The ZnO crystallizes in a few forms which are wurtzite, zinc blende and rocksalt as shown in Figure 2.4. The wurtzite structure is the most thermodynamically stable phase under ambient temperature and also very common. The zinc blende ZnO geometry can be stabilized only by growth on cubic lattice substrates and the rocksalt structure (NaCl structure) can be obtained at relatively high pressures using ultrasonic wave velocity measurements of up to 10 GPa. (Morkoc).
It occurs naturally as the mineral zincite, but most zinc oxide is produced synthetically (Marcel). Zinc oxide have an array of nanostructures, such as nanorods, nanotubes, nanorings and nanotetrapods (Varadan et. al).
ZnO is a relatively soft material. Compared to Group III nitrides, the elastic
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Commercial zinc oxide shows a measurable but low level of water solubility, 0.005 g/litre. Zinc oxide is amphoteric, that is it reacts with both acids and alkalis. With acid it reacts to form familiar compound such as zinc sulfate. With alkali it forms zincates. Zinc oxide exposed to air absorbs both water vapor and carbon dioxide. This results in the formation of basic zinc carbonate.
Zinc oxide also undergoes solid state reactions (calcination) at moderately elevated temperatures. Under electron microscopic examination, commercial zinc oxide frequently shows groups of particles that are conjoined, rather than loosely agglomerated. Zinc oxide calcines with other oxides such as silica and magnesia.
2.3.5 Potential and emerging applications of zinc oxide
Because of its diverse properties, both chemical and physical, zinc oxide is widely used in numerous areas. Among the various potential applications of ZnO that are applicable in today’s industries ranging from rubber to pharmaceutical, from textiles to agriculture, and from electronics and electrotechnology industries. The use of zinc oxide is not limited to only a certain region or area, but rather it is use
...nding on the type of raw materials used, the conditions of crystallization, zeolite crystallinity degree and the desired composition. After that, the crystallized zeolite is separated using rotary vacuum filters and washed with water. These zeolites then undergo few treatments to convert it into catalytic acitve material. The NaY zeolite is exchanged with ammonium ions to get rid of the sodium ions in an ionic exchange tanks which is then filtered out and sprayed with the exchange solution. The excess salts on the exchanged zeolites are removed by washing it. During hydrothermal treatment of the zeolite, it is partially dealmuninated and stabilized and the sodium ions that remains is moved to exchangeable position. The degree of dealumination and unit size of the product is determine through calcination conditions to obtain the microcrystallize product of zeolite.
Zinc is known to prevent and treat the intoxication of lead which often proves more effective along with the combination of methionine or thiamine (Flora et al., 1989; 1991). Supplementation of zinc simultaneously with methionine or thiamine helps effectively reduce urinary excretion of ALA and the lead induced ALAD activity in the blood. It is suggested from such studies that the combination therapy including the essential nutrient elements and vitamins concurrently with exposure to lead could be more effective than treating the lead toxicity after exposure. This helps to reduce the absorption of lead in the gastrointestinal tract. Thus it can be attributed that zinc help to reduce the lead absorption
Physical and Chemical Properties (2001, January 16). In Material Safety Data Sheet. Retrieved March 19, 2014, from http://avogadro.chem.iastate.edu/msds/nh4no3.htm
Obtaining Zinc Oxide from Calamine Introduction Calamine is a mineral containing zinc carbonate (ZnCO₃) On heating it decomposes as: [IMAGE]ZnCO₃ ZnO + CO₂ (C = 12, 0 = 16, Zn = 65) This equation allows you to calculate a theoretical conversion of calamine into zinc oxide. As when using the theoretical conversion; [IMAGE]ZnCO₃ ZnO + CO₂ [IMAGE]65+12+48 65+16 + 12+32 [IMAGE]125 81 + 44 This means that one mole of calamine weighs 125g and when heated it produces 81g of zinc oxide and 44g of carbon dioxide. Therefore to work out how much zinc oxide is produced from 1g of calamine we divide 81 by 125.
Another widely used primary cell is the zinc-mercuric-oxide cell, more commonly called a mercury battery. It can be made in the shape of a small flat disk and is used in this form in hearing aids, and electric wristwatches. The negative electrode consists of zinc, the positive electrode is of mercuric oxide, and the electrolyte is a solution of potassium hydroxide. The mercury battery produces about 1.34 volts.
The concept of displacement reaction of Zinc in cooper sulphate is exothermic, as heat is released out while reacting. A powder substance Zinc reacts faster, when it is added to cooper sulphate solution as the total surface is high. After reaching of the peak, the temperature started falling down, as the solution starts cooling down and Heat is lost in the surrounding. An ideal situation shows the change in temperature, which we can use it in calculations; It is possible that the concentration of copper sulphate was lower and therefore less zinc reacted, releasing less energy than expected. We took four different samples of zinc in order to check the difference in enthalpy. Zinc replaces cooper in cooper sulphate, because it is more reactive and it also has very low solubility. So, this is how with the help of redox reaction we determined the enthalpy change
Zinc is a fair conductor of electricity and burns in air with a bright bluish-green flame producing white clouds of the oxide.
This article focuses on the chemical structure of FePO4 between 294K and 1073K of thermodynamic scale, through high accuracy x-ray diffraction experiments. From the relatively lower temperature range, it acquires the chemical arrangement of an α-Quartz trigonal as shown below. However, as temperature steadily rises, there exists a series of minor changes, such as β-Tridymite hexagonal change at 870 °C. Hydrated amorphous FePO4 was synthesized in which a solution of (NH4)2HPO4 and FeSO4·7H2O was irradiated by an ultrasonic wave. Materials prepared are: (1) an amorphous sample prepared by heating
The process of refining zinc has two main steps: roasting and electrolysis. Both of these processes use a lot of energy. The roasting stage involves heating the furnace chamber up to temperatures between 700 oC and 1000oC Roasting is a way of oxidizing zinc sulphide and getting impure zinc oxide also known as "Z...
Graphite oxide will be synthesized by graphite powder through pre-oxidation and oxidation process based on Hummers and Hummers Improved method (Marcano et al., 2010). 20 g of graphite powder will be stirred in a heated solution of 30 ml H2SO4, 10 g K2S2O8 and 10 g P2O5 at 80°C for 30 minutes until dark blue mixture will be formed. The mixture will be cooled to 25°C for 6 hours. After that deionized water will be added and the ingredient will be filtered and washed until filtrate become neutral pH. Then, the filtrate will be dried overnight in vacuum desiccator at 25°C. 460 ml of concentrated H2SO4 will be used to oxidise the graphite in the ice bath after the drying process. KMnO4 will be added slowly with stirring and temperature of suspension will be maintained at 20°C.Then, the ice bath will be removed and the suspension will be heating up in an oil bath at 35°C for 2 hours until the suspension is thickening and effervescence paste in brownish grey colour will b...
To investigate the temperature change in a displacement reaction between Copper Sulphate Solution and Zinc Powder
There are two basic types of pyrotechnic materials: single component and two component systems. Single component materials will either burn if ignited, or explode if ignited when enclosed, since the oxidizer and fuel are in the same mixture. Flash paper, for example, is a partially nitrated cellulose and contains both fuel and oxidizer internally. The traditional black powder has potassium nitrate as the oxidizer, and sulfur and charcoal as fuels.
Advanced ceramics is composed of inorganic, non-metallic materials made from synthetic raw materials as oxides, carbides, and nitrides especially of the elements aluminum, boron, barium, magnesium, silicon, titanium, and zirconium[1]. Corundum (α-alumina) is considered as an important advanced ceramic materials due to its wide range of applications including high strength materials, electroceramics, catalysts, catalytic supports and adsorbent [2][3]. The advantages of alumina are hard, high resistant to acid and bases, allowing very high-temperature resistance applications and possessing very high wear resistance[4][5]. Alumina is a structurally complex oxide being several different metastable phases (γ, δ & θ-alumina) possible,
Zinc is an essential trace element for many living organisms. While this can be said about other essential metals, zinc is unique in its physiochemical properties that give it the ability to interact with donor groups of different ligands, resulting in a broad range of stability constants and diversity of the biological functions and processes that zinc is involved in. It was discovered and recognized as a new metal in the eightieth century, While its biological essentiality was found by Raulin for the growth of Aspergillus niger In 1869 [1]. In 1933 Zinc was found essential for the growth of animals while studying its effect on rats. [2]