron pair, hydrogen chloride, acetic acid, and most other Brønsted-Lowry acids cannot form a covalent bond with an electron pair and are therefore not Lewis acids. Conversely, many Lewis acids are not Arrhenius or Brønsted-Lowry acids, in modern terminology, an acid is implicitly a Brønsted acid and not a Lewis acid, since chemists almost always refer to a Lewis acid explicitly as a Lewis acid. Modern definitions are concerned with the chemical reactions common to all acids. Most acids encountered in life are aqueous solutions, or can be dissolved in water, so the Arrhenius. The Brønsted-Lowry definition is the most widely used definition, unless otherwise specified, hydronium ions are acids according to all three definitions. Interestingly, although alcohols and amines can be Brønsted-Lowry acids, they can function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms. The Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen ions or protons in 1884, an Arrhenius acid is a substance that, when added to water, increases the concentration of H+ ions in the water.
Thus, an Arrhenius acid can be described as a substance that increases the concentration of ions when added to water. Examples include molecular substances such as HCl and acetic acid, an Arrhenius base, on the other hand, is a substance which increases the concentration of hydroxide ions when dissolved in water. Thus, an Arrhenius acid could be said to be one that decreases hydroxide concentration, in an acidic solution, the concentration of hydronium ions is greater than 10−7 moles per liter
6.
Chemical compound
A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds. Many chemical compounds have a numerical identifier assigned by the Chemical Abstracts Service. For example, water is composed of two atoms bonded to one oxygen atom, the chemical formula is H2O. A compound can be converted to a different chemical composition by interaction with a chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the compounds, and bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as AB + CD → AC + BD, where A, B, C, and D are each unique atoms, and AB, CD, AC, and BD are each unique compounds. A chemical element bonded to a chemical element is not a chemical compound since only one element. Examples are the diatomic hydrogen and the polyatomic molecule sulfur. Chemical compounds have a unique and defined chemical structure held together in a spatial arrangement by chemical bonds.
Pure chemical elements are not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms. There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. Characteristic properties of compounds include that elements in a compound are present in a definite proportion, for example, the molecule of the compound water is composed of hydrogen and oxygen in a ratio of 2,1. In addition, compounds have a set of properties. The physical and chemical properties of compounds differ from those of their constituent elements, mixtures can be created by mechanical means alone, but a compound can be created only by a chemical reaction. Some mixtures are so combined that they have some properties similar to compounds.
Other examples of compound-like mixtures include intermetallic compounds and solutions of metals in a liquid form of ammonia. Compounds may be described using formulas in various formats, for compounds that exist as molecules, the formula for the molecular unit is shown. For polymeric materials, such as minerals and many metal oxides, the elements in a chemical formula are normally listed in a specific order, called the Hill system
7.
Ammonium carbonate
Ammonium carbonate is a salt with the chemical formula 2CO3. Since it readily degrades to ammonia and carbon dioxide upon heating, it is used as a leavening agent. It is known as ammonia and was a predecessor to the more modern leavening agents baking soda. It is a component of what was known as sal volatile. Ammonium carbonate is produced by combining carbon dioxide and aqueous ammonia, about 7000 tons/year were produced as of 1997. Ammonium carbonate slowly decomposes at standard temperature and pressure through two pathways, thus any initially pure sample of ammonium carbonate will soon become a mixture including various byproducts. It serves as an acidity regulator and has the E number E503 and it can be replaced with baking powder, but this may affect both the taste and texture of the finished product. Mr. Accum, in his Treatise on Culinary Poisons, has stigmatized this process as fraudulent, Ammonium carbonate is the main component of smelling salts, although the commercial scale of their production is small.
Buckleys cough syrup from Canada today uses ammonium carbonate as an active ingredient intended to relieve symptoms of bronchitis. It is used as an emetic and it is found in smokeless tobacco products, such as Skoal. It is used in solution as a photographic lens cleaning agent. Sal ammoniac, the form of ammonium chloride Ammonium nitrate Ammonium bicarbonate
8.
Ion
An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions.
Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge.
A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
9.
Crystal
A crystal or crystalline solid is a solid material whose constituents are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, the scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification, the word crystal derives from the Ancient Greek word κρύσταλλος, meaning both ice and rock crystal, from κρύος, icy cold, frost. Examples of large crystals include snowflakes and table salt, most inorganic solids are not crystals but polycrystals, i. e. many microscopic crystals fused together into a single solid. Examples of polycrystals include most metals, ceramics, a third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever. Examples of amorphous solids include glass and many plastics, Crystals are often used in pseudoscientific practices such as crystal therapy, along with gemstones, are sometimes associated with spellwork in Wiccan beliefs and related religious movements.
The scientific definition of a crystal is based on the arrangement of atoms inside it. A crystal is a solid where the form a periodic arrangement. For example, when liquid water starts freezing, the change begins with small ice crystals that grow until they fuse. Most macroscopic inorganic solids are polycrystalline, including almost all metals, ice, solids that are neither crystalline nor polycrystalline, such as glass, are called amorphous solids, called glassy, vitreous, or noncrystalline. These have no periodic order, even microscopically, there are distinct differences between crystalline solids and amorphous solids, most notably, the process of forming a glass does not release the latent heat of fusion, but forming a crystal does. A crystal structure is characterized by its cell, a small imaginary box containing one or more atoms in a specific spatial arrangement. The unit cells are stacked in three-dimensional space to form the crystal, the symmetry of a crystal is constrained by the requirement that the unit cells stack perfectly with no gaps.
There are 219 possible crystal symmetries, called space groups. These are grouped into 7 crystal systems, such as cubic crystal system or hexagonal crystal system, Crystals are commonly recognized by their shape, consisting of flat faces with sharp angles. Euhedral crystals are those with obvious, well-formed flat faces, anhedral crystals do not, usually because the crystal is one grain in a polycrystalline solid. The flat faces of a crystal are oriented in a specific way relative to the underlying atomic arrangement of the crystal. This occurs because some surface orientations are more stable than others, as a crystal grows, new atoms attach easily to the rougher and less stable parts of the surface, but less easily to the flat, stable surfaces
10.
Solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. The solubility of a substance depends on the physical and chemical properties of the solute and solvent as well as on temperature, pressure. The solubility of a substance is a different property from the rate of solution. Most often, the solvent is a liquid, which can be a substance or a mixture. One may speak of solid solution, but rarely of solution in a gas, the extent of solubility ranges widely, from infinitely soluble such as ethanol in water, to poorly soluble, such as silver chloride in water. The term insoluble is often applied to poorly or very poorly soluble compounds, a common threshold to describe something as insoluble is less than 0.1 g per 100 mL of solvent. Under certain conditions, the solubility can be exceeded to give a so-called supersaturated solution. Metastability of crystals can lead to apparent differences in the amount of a chemical that dissolves depending on its form or particle size. A supersaturated solution generally crystallises when seed crystals are introduced and rapid equilibration occurs, phenylsalicylate is one such simple observable substance when fully melted and cooled below its fusion point.
Solubility is not to be confused with the ability to dissolve a substance, for example, zinc dissolves in hydrochloric acid as a result of a chemical reaction releasing hydrogen gas in a displacement reaction. The zinc ions are soluble in the acid, the smaller a particle is, the faster it dissolves although there are many factors to add to this generalization. Crucially solubility applies to all areas of chemistry, inorganic, organic, in all cases it will depend on the physical conditions and the enthalpy and entropy directly relating to the solvents and solutes concerned. By far the most common solvent in chemistry is water which is a solvent for most ionic compounds as well as a range of organic substances. This is a factor in acidity/alkalinity and much environmental and geochemical work. According to the IUPAC definition, solubility is the composition of a saturated solution expressed as a proportion of a designated solute in a designated solvent. Solubility may be stated in units of concentration such as molarity, mole fraction, mole ratio, mass per volume.
Solubility occurs under dynamic equilibrium, which means that solubility results from the simultaneous and opposing processes of dissolution, the solubility equilibrium occurs when the two processes proceed at a constant rate. The term solubility is used in some fields where the solute is altered by solvolysis
11.
Chlorine
Chlorine is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the table and its properties are mostly intermediate between them. Chlorine is a gas at room temperature. It is an extremely reactive element and a strong oxidising agent, among the elements, it has the highest electron affinity, the most common compound of chlorine, sodium chloride, has been known since ancient times. Around 1630, chlorine gas was first synthesised in a chemical reaction, Carl Wilhelm Scheele wrote a description of chlorine gas in 1774, supposing it to be an oxide of a new element. In 1809, chemists suggested that the gas might be an element, and this was confirmed by Sir Humphry Davy in 1810. Because of its reactivity, all chlorine in the Earths crust is in the form of ionic chloride compounds. It is the second-most abundant halogen and twenty-first most abundant chemical element in Earths crust and these crustal deposits are nevertheless dwarfed by the huge reserves of chloride in seawater.
Elemental chlorine is produced from brine by electrolysis. The high oxidising potential of chlorine led to the development of commercial bleaches and disinfectants. As a common disinfectant, elemental chlorine and chlorine-generating compounds are used directly in swimming pools to keep them clean. Elemental chlorine at high concentrations is extremely dangerous and poisonous for all living organisms, in the form of chloride ions, chlorine is necessary to all known species of life. Other types of compounds are rare in living organisms. In the upper atmosphere, chlorine-containing organic molecules such as chlorofluorocarbons have been implicated in ozone depletion, small quantities of elemental chlorine are generated by oxidation of chloride to hypochlorite in neutrophils as part of the immune response against bacteria. Its importance in food was very well known in antiquity and was sometimes used as payment for services for Roman generals. Around 1630, chlorine was recognized as a gas by the Flemish chemist, the element was first studied in detail in 1774 by Swedish chemist Carl Wilhelm Scheele, and he is credited with the discovery.
He called it dephlogisticated muriatic acid air since it is a gas and he failed to establish chlorine as an element, mistakenly thinking that it was the oxide obtained from the hydrochloric acid. He named the new element within this oxide as muriaticum, in 1809, Joseph Louis Gay-Lussac and Louis-Jacques Thénard tried to decompose dephlogisticated muriatic acid air by reacting it with charcoal to release the free element muriaticum
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