Miscibility
Miscibility /mɪsᵻˈbɪlᵻti/ is the property of substances to mix in all proportions, forming a homogeneous solution. The term is most often applied to liquids, but applies to solids and ethanol, for example, are miscible because they mix in all proportions. By contrast, substances are said to be if a significant proportion does not form a solution. Otherwise, the substances are considered miscible, for example, butanone is significantly soluble in water, but these two solvents are not miscible because they are not soluble in all proportions. In organic compounds, the percent of hydrocarbon chain often determines the compounds miscibility with water. For example, among the alcohols, ethanol has two atoms and is miscible with water, whereas 1-octanol with eight carbons is not. Octanols immiscibility leads it to be used as a standard for partition equilibria and this is the case with lipids, the very long carbon chains of lipids cause them almost always to be immiscible with water. Analogous situations occur for other functional groups, acetic acid is miscible with water, whereas valeric acid is not.
Immiscible metals are unable to form alloys with each other, typically, a mixture will be possible in the molten state, but upon freezing the metals separate into layers. This property allows solid precipitates to be formed by freezing a molten mixture of immiscible metals. One example of immiscibility in metals is copper and cobalt, where rapid freezing to form solid precipitates has been used to create granular GMR materials, there exist metals that are immiscible in the liquid state. One with industrial importance is that liquid zinc and liquid silver are immiscible in liquid lead and this leads to the Parkes process, an example of liquid-liquid extraction, whereby lead containing any amount of silver is melted with zinc. The silver migrates to the zinc, which is skimmed off the top of the liquid. Substances with extremely low configurational entropy, especially polymers, are likely to be immiscible in one even in the liquid state. Miscibility of two materials is often determined optically, when the two miscible liquids are combined, the resulting liquid is clear.
If the mixture is cloudy the two materials are immiscible, care must be taken with this determination. If the indices of refraction of the two materials are similar, an immiscible mixture may be clear and give an incorrect determination that the two liquids are miscible, miscibility gap Emulsion Heteroazeotrope ITIES Multiphasic liquid
Electrolyte
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent, such a solution is neutral. The movement of anions and cations in opposite directions within the solution amounts to a current and this includes most soluble salts and bases. Some gases, such as chloride, under conditions of high temperature or low pressure can function as electrolytes. Electrolyte solutions can result from the dissolution of some biological and synthetic polymers, termed polyelectrolytes, a substance that dissociates into ions in solution acquires the capacity to conduct electricity. Sodium, chloride, calcium and phosphate are examples of electrolytes, in medicine, electrolyte replacement is needed when a patient has prolonged vomiting or diarrhea, and as a response to strenuous athletic activity. Commercial electrolyte solutions are available, particularly for children and athletes.
Electrolyte monitoring is important in the treatment of anorexia and bulimia, the word electrolyte derives from the Greek lytós, meaning able to be untied or loosened. Arrheniuss explanation was that in forming a solution, the salt dissociates into charged particles, faradays belief had been that ions were produced in the process of electrolysis. Arrhenius proposed that, even in the absence of an electric current and he thus proposed that chemical reactions in solution were reactions between ions. For example, carbon dioxide gas dissolves in water to produce a solution that contains hydronium, molten salts can be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. An electrolyte in a solution may be described as concentrated if it has a concentration of ions. If a high proportion of the solute dissociates to form ions, the electrolyte is strong, if most of the solute does not dissociate. The properties of electrolytes may be exploited using electrolysis to extract constituent elements, in physiology, the primary ions of electrolytes are sodium, calcium, chloride, hydrogen phosphate, and hydrogen carbonate.
The electric charge symbols of plus and minus indicate that the substance is ionic in nature and has a distribution of electrons. Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte, all known higher lifeforms require a subtle and complex electrolyte balance between the intracellular and extracellular environments. In particular, the maintenance of precise osmotic gradients of electrolytes is important, such gradients affect and regulate the hydration of the body as well as blood pH, and are critical for nerve and muscle function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control, both muscle tissue and neurons are considered electric tissues of the body
Gold
Gold is a chemical element with symbol Au and atomic number 79. In its purest form, it is a bright, slightly yellow, soft, malleable. Chemically, gold is a metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions, Gold often occurs in free elemental form, as nuggets or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the element silver and naturally alloyed with copper. Less commonly, it occurs in minerals as gold compounds, often with tellurium, golds atomic number of 79 makes it one of the higher numbered, naturally occurring elements. It is thought to have produced in supernova nucleosynthesis, from the collision of neutron stars. Because the Earth was molten when it was formed, almost all of the present in the early Earth probably sank into the planetary core. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of acid and hydrochloric acid. Gold dissolves in solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys, but this is not a chemical reaction, as a precious metal, gold has been used for coinage and other arts throughout recorded history. A total of 186,700 tonnes of gold is in existence above ground, the world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold is used in infrared shielding, colored-glass production, gold leafing, certain gold salts are still used as anti-inflammatories in medicine. As of 2014, the worlds largest gold producer by far was China with 450 tonnes, Gold is cognate with similar words in many Germanic languages, deriving via Proto-Germanic *gulþą from Proto-Indo-European *ǵʰelh₃-. The symbol Au is from the Latin, the Latin word for gold, the Proto-Indo-European ancestor of aurum was *h₂é-h₂us-o-, meaning glow. This word is derived from the root as *h₂éu̯sōs, the ancestor of the Latin word Aurora. This etymological relationship is presumably behind the frequent claim in scientific publications that aurum meant shining dawn, Gold is the most malleable of all metals, a single gram can be beaten into a sheet of 1 square meter, and an avoirdupois ounce into 300 square feet.
Gold leaf can be thin enough to become semi-transparent
Chloroplatinic acid
Chloroplatinic acid or hexachloroplatinic acid is an inorganic compound with the formula 2x. A red solid, it is an important commercial source of platinum, although often written in shorthand as H2PtCl6, it is the hydronium salt of the hexachloroplatinate anion. The compound is available as the hexahydrate. Chloroplatinic acid is produced by dissolving platinum metal sponge in aqua regia, brownish red crystals can be isolated by evaporating this solution to a syrup. Pt +4 HNO3 +6 HCl → H2PtCl6 +4 NO2 +4 H2O A related procedure gives the hexahydrate, alternative methods have been heavily investigated, but the older literature can be unreliable. When heated, hexachloroplatinic acid decomposes first to platinum chloride, 2PtCl6·nH2O → PtCl4 +2 HCl + H2O Chloroplatinic acid was popularized for the determination of potassium. The potassium is selectively precipitated as potassium chloroplatinate, determinations were done in 85% alcohol solutions with excess platinate ions, and the precipitated product was weighed.
Potassium could be detected for solutions as dilute as 0.02 to 0. 2% and this method for determination of potassium was advantageous vs. the sodium cobaltinitrite method used previously, since it required a single precipitation reaction. Today, the concentration of potassium is determined with an ion-selective electrode and these modern methods remain subject to interference. Treatment with a salt, such as ammonium chloride, precipitates solid ammonium hexachloroplatinate. Heating the ammonium salt in hydrogen reduces it to elemental platinum, platinum is often isolated from ores or recycled from residues thus. Like many platinum compounds, chloroplatinic acid is used in catalysis and this compound was first reported by John Speier and colleagues from Dow Corning Corporation to catalyze the addition of silyl hydrides to olefins, hydrosilylation. Early test reactions used isopropanol solutions of trichlorosilane with pentenes, prior work on the addition of silanes to alkenes required radical reactions that were inefficient.
As well as with Karstedts catalyst, Speiers catalyst enjoys widespread use for hydrosilylation and it is generally agreed that chloroplatinic acid is a precursor to the actual catalyst. A possible role for colloidal platinum or zero-valent complexes has been considered, Chloroplatinic acid prepared from aqua regia is occasionally contaminated with nitrosonium hexachloroplatinate, 2PtCl6. This species is obtained by the reaction of chloride and platinum metal
Chemical milling
Chemical milling or industrial etching is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. It is mostly used on metals, though materials are increasingly important. It was developed from armor-decorating and printing etching processes developed during the Renaissance as alternatives to engraving on metal, most modern chemical milling methods involve alkaline etchants, these may have been used as early as the first century CE. Armor etching, using mineral acids, was not developed until the fifteenth century. Etchants mixed from salt and vinegar were applied to plate armor that had painted with a maskant of linseed-oil paint. The etchant would bite into the areas, causing the painted areas to be raised into relief. Not long after, it used to etch trajectory information plates for cannon and artillery operators, paper would rarely survive the rigors of combat. Often such information was etched onto equipment such as daggers or shovels.
In 1782, the discovery was made by John Senebier that certain resins lost their solubility to turpentine when exposed to light, photo-chemical milling was extensively used in the development of photography methods, allowing light to create impressions on metal plates. Etching has applications in the circuit board and semiconductor fabrication industries. It is used in the industry to remove shallow layers of material from large aircraft components, missile skin panels. Etching is used widely to manufacture integrated circuits and Microelectromechanical systems, in addition to the standard, liquid-based techniques, the semiconductor industry commonly uses plasma etching. Chemical milling is normally performed in a series of five steps, masking, etching, cleaning is the preparatory process of ensuring that the surface to be etched is free of contaminants which could negatively impact the quality of the finished part. An improperly cleaned surface could result in poor adhesion of the maskant, causing areas to be etched erroneously, the surface must be kept free from oils, primer coatings and other residue from the marking out process and any other foreign contaminants.
For most metals, this step can be performed by applying a solvent substance to the surface to be etched, the material may be immersed in alkaline cleaners or specialized de-oxidizing solutions. It is common practice in modern industrial chemical etching facilities that the workpiece never be directly handled after this process, masking is the process of applying the maskant material to the surface to ensure that only desired areas are etched. Liquid maskants may be applied via dip-masking, in which the part is dipped into a tank of maskant. Maskant may be applied by flow coating, liquid maskant is flowed over the surface of the part, certain conductive maskants may be applied by electrostatic deposition, where electrical charges are applied to particles of maskant as it is sprayed onto the surface of the material
Jmol
Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development.
While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Google Chrome and Scriptable Molecular Graphics in Web Browsers without Java3D
Analytical chemistry
Analytical chemistry studies and uses instruments and methods used to separate and quantify matter. In practice separation, identification or quantification may constitute the entire analysis or be combined with another method, qualitative analysis identifies analytes, while quantitative analysis determines the numerical amount or concentration. Analytical chemistry consists of classical, wet chemical methods and modern, classical qualitative methods use separations such as precipitation and distillation. Identification may be based on differences in color, melting point, boiling point, classical quantitative analysis uses mass or volume changes to quantify amount. Instrumental methods may be used to separate samples using chromatography, electrophoresis or field flow fractionation and quantitative analysis can be performed, often with the same instrument and may use light interaction, heat interaction, electric fields or magnetic fields. Often the same instrument can separate and quantify an analyte, Analytical chemistry is focused on improvements in experimental design and the creation of new measurement tools.
Analytical chemistry has applications to forensics, science. Analytical chemistry has been important since the days of chemistry, providing methods for determining which elements. The first instrumental analysis was flame emissive spectrometry developed by Robert Bunsen, most of the major developments in analytical chemistry take place after 1900. During this period instrumental analysis becomes progressively dominant in the field, in particular many of the basic spectroscopic and spectrometric techniques were discovered in the early 20th century and refined in the late 20th century. The separation sciences follow a similar line of development and become increasingly transformed into high performance instruments. In the 1970s many of these began to be used together as hybrid techniques to achieve a complete characterization of samples. Lasers have been used in chemistry as probes and even to initiate. Modern analytical chemistry is dominated by instrumental analysis, many analytical chemists focus on a single type of instrument.
Academics tend to focus on new applications and discoveries or on new methods of analysis. The discovery of a present in blood that increases the risk of cancer would be a discovery that an analytical chemist might be involved in. An effort to develop a new method might involve the use of a laser to increase the specificity and sensitivity of a spectrometric method. Many methods, once developed, are kept purposely static so that data can be compared over long periods of time and this is particularly true in industrial quality assurance and environmental applications
Melting point
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
Osmium
Osmium is a chemical element with symbol Os and atomic number 76. It is a hard, bluish-white transition metal in the group that is found as a trace element in alloys. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3, Osmium has a blue-gray tint and is the densest stable element, approximately twice the density of lead and slightly denser than iridium. Calculations of density from the X-ray diffraction data may produce the most reliable data for these elements, Osmium is a hard but brittle metal that remains lustrous even at high temperatures. It has a very low compressibility, its bulk modulus is extremely high, reported between 395 and 462 GPa, which rivals that of diamond. The hardness of osmium is moderately high at 4 GPa, because of its hardness, low vapor pressure, and very high melting point, solid osmium is difficult to machine, form, or work. Osmium forms compounds with oxidation states ranging from −2 to +8, the most common oxidation states are +2, +3, +4, and +8.
The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridiums +9 and is encountered only in xenon, ruthenium and iridium. The oxidation states −1 and −2 represented by the two reactive compounds Na 2 and Na 2 are used in the synthesis of osmium cluster compounds, the most common compound exhibiting the +8 oxidation state is osmium tetroxide. This toxic compound is formed when powdered osmium is exposed to air and it is a very volatile, water-soluble, pale yellow, crystalline solid with a strong smell. Osmium powder has the smell of osmium tetroxide. Osmium tetroxide forms red osmates OsO 42−2 upon reaction with a base, with ammonia, it forms the nitrido-osmates OsO 3N−. Osmium tetroxide boils at 130 °C and is an oxidizing agent. By contrast, osmium dioxide is black, non-volatile, and much less reactive, Osmium pentafluoride is known, but osmium trifluoride has not yet been synthesized. The lower oxidation states are stabilized by the halogens, so that the trichloride, triiodide.
The oxidation state +1 is known only for osmium iodide, whereas several carbonyl complexes of osmium, such as triosmium dodecacarbonyl, in general, the lower oxidation states of osmium are stabilized by ligands that are good σ-donors and π-acceptors. The higher oxidation states are stabilized by strong σ- and π-donors, such as O2−, despite its broad range of compounds in numerous oxidation states, osmium in bulk form at ordinary temperatures and pressures resists attack by all acids and alkalis, including aqua regia. Osmium has seven naturally occurring isotopes, six of which are stable, 184Os, 187Os, 188Os, 189Os, 190Os, and 192Os
Density
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
Laboratory glassware
Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories. There are several types of glass, each used for different purposes, borosilicate glass, which is commonly used in reagent bottles, can withstand thermal stress. Quartz glass, which is common in cuvettes, can withstand high temperatures and is transparent in parts of the electromagnetic spectrum. Darkened brown or amber glass, which is common in dark storage bottles, can block ultraviolet, heavy-wall glass, which is common in glass pressure reactors, can withstand pressurized applications. There are many different kinds of laboratory glassware items and these include, Examples of glassware containers include, Beakers are simple cylindrical shaped containers used to hold reagents or samples. Flasks are narrow-necked glass containers, typically conical or spherical, used in a laboratory to hold reagents or samples, Examples flasks include the Erlenmeyer flasks and Florence flasks.
Bottles are containers with narrow openings generally used to store reagents or samples, jars are cylindrical containers with wide openings that may be sealed. Bell jars are used to contain vacuums, watch glasses are shallow glass dishes used as an evaporating surface or to cover a beaker. Glass evaporating dishes are used to evaporate materials, microscope slides are thin strips used to hold items under a microscope. Glass petri dishes are used to living cells. Examples of glassware used for include, Graduated cylinders are cylindrical containers used for volumetric measurements. Burettes are used to precise amounts of liquid reagents. Glass pipettes are used to transfer precise quantities of fluids, Glass Ebulliometers are used to accurately measure the boiling point of liquids. Other examples of glassware includes, Glass tubes are cylindrical pieces of glassware used to hold or transport fluids, stirring rods are used to mix chemicals. Funnels are used to get materials through a narrow opening, condensers are used to cool hot liquids or vapors.
Glass retorts are used for distillation, drying pistols are used to free samples from traces of water, or other impurities. Most laboratory glassware is currently mass-produced, but large laboratories may employ a blower to construct specialized pieces. This construction forms a field of glassblowing requiring precise control of shape
