Abstract Spectroscopy is a leading technique in studying internal constitution, structure, and isotope shift of atoms, ions, and molecules. Atoms and ions usually do emit light when exposed to high amounts of heat which makes such spectra lines visible under spectroscope, clearly showing differences between various energy levels present in an atom. The aim of the experiment was to document spectroscope design and how such can be used to observe visible spectra lines of gaseous atoms namely the noble gases and hydrogen. The methods used included using a helium discharge tube to calibrate the spectroscope in order to locate the spectra lines relative to the reference line. The results showed that Hydrogen had the lowest number of visible spectra lines while Xenon had the highest. This was attributed to the number of energy levels in these atoms. Key words: spectra lines, spectroscopy, photon, energy levels Introduction Analytical atomic spectrometry consists of numerous techniques on distinct principles and characteristics. Spectroscopy primarily entails studying the internal constitution of atoms, ions, and molecules including the hyperfine structure and isotope shift. On the other hand, spectra chemistry entails determining wavelengths with high degree of accuracy due to the sharpness of the spectra frequencies emitted by free particles. Usually, all atoms and ions emit light when exposed to high temperatures thus when observed on a spectroscope, a series of colored lines characteristic of the differences between various energy levels are observed. This practical report details an experiment in which a simple spectroscope is developed to observe spectra lines in atoms and thus provide basis for qualitative analysis. Materials A grafting film, source of light, spectrophotometer, prism or diffraction grafting, and elements (H, Ne, Kr, Ar, Xe, He) Methodology A cigar or a cake box of at least one inch in depth was fitted with slots, one inch deep and ¼ inch wide,...
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33. Elements differ according to the number of protons their atoms contain, a value called the element's atomic number. All atoms of a given element have the same number of protons and an equal number of electrons. The number of neutrons in an atom is not predictable but is generally as great or greater than the number of protons. The total number of protons plus neutrons in an atom is called the atom's mass number. 40. Protons, electrons, and neutrons. Protons, neutrons (1 amu) and electrons 5 x 10-4. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. 41. The protons and neutrons are packed inside the nucleus and the electrons are outside of the nucleus forming an electron cloud. 43. (a) Phosphorus P (b) Niobium Nb (c) Cobalt Co 45. (a) protons = 13, electrons = 13, neutrons = 14 (b) protons = 14, electrons = 14, neutrons = 14 (c) protons = 5, electrons = 5., neutrons = 6 (d) protons = 47, electrons = 47, neutrons = 68 46. C 49. (a) 122 (b) 136 (c) 118 (d) 48 51. (a) Neon (Ne) (b) Vanadium (V) (c) Iron (Fe) 54. 60. (a) Metals (b) Transition metal element (c) 3d 62. Selenium 66. Each orbital can hold only TWO electrons, which must be of opposite spin. 70. There are 10 electrons that are present in this atom. This element is NEON. 71. There are 14 electrons that are present in this atom. This element is SILICON. 73. (a) (b) (c) (d) 75. Four because the group numbers from 1A through 8A give the numbers of valence electrons for the elements in each main group. 77. Group 6A 79. 83. The stars underwent a gravitational collapse resulting in the synthesis of elements heavier than iron. 84. (a) ultraviolet (b) Gamma waves (c) X-rays 85.Ultraviolet rays have a higher concentrated energy than visible light, which makes their wavelength shorter and more powerful....
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Water is vital for life, with out water life on earth would cease to exist as every living organism must have water in order to survive. The total amount of water on Earth is fixed, (75% of the earth is covered in water) and most is recycled and re-used. The largest reservoirs are oceans and open seas. Very little is actually contained within living organisms, although water is a major constitute of most life forms. Water is a major component of cells, typically forming between 70 and 95% of the mass of the cell. Therefore humans are made from approximately 80% water by mass as opposed to some soft bodied, aquatic creatures such as jellyfish are made of up to 96% water. Water also provides an environment for organisms to live in. this is why when space probes are dispatched to other planets in search of life they look for the presence of water to determine if life is possible there. Water itself is a simple chemical compound, each molecule composed of 2 hydrogen atoms and one oxygen atom: H O. The hydrogen and oxygen atoms are bonded covalently. Water is not a linear molecule; the two hydrogen atoms form a bond with the oxygen at the angle of 104.5. Covalent bonds are formed by sharing electrons in the outer orbits of the electron cloud. However, in water the large numbers of protons in the oxygen nucleus have a stronger attraction for these shared electrons than the comparatively tiny hydrogen nuclei. This pulls the electrons slightly closer to the oxygen nucleus and away from the hydrogen so that the oxygen develops a slight negative charge and the hydrogen a slight positive charge. This makes the molecules strongly dipolar. This charge means that when water molecules are close together the positively charged hydrogen...
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Aluminum, symbol Al, the most abundant metallic element in the earth\'s crust. The atomic number of aluminum is 13; the element is in group 13 (IIIa) of the periodic table. Hans Christian Orstead, Danish chemist, first isolated aluminum in 1825, using a chemical process involving potassium amalgam. Between 1827 and 1845, Friedrich Wöhler, a German chemist, improved Oersted\'s process by using metallic potassium. He was the first to measure the specific gravity of aluminum and show its lightness. In 1854 Henri Sainte-Claire Deville, in France, obtained the metal by reducing aluminum chloride with sodium. Aided by the financial backing of Napoleon III, Deville established a large-scale experimental plant and displayed pure aluminum at the Paris Exposition of 1855. Aluminum is a lightweight, silvery metal. The atomic weight of aluminum is 26.9815; the element melts at 660° C (1220° F), boils at 2467° C (4473° F), and has a specific gravity of 2.7. Aluminum is a strongly electropositive metal and extremely reactive. In contact with air, aluminum rapidly becomes covered with a tough, transparent layer of aluminum oxide that resists further corrosive action. For this reason, materials made of aluminum do not tarnish or rust. The metal reduces many other metallic compounds to their base metals. For example, when thermite (a mixture of powdered iron oxide and aluminum) is heated, the aluminum rapidly removes the oxygen from the iron; the heat of the reaction is sufficient to melt the iron. This phenomenon is used in the thermite process for welding iron . The oxide of aluminum is amphoteric—showing both acidic and basic properties. The most important compounds include the oxide, hydroxide, sulfate, and mixed sulfate compounds. Anhydrous aluminum chloride is important in the oil and synthetic-chemical industries. Many gemstones—ruby and sapphire, for example—consist mainly of crystalline aluminum oxide. Aluminum is the most abundant metallic constituent...
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Hello my fellow readers. My name is Silver. My name comes from the Anglo-Saxon word of Siolfur. Some people call me Ag for short (Ag stands argentum.) I am a white shinny metal. Since I am a white shinny metal argentum is the Latin word for white and shinning. I live in the periodic table of elements and my address is 47. I usually weigh 107.868. I am solid at room temperature. Copper and gold are my good friends and they make me strong and help me to be more durable. You can find me almost anywhere. You can find me pure in silver ores and you can find me in structure forms in kitchens, jewelry stores, car shops, doctor offices, dentist offices, banks, and even in wallets. I am a very valuable metal. But although you can find me most anywhere, only 16% of me is used in coins and jewelry, while 40% is used to make photographic film. The rest of me is used in industries and health services. I am even used to make mirrors. I am only slightly reactive and because of this I am placed very close to the bottom of the reactivity chart. I have very little uses in chemistry because of my low reactivity status. I don't form oxides when I touch air but I do form silver sulfide when I touch polluted air. I form a tarnish when I interact with the hydrogen sulfide in the air, especially near industrial cities. The result of this is that I turn to silver sulfide. Tarnish is a dark, brown, or black film that develops slowly on me. Some silver tableware can tarnish because some food that you eat contains hydrogen sulfide. Hard boiled eggs are the perfect example of hydrogen sulfide. You can also sometimes see...
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This article mainly talks about how combinatorial synthesis or chemistry is being used in the drug industry today. The article starts with how combinatorial synthesis began. It said it started in the early 1990s as an ambition of revolutionizing drug discovery. The rest of the article mainly talks about how they screen for highly complex mixtures, mixtures of equivocal mixtures. Then they move on to talk about screening of the interior of resin beads and then the screening of mircoarrays. This article says that if bridging the gap between combinatorial synthesis and bioassays is important if combinatorial chemistry is to achieve is ambitious goal of supplying efficient methods for the selection of biologically active molecules."(Direct from article). This article had some good and some bad points throughout it. The main problem with the article is that it was really hard to understand. They used a lot of terms that as the reader, I would not know. This article also seemed very technical, saying that this, this and this did this. Not much was on what is combinatorial synthesis. This article was probably intended for those who know about this stuff already. But why then start with something that would sound like some who has never know about this before what to find out more about it. This article was brief too; it sped through things really quick and ended pretty quickly too. It should have flowed so the reader could read it more easily. Fairley, Peter. (1998). Combinatorial Chemistry. Chemical Week, 150, 18 In the article Combinatorial Chemistry they basically talk about what it is. The article says that it is a "the rapid synthesis of thousands or millions of chemical com-pounds." It says that combinatorial chemistry has revolutionized the drug industry discovery process. The company R&D wonders what this experimentation could do...
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Anhydrous Ammonia is a very distinctive and important compound. Some call it a harmless fertilizer which farmers use to help grow and fertilize crops. Other may call it destructive or dangerous to the environment; in other words, a threat. Causing water pollution by toxic fluids running off into coastal waters and into storm drains and air pollution releasing toxins into the air while producing this deadly chemical, anhydrous ammonia been called many things. Anhydrous ammonia is a man-made product used for fertilizer, nitric acid production, refrigeration, disinfectant, fuel and cigarettes. It must be handled carefully by trained professionals and stored in a high-pressured environment using special equipment. Anhydrous Ammonia is also called Ammonia and Ammonium Hydroxide. There are many ways to make Anhydrous Ammonia; one of them being from the urine in our bodies, which is an acid and can be made into any sort of ammonia. It is made by using temperature, pressure and sometimes catalysts. It is one part nitrogen and three parts hydrogen. Anhydrous Ammonia is one of the most dangerous chemicals that can be used on the farm. Anhydrous Ammonia is a low cost and readily available fertilizer, but the danger and consequences are far worse than the lack of it. Ammonia is a colorless, pungent gas, NH3, extensively used to manufacture fertilizers and a wide variety of nitrogen-containing organic and inorganic chemicals. It is the most familiar compound composed of the elements nitrogen and hydrogen. It is formed as a result of the decomposition of most nitrogenous organic material, and its presence is indicated by it pungent and irritating odor. It has a wide range of agricultural and industrial applications. It is used for the production of nitric acid and ammonium salts, particularly the sulfate, nitrate, carbonate, and chloride, and the synthesis of hundreds of organic compounds including...
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Silicon is one of man's most useful elements. In the form of sand and clay it is used to make concrete and brick; it is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc. Silica, as sand, is a principal ingredient of glass, one of the most inexpensive of materials with excellent mechanical, optical, thermal and electrical properties. Hyperpure silicon can be doped with boron, gallium, phosphorus, or arsenic to produce silicon for use in transistors, solar cells, rectifiers, and other solid-state devices, which are used extensively in the electronics and space-age industries. Though silicon was originally discovered in 1810 and thought to be a compound silicon was discovered as an element in 1823 by Jons Berzelius. In 1824 Berzelius prepared amorphous silicon by the same general method and purified the product by removing the fluosilicates by repeated washings. Deville in 1854 first prepared crystalline silicon, the second allotropic form of the element. Davy in1800 thought silica to be a compound and not an element; later in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride. Silicon is a metalloid at room temperature with an atomic number of 14, 14 electrons, 14 neutrons, and an average atomic mass of 28.0855. In its pure form,silicon melts at 2,570 degrees, and boils at 4,271 degrees Fahrenheit. This element belongs to the metalloid family, the 14th family on the periodic table of elements. This element is a solid metalloid at room temperature and turns to liquid at 2,570 degrees. Silicon is prepared as a brown amorphous powder or as gray-black crystals. Crystalline silicon has a metallic luster and grayish color. It is hard, non-magnetic, and most acids do not effect it, but it does dissolve in...
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Joseph Black was best known for his discovery and chemical activity of carbon dioxide. Black was born in Bordeaux, France, and went to school at the universities of Glasgow and Edinburgh in Scotland. He was professor of chemistry, medicine, and anatomy at the University of Glasgow from 1756 to 1766. He became a professor of chemistry at the University of Edinburgh. In about 1761 Black discovered latent heat, and three years later he measured the latent heat of steam. His student and assistant James Watt then put the discoveries to use when he made improvements to the steam engine. About 1754 Black discovered carbon dioxide, a gas which he called "fixed air", and showed its function in the causticization of lime or in other words making lime more alkaline, and helping to disprove the phlogiston theory of combustion. He also discovered that different substances have different heat capacities. Joseph Black discovered carbon dioxide by using experiments that involves the first gravimetric measurements on changes brought about when heating magnesia alba and reacting the products with acids or alkalis in 1754. He discovered carbon dioxide to help disprove the phlogiston theory of combustion and he showed that there are other gases in the air besides just air, which made the people realize that carbon dioxide was important for the world as well as other gasses. Carbon dioxide is important to both the U.S. and the world because without Co2 life on earth would most likely not be present without it. Because of the fact that plant life needs Co2 to breathe, we need the oxygen created through photosynthesis from the plants to survive ourselves. In this, Joseph Black can be known as a worldwide hero to chemistry history. People now understand the importance of carbon dioxide and how it affects the atmosphere today....
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A captain of a ship drunkenly crashes a massive oil tanker along a reef and changes the physical and emotional world forever. Chemical spills are major problems that plague the environment. Strict government regulation is trying to aid with this problem, but governmental leaders face many challenges. Disposal of harmful chemicals is often difficult and costly. Since chemical waste has destroyed the environment, steps are being taken to prevent further pollution. A local Danish based pharmaceutical company named Novo Nordisk released its 1999 environmental report. The company, which strives to keep from contaminating the environment, confessed to two separate accidents for the year. Novo Nordisk's Clayton, North Carolina plant was fined from the United States Department of Agriculture 1,000 dollars. This was due to the fact that 11,000 liters of hydrochloric acid was disposed of in the public sewage system ("Putting Values" 36). New management has taken action to insure this does not happen again (Wall). Also, at the Gentofte site in Denmark wastewater with the E- Coli bacteria was drained into the public sewage system from a leaky heater exchanger ("Putting Values" 36). The incident was reported to the local authorities and cleaned up quickly. A local company offered to donate expired chemicals to local schools. The company reported it would be possible to set up an account for almost any needy school (Wall). The chemicals have expired in the date in which they can be used but, as one expert reported would be fine to use in schools for experiments and related activities. The companies prefer to donate the chemicals because it keeps them from the costly action of disposing of them properly. For example Novo Nordisk in Clayton, North Carolina has a program in which they donate hydrochloric acid and other expired chemicals to Clayton High School (Wall). A...
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Editorial: Liquid asset One third of the world's population already lives in water-scarce areas. And stocks of water are dwindling: not only because a burgeoning population needs to quench its thirst, but also to meet increasing agricultural demands for crop growth. Add to that the water demands of low-carbon alternatives to fossil fuels, including biofuels and hydrogen (see Chemistry World , May 2008, p12), and industry's insatiable appetite for water, and it's clear demand is rapidly overwhelming supply. Many predict that the major conflicts of the coming century will be fought over water. And the unpredictable impacts of climate change mean that we cannot simply rely on surface water resources to continue to be replenished by rain. Time to compromise The issue is not just quantity, it's quality. Urban pressure on water supplies means more and more people are quite literally tapping the same sources - and also that water treatment has to cope with a swathe of previously undiscovered pollutants (see p48). Many of these, including active pharmaceuticals, simply slip through traditional water treatment systems. More advanced purification systems are already in existence that are capable of removing almost all of them, but at what cost? There are questions to be answered about the impact of new pollutants before money is spent on removing them. Only the best scientific advice will aid the development of good water management, which, in some cases is going to prove very expensive indeed. There will often be simpler solutions: it cannot be sensible for people in many developed countries to continue to use high quality, drinkable water to flush toilets and water lawns while more than one in six people throughout the world have no access at all to safe, clean drinking water. The scientific community must play a key role in deciding in which direction the money...
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Grasslands emit greenhouse gas 20 August 2008 Chinese researchers have found further evidence that plants emit significant quantities of methane - a potent greenhouse gas. But the latest findings also show that methane emissions depend not just on the species of plant, but the conditions in which they are growing. Frank Keppler, from the Max Planck Institute for Nuclear Physics, Heidelberg, Germany, first claimed in January 2006 that the world's plants, previously seen as a greenhouse gas sink thanks to their CO2 uptake, actually emit millions of tons of methane. As a greenhouse gas, methane is 20 times more potent than CO2. While a contentious finding, subsequent studies have confirmed that plants could emit the greenhouse gas - but that emissions are species-dependent. In November 2007, Zhi-Ping Wang of the Chinese Academy of Science, Beijing, and colleagues revealed the methane emissions of 44 species of plants from the temperate grasslands of Inner Mongolia. While none of the 35 herbaceous species tested seemed to produce methane, seven out of nine shrub species did emit the gas. However, the latest study, by Xingliang Xu of the Chinese Academy of Science in Xining and coworkers, apparently contradicts that finding. Studying an area of Tibetan alpine meadow, Xu found that shrub species took in methane from the atmosphere, while two species of herbaceous grass were emitters of the gas, contributing significantly to the regional methane levels. But Keppler says he disagrees that the studies are contradictory, and points to the different natural environments in which the plants were growing. 'This just shows how complex living plant systems are,' Keppler told Chemistry World. 'We now know that, depending on the plant species, but also on environmental conditions and stress factors, you can get different rates of emission.' Keppler is currently examining the mechanism by which plants might be producing methane - and...
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Gold's magic number 20 August 2008 A new gold catalyst developed by UK chemists can catalyze hydrocarbon oxidation, using O2 as the only oxidant. But catalyst particle size is critical - above 2nm diameter, the catalyst loses all activity. The catalyst was developed by Richard Lambert and colleagues at the University of Cambridge, who used styrene oxidation as a test reaction. The team found that the reaction didn't require any additional oxidants such as peroxides. Oxygen molecules adsorbed to the gold particles, and then dissociated to give single oxygen atoms that initiated the styrene oxidation. 'Styrene is a very good test molecule which can be handled easily,' says Marc Armbrüster, who also works at the University of Cambridge and collaborates with the group. Oxygenated hydrocarbons are also valuable intermediates for industry. 'The prospect of selective oxidation using molecular oxygen without the addition of additives over a new catalyst is exciting,' comments Jeroen van Bokhoven, from the Institute for Chemical and Bioengineering at ETH Zurich, Switzerland. 'There seems to be space for trying the catalyst out on more systems and for improving the selectivity,' van Bokhoven adds. The catalyst consists of 55-atom gold clusters, which form nanometer-sized particles on inert supports. The Au55 particles are so-called 'magic number' clusters that contain exactly the right number of atoms for very stable geometries, making them ideally suited to catalysis. However, the particle size of the catalyst is critical. While 1.4nm diameter particles were effective and robust catalysts, particles 2nm or larger have no catalytic activity. The researchers used x-ray photoelectron spectroscopy to show that the nano-clusters have a different electronic structure to bulk gold. 'As the particles become smaller, their electronic structure changes significantly,' explains Armbrüster. The organic reactant only weakly adsorbs to the catalyst, so that its electronic structure is not perturbed. 'We don't know exactly how the catalyst...
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Aim: The aim of this investigation is to investigate the rate of reaction of magnesium (mg) with Hydrochloric acid (HCl). After studying the availability of equipment I have chosen to investigate how concentration can affect the rate of reaction. Other variables that affect this investigation are: - Concentration of solution - Temperature - Surface area of a solid - Catalyst - Light - Pressure of a gas Prediction: I predict that when changing the concentration of hydrochloric acid and water, the slower the rate of reaction will be. I think this because when observing a previous experiment, it showed the less Hydrochloric acid and the more water used in a test tube, the rate of reaction is slow. Scientific knowledge: To help me gain better knowledge about the investigation I have found out some scientific information relating to the experiment of 'rates and reaction'. The main areas I have covered are concentration of solution, temperature and catalyst. After researching my scientific evidence I have found out that depending on collisions in particles will depend on the reaction being faster or slower. This happens if the reacting particles collide with each other, or there is sufficient energy in the collision to overcome the activation energy. Concentration To increase the rate of reaction, the concentration of the reaction needs to increase this is by the Hydrogen and magnesium ribbon being added to the solution of Hydrochloric acid. The following reaction occurs: Temperature If temperature is increased the rate of reaction also increase. This is by the chemical particles receiving kinetic energy. If more kinetic energy is present in the particles, the particles move faster, this also means the particles will be colliding with each other often. Catalysts A catalyst is a substance that changes the rate of reaction but remains unchanged itself therefore it is an element that changes the rate of a chemical reaction without being used up. For example,...
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Originally two German chemists named Wurtz, in 1848, and Hentschel, in 1884 made the first Isocyanates, one of the building blocks of Polyurethane. Originally polyurethane was developed for military use by Otto Bayer, in the late 1930's, and was the first to make polyurethane commercially available. Molecular Structure Polyurethane is a polymer that consists of repeating units [__ROOCNH__R'__]n. 'R' can represent a different alkyl group, which is obtained by removing a hydrogen atom from a hydrocarbon. Polyurethane's are mostly thermoset plastics meaning the resins cross-link and cannot be melted and remolded. Some polyurethane's are Linear Aliphatic Polyurethane which are thermoplastics. This means the resins are linear and do not cross-link, subsequently they can be reprocessed. Thermoplastic polyurethane is not only linear but has highly crystalline structures. It is because of this that it forms an abrasion resistant material. The diagram above shows the molecular structure of complex polyurethane. Complex polyurethane is considered this because it is made from an isocyanate base. This type of urethane is created through the reaction between an isocyanate and a polyol (Alcohol). Types There are many different types of polyurethane's to include the following: rigid foams, flexible foams, adhesives, sealants, coatings, cast elastomers, and spandex fibers. All polyurethane's have one thing in common: they contain urethane linkages formed by the chemical reaction between the isocyanate and the polyol. These various forms make polyurethane a very versatile plastic in liquid and solid form. Applications Rigid foams or hard foams are used as insulation for buildings, water heaters, refrigeration, and floatation devices. Flexible foams or soft, open-celled polyurethane foams are used as cushion padding under carpets, furniture cushioning, mattresses, and packaging material. Adhesives and sealants are used where high strength, moisture resistance and durability is needed such as construction, automotive and marine applications. Mainly in the automotive field you will see polyurethane as...
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Titanium was discovered in 1791 in the mineral menachanite by the British clergyman William Gregor, who named the new element menachite. Four years later, the German chemist Martin Heinruch Klaproth rediscovered the element in the mineral rutile and named it titanium in allusion to the strength of the mythological Greek Titans. The metal was isolated in 1910. The element is present in meteorites and the sun. It is used in many things that enhance everyday life such as fashion apparel, medical equipment, automobiles, architecture, aerospace, marine technology, industrial tools, as well as sports equipment. Titanium has played a main role in helping to not only conserve, but to improve our economy. Because of its strength and light weight, Titanium is used in metallic alloys and as a substitute for aluminum. It is used in aircrafts for the fire walls, outer skin, landing- gear components, hydraulic tubing , and engine supports. Space capsules and missiles are also largely made with titanium , and were used immensely when making the Mercury, Gemini, and Apollo capsules. The relative inertness of titanium makes it available as a replacement for bone and cartilage in surgery and as a pipe and tank lining in the processing of foods that we eat. It is used in heat exchangers in desalinization plants because of its ability to withstand saltwater corrosion. Titanium dioxide, which is commonly known as titanium white, is a brilliant white pigment used in paints, lacquers, paper, plastics, textiles, and rubber. Titanium is the fourth most abundant metals in the earth's crust. The capacity for production substantially exceeds long term forecast of demand. Product prices are low and stable. Titanium and rutile ore both sourced in friendly countries with stable regimes, unlike nickel or chromium, and so the price of titanium has never really been subject to crisis...
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This essay talks about Iodine. What it does to the body when there is deficiency and toxicity. Why it is important to the body. The essay focuses on different age groups as well. The precautions to take. etc. If you are looking for a grade 12 study report on Iodine deficiency and toxicity then this is for you! A human body has to intake iodine (which is found in food as iodide) for the proper functioning of thyroid glands related hormones. These hormones are called: thyroxine and tri-iodothyronine - and they are synthesized from the amino acid tyrosine and from iodide. The two hormones are essential for the body mainly because they regulate metabolic rate and promote growth and development throughout the body including the brain. In the case where there is a deficiency of thyroid hormones in the blood, the thyroid gland will become enlarged which is known as goiter. This deficiency occurs when they thyroid gland does not have enough iodine to make the hormones thyroxine and tri-iodothyronine. Due to the increase of cell size to get more iodine it causes a swelling in the neck when the size of the whole gland increases. Besides from causing in goiter, the deficiency of iodine may also lead to dry skin, hair loss, fatigue, and slowed reflexes. In the developing of a fetus and young child, iodine deficiency in more serious. Stunned growth, diminished intelligence, and retardation may result from the deficiency of iodine in the new born. Vegetarians can be said to be another group that may be at risk of iodine deficiency because they do not eat seafood. However, they receive their iodine from iodized table salt, or seaweeds. Hypothyroidism is another deficiency that occurs when the thyroid gland cannot manufacture enough thyroid hormone because the immune system produces...
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Determination of a Chemical Formula Introduction: This lab will show us how we can use acid-base titration to find molecular formulas of compounds. Specifically, we will be working with Zinc, Calcium, Hydrochloric Acid, and Water. Data: Calculations: See notebook tear-out under "Calculations" heading Discussion: The purpose of this lab was to observe the reactions of metals with water and acid. We used Zinc and Calcium specifically. As I expected, the Calcium samples were more reactive to both water and hydrochloric acid. I determined this based on its location on the periodic table and the knowledge that the column of metals, of which Calcium is a part of, is highly reactive. When my lab partner and I lit the match and held it to the mouth of the test tube it went out. There was no explanation in the lab manual of why this occurs, but I am guessing that it has to do with the reaction between carbon monoxide and gases produced by the reactions in the test tube. Or, maybe the reactions were drawing oxygen into the tube, which would remove the source of fuel for the match burning. One source of error would be if in part 2 the calcium did not fully react with water before titrating the solution with HCl. This would cause a lack of Ca(OH)2 thereby throwing all calculations. Also, if the molarity of the HCl being used to titrate was not correct, the results would not be accurate because molarity is required to calculate information such as moles of hydrogen ions. This lab demonstrated to me how titration really works and gave me a better understanding of the reactions between acids and bases, and between metals and water/acids....
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Acid-Base Equilibria: Determination of Acid Ionization Constants Introduction: The purpose of this lab is to learn about acid ionization constants and buffer solutions. We will be determining the acid ionization constant by finding pH with pH meters. In part three we will prepare a buffer solution and then observe the change in pH as either an acid or base is added. Data: Discussion: The majority of this experiment was focused on determination of Ka, or the acid ionization constant. To find Ka we were given concentrations of each chemical in the solution and its concentration individually. We then determined the pH, and solved using an ICE table. In part 1, we found the half equivalence point by titrating HA with NaOH, plotting the graph with excel, and then visually finding the halfway mark. The pH at this point was 4.26, which tells us that Ka = 5.50 x 10-5 by knowing pH = pKa and Ka = 10-pKa at the half equivalency point. This means that HA has very little dissociation in an aqueous solution, which is expected because it is a weak acid. In part 2, we were yet again attempting to find the disassociation constant of acetic acid in different solutions by knowing volume, concentration and pH. We found three very different constants, an error which will be covered later. Actually completing these steps was very elementary and does not need to be discussed. Part 3 was the second half of this lab. We created a buffer solution using 30mL each of 1.0M NaA and HA, and the pH was recorded. We then divvied this into two beakers. 2mL 1.0M HCl was added to one and 2mL 1.0M NaOH was added to the other. The pH level was recorded for each of these solutions. The original buffer solution had a pH of 4.49. Solution 1 with...
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Summary: Aluminum and steel were tested over three different temperature readings. One of each sample was put into an oven at about 245°F, a bath of ice water and finally in dry ice at about -30°F. After the metal sample's temperature was changed by exposure to each external stimulus, we proceeded to break each sample. The Impact Test Machine was used to break the steel sample. The CIM-24 was used to break the aluminum sample. Procedure: The pendulum was raised up to the top position just prior to doing the test. After the sample was exposed to the different stimulus for about 15 minutes, the samples were placed into the machine. When the arm was released, the specimen was broken and the amount of force was determined from the equation: Absorbed Energy in Ft. Lbs. = 11.85 + 12.03 * COS (è) where è is the observed angle on the dial. Error analysis: The cause of errors could have been from human error or faulty equipment. Human error could have been a factor when the steel was being placed into the machine, when the machine was being set-up, or when the data was being read off of the machine. The faulty equipment could be if any tools we used in this machine were not calibrated. Conclusions: The experiment involved taking two different kinds of metals and showing through data and graphical analysis, a useful temperature range for both metals. In this experiment however, only one sample of each metal was exposed to each different temperature, due to the lack of time, yielding inaccurate results. With the lack of collected data, the tabulated data and graphical analysis can only show the limited results....
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