1.
Melting point
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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, melting 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 also 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
2.
Natural dye
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Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources—roots, berries, bark, leaves, archaeologists have found evidence of textile dyeing dating back to the Neolithic period. In China, dyeing with plants, barks and insects has been traced more than 5,000 years. The essential process of dyeing changed little over time, typically, the dye material is put in a pot of water and then the textiles to be dyed are added to the pot, which is heated and stirred until the color is transferred. Textile fibre may be dyed before spinning, but most textiles are yarn-dyed or piece-dyed after weaving, many mordants, and some dyes themselves, produce strong odors, and large-scale dyeworks were often isolated in their own districts. Plant-based dyes such as woad, indigo, saffron, and madder were raised commercially and were important trade goods in the economies of Asia, across Asia and Africa, patterned fabrics were produced using resist dyeing techniques to control the absorption of color in piece-dyed cloth. Dyes such as cochineal and logwood were brought to Europe by the Spanish treasure fleets, the discovery of man-made synthetic dyes in the mid-19th century triggered a long decline in the large-scale market for natural dyes. Natural dyeing techniques are preserved by artisans in traditional cultures around the world. In the early 21st century, the market for natural dyes in the industry is experiencing a resurgence. Western consumers have become concerned about the health and environmental impact of synthetic dyes in manufacturing. The European Union, for example, has encouraged Indonesian batik cloth producers to switch to natural dyes to improve their market in Europe. Protein fibres require vat, acid, or indirect/mordant dyes, that require a bonding agent, each synthetic fibre requires its own dyeing method, for example, nylon requires acid, disperse and pigment dyes, rayon acetate requires disperse dyes, and so on. The earliest surviving evidence of textile dyeing was found at the large Neolithic settlement at Çatalhöyük in southern Anatolia, polychrome or multicolored fabrics seem to have been developed in the 3rd or 2nd millennium BCE. Textiles with a warp and an ochre-yellow weft were discovered in Egyptian pyramids of the Sixth Dynasty. His contributions to refining the process and his theories on colour brought much praise by the well known poet. Some dyestuffs, such as indigo and lichens, will give good color when used alone, the majority of plant dyes, however, also require the use of a mordant, a chemical used to fix the color in the textile fibres. These dyes are called adjective dyes, by using different mordants, dyers can often obtain a variety of colors and shades from the same dye. Fibres or cloth may be pretreated with mordants, or the mordant may be incorporated in the dyebath, salt helps to fix or increase fastness of colors, vinegar improves reds and purples, and the ammonia in stale urine assists in the fermentation of indigo dyes
3.
Hydrogen
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Hydrogen is a chemical element with chemical symbol H and atomic number 1. With a standard weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form is the most abundant chemical substance in the Universe, non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton, the universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays an important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a charge when it is known as a hydride. The hydrogen cation is written as though composed of a bare proton, Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Industrial production is mainly from steam reforming natural gas, and less often from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market, Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen gas is flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol,2 H2 + O2 →2 H2O +572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%, the explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C, the detection of a burning hydrogen leak may require a flame detector, such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames, the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. The visible orange flames in that incident were the result of a mixture of hydrogen to oxygen combined with carbon compounds from the airship skin. H2 reacts with every oxidizing element, the ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, however, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity. The most complicated treatments allow for the effects of special relativity
4.
Crystal
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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, diamonds, 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, rocks, ceramics, a third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever. Examples of amorphous solids include glass, wax, and many plastics, Crystals are often used in pseudoscientific practices such as crystal therapy, and, 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, ceramics, ice, rocks, solids that are neither crystalline nor polycrystalline, such as glass, are called amorphous solids, also 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
5.
Cotton
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Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus Gossypium in the family of Malvaceae. The fiber is almost pure cellulose, under natural conditions, the cotton bolls will tend to increase the dispersal of the seeds. The plant is a native to tropical and subtropical regions around the world, including the Americas, Africa. The greatest diversity of wild species is found in Mexico, followed by Australia. Cotton was independently domesticated in the Old and New Worlds, the fiber is most often spun into yarn or thread and used to make a soft, breathable textile. Current estimates for world production are about 25 million tonnes or 110 million bales annually, China is the worlds largest producer of cotton, but most of this is used domestically. The United States has been the largest exporter for many years, in the United States, cotton is usually measured in bales, which measure approximately 0.48 cubic meters and weigh 226.8 kilograms. Cotton cultivation in the region is dated to the Indus Valley Civilization, the Indus cotton industry was well-developed and some methods used in cotton spinning and fabrication continued to be used until the industrialization of India. Between 2000 and 1000 BC cotton became widespread across much of India, for example, it has been found at the site of Hallus in Karnataka dating from around 1000 BC. Cotton fabrics discovered in a cave near Tehuacán, Mexico have been dated to around 5800 BC, the domestication of Gossypium hirsutum in Mexico is dated between 3400 and 2300 BC. Cotton was grown upriver, made into nets, and traded with fishing villages along the coast for supplies of fish. The Spanish who came to Mexico and Peru in the early 16th century found the people growing cotton and this may be a reference to tree cotton, Gossypium arboreum, which is a native of the Indian subcontinent. According to the Columbia Encyclopedia, Cotton has been spun, woven and it clothed the people of ancient India, Egypt, and China. Hundreds of years before the Christian era, cotton textiles were woven in India with matchless skill, in Iran, the history of cotton dates back to the Achaemenid era, however, there are few sources about the planting of cotton in pre-Islamic Iran. The planting of cotton was common in Merv, Ray and Pars of Iran, in Persian poets poems, especially Ferdowsis Shahname, there are references to cotton. Marco Polo refers to the products of Persia, including cotton. John Chardin, a French traveler of the 17th century who visited the Safavid Persia, during the Han dynasty, cotton was grown by Chinese peoples in the southern Chinese province of Yunnan. Mohamed Ali Pasha accepted the proposition and granted himself the monopoly on the sale and export of cotton in Egypt, and later dictated cotton should be grown in preference to other crops
6.
Lithium-ion battery
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A lithium-ion battery or Li-ion battery is a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, the electrolyte, which allows for ionic movement, and the two electrodes are the constituent components of a lithium-ion battery cell. Lithium-ion batteries are common in home electronics and they are one of the most popular types of rechargeable batteries for portable electronics, with a high energy density, tiny memory effect and low self-discharge. Beyond consumer electronics, LIBs are also growing in popularity for military, battery electric vehicle, for example, lithium-ion batteries are becoming a common replacement for the lead–acid batteries that have been used historically for golf carts and utility vehicles. Chemistry, performance, cost and safety characteristics vary across LIB types, handheld electronics mostly use LIBs based on lithium cobalt oxide, which offers high energy density, but presents safety risks, especially when damaged. Lithium iron phosphate, lithium ion manganese oxide battery and lithium nickel manganese cobalt oxide offer lower energy density, such batteries are widely used for electric tools, medical equipment and other roles. NMC in particular is a contender for automotive applications. Lithium nickel cobalt aluminum oxide and lithium titanate are specialty designs aimed at particular niche roles, the newer lithium–sulfur batteries promise the highest performance-to-weight ratio. Lithium-ion batteries can pose unique safety hazards since they contain a flammable electrolyte, an expert notes If a battery cell is charged too quickly, it can cause a short circuit, leading to explosions and fires. Because of these risks, testing standards are more stringent than those for acid-electrolyte batteries, there have been battery-related recalls by some companies, including the 2016 Samsung Note 7 recall for battery fires. This article covers just the topics and general principles of lithium-ion batteries. Nearly all facets have elements that are impacted by currently very active development or research, a cell is a basic electrochemical unit that contains the basic components, such as electrodes, separator, and electrolyte. In the case of cells, this is the single cylindrical, prismatic or pouch unit. In this regard, the simplest battery is a cell with perhaps a small electronic circuit for protection. In many cases, distinguishing between cell and battery is not important, however, this should be done when dealing with specific applications, for example, battery electric vehicles, where battery may indicate a high voltage system of 400 V, and not a single cell. The term module is used as an intermediate topology, with the understanding that a battery pack is made of modules. In electrochemistry, the anode is the electrode where oxidation is taking place in the battery, i. e. electrons get free, however, this happens on opposite electrodes during charge vs. discharge. Historically, for lithium cells, which started as single use discharge cells and this is true on discharge, but with a rechargeable system, the negative electrode chemically becomes the cathode while charging
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