Section 6: Silicone And Nitrogen

SECTION : SILICONE AND NITROGEN Silicone Silicon is the second most abundant element found on earth, namely around 28%. Even though it is abundant, silicon is not found in its natural form, but is found in silicate minerals and as silica (SiO2 ). Quartz is a form of pure SiO2 crystal, while sand, agate, onyx, opal, amethyst and flint are SiO2 with trace amounts of impurities.Silicon can be obtained by mixing silica and coke (as a reducing agent) and heating it in an electric furnace at a temperature of around 3,000 °C. Reaction: SiO2 (l) + C(s) Si(l) + 2 CO(g) Silicon is generally used to make transistors, computer chips, and solar cells. Meanwhile, various silicon compounds are used in many industries. Silica and silicates are used to make glass, ceramics, porcelain, and cement. Silicon reacts with carbon to form carbide (SiC) Nitrogen and Nitrogen Compounds Nitrogen is the most abundant element that can be easily accessed by humans. In nature, nitrogen forms as the compound N2 with levels of 78.03% by volume and 75.45% by weight. Nitrogen is a colorless, odorless and tasteless gas, and melts at –195.8 °C and freezes at –210 °C. Nitrogen is obtained by multilevel distillation of liquid air. First the air is filtered to clean it of dust. The clean air obtained is then compressed which causes the air temperature to increase. After that, it is cooled. At this stage, water and carbon dioxide freeze so they can be separated. After passing through the cooling tower, the air is then expanded so that the temperature will drop again and some of the air will melt, while the air that has not yet melted is circulated/flown again into the compressor. The uses of nitrogen include the following.       Most of the nitrogen is used to make ammonia (NH3). Used to make nitrogen fertilizer, such as urea (CO(NH2)2) and ZA(NH4)2SO4). As an inert gas shell to remove oxygen in the manufacture of electronic devices because of its inert nature. Used as a coolant to create low temperatures, for example in the food processing industry. Create an inert space for storing explosive substances. Fill empty space in the thermometer to reduce evaporationmercury. Some nitrogen compounds are as follows. 1. Ammonia The form of ammonia is a gas with a distinctive and very pungent odor,colorless, with a boiling point of –33.35 °C and a freezing point of –77.7 °C.Ammonia is made using the Haber-Bosch process, at a temperature of 370 – 540 °C and a pressure of 10 – 1,000 atm, using a Fe3O4 catalyst . The catalyst functions to expand the lattice and enlarge the active surface, while high temperatures are used to obtain the desired reaction rate. Reaction: N2 (g) + 3H2 (g)2NH3 (g) On a laboratory scale, ammonia is made by reacting ammonium salts with a strong base while heating. Reaction: NH4Cl + NaOH NaCl + H2O + NH3 Uses of ammonia include:   Make fertilizer, such as urea (CO(NH2)2) and ZA (NH4)2SO4 ). Makes other nitrogen compounds, such as nitric acid, ammonium chloride, and ammonium nitrate.  As a coolant in ice factories because liquid ammonia evaporates easily and absorbs a lot of heat.  Makes hydrazine (N2H4), rocket fuel.  Used in the paper, rubber and pharmaceutical industries.  As a refrigerant in compression and absorption systems. 2. Nitric Acid Nitric acid is a strong acid, which can dissolve almost all metals, except gold and platinum. Nitric acid is a clear liquid at ordinary temperatures and can mix perfectly with water in all proportions.Nitric acid is made through three stages, known as the Oswald process, as follows. First, excess ammonia and air are flowed through the Pt – Rh catalyst at a temperature of 950 °C, then cooled until the temperature reaches 150 °C where the gas is mixed with air which will produce NO2. NO2 (g) and residual air are channeled to the base of the tower, then sprayed with water at a temperature of around 80 °C, a solution containing 70% HNO3 will be obtained . Reaction: 4NH3 (g) + 5O2 (g) 4NO(g) + 6H2O(g) 2NO(g) + O2 (g) 2NO2 (g) 4NO2(g) + O2(g) + 2H2O(l) 4HNO3 (aq) Nitric acid is widely used for fertilizer (ammonium nitrate), medicine, and explosives, such as TNT, nitroglycerin, and nitro-cellulose. Nitric acid is also used in rocket propulsion systems with liquid fuel.