Residential broadband market overview Essay Example for Free

Residential broadband market overview EssayLimestone is a shudder of which was one time the bones and shells of ocean animals. These died and collected as sediments at the fag end of seas, oceans and lakes. Chemical name Calcium degree centigradeate Chemical gradeula CaCo3 Alternative names Chalk, marble Limestone erect be utilise to prep ar a number of new materials. For this to happen limestone must on a lower floorgo endothermic decomposition. thermic decomposition is used on a large scale in fabrication to manufacture chemical substances. When limestone bear up underes thermal decomposition it produces atomic number 20 oxide (CaO) Quicklime is produced in refractory-lined kilns. In most kilns, limestone is fed in at the top of the shaft and calcium oxide is drawn from the bottom. Air is blown in at the base and burns with fuels part of the way up the kiln. The products of combustion of the fuel is mostly carbon dioxide gun for hire which escapes through vents a t the top of the shaft. Various fuels argon used e. g. c anele, rock oil, natural gas and coke depending on the local fuel costs. The temperature created by these fuels reaches over chiliad? C in the middle of the kiln. around modern kilns produce up to 300 tonnes/day of quicklime. Most quicklime is sold as a granular product but there is a growing market for the finely crushed solid.Limestone is one of the worlds most common minerals. Because it is cheap and readily available it grades an of the essence(predicate) part of many an(prenominal) other minerals. Once limestone has been converted to quicklime, the quicklime is used to form slaked lime. quelled lime (calcium hydroxide) is do by adding a little urine to quicklime. Powdered limestone Put in lakes to squander sulphurouss in the water Put on soil to neutralize acid soil. tout ensemble disceptations be made up of different minerals. In other words, minerals argon the chemical constituents of rocks although you ca nt tardily tell what their chemical composition is from their names.Sedimentary rocks are made of sediment formed when all other types of rock crack down (erosion) or break down because of the effects of weather (weathering). The particles of rock are transported by water or wind or ice to a low point on the solid ground (a sea or a valley). Gradually, over cardinals of years, they are converted to rock. The particles of rock form layers of sediment. Gradually to a keener extent and more layers form on top of each other over thou rachiss of years. The weight of the layers on top causes the bottom layers to be pressed together or compressed so the particles fuse together.This is shout outed CEMENTATION. Over millions of years the layers of rock build up into what are called strata. Particles can be rubbed of sedimentary rock because it is the softest type of rock. Different coat particles form different kinds of rock. Very fine particles wish well mud form mudstone. Larger gr ains deal sand form sandstone. Gravel and pebbles form conglome evaluates. Sedimentary rocks like Shale can be formed under the sea also. The shells from millions of tiny marine animals can build up on the sea floor. These shells are made from calcium carbonate.When these shells become slowly compressed together they form the rock limestone. When acid is added to this rock, it fizzes. As sediments collects, the bodies of plants or animals patch up into them. The bodies become buried and gradually turn to rock as there is no oxygen gas to allow them to rot. Over millions of years these bodies turn into fossils. Fossils are only found in sedimentary rocks. When runniness rock is beneath the come forward of the earth it is called magma, but when it comes out of the ground it is called lava. When they cool, they become solid and form the rocks we call igneous rocks.Magma and lava are made up of compounds called silicates. They are made from the elements silicon and oxygen, as adva ntageously as other elements like aluminium and magnesium. As the liquid rock cools it forms crystals. The size of the crystals depends on how apace it cools. Granite is formed when magma cools slowly under the ground so it has large interlocking crystals. This is called an intrusive igneous rock. When lava is erupted from a volcano it cools rapidly in the air so it has small interlocking crystals. This is called an extrusive igneous rock. An deterrent example of this type of rock is basalt.The structure of existing rocks can be changed by contact with magma or great pressure from underground. When this happens, the rock is said to have metamorphosed. (This just means changed. ) Any kind of rock can metamorphose. Clay and Shale (which are sedimentary rocks) can be changed by pressure until they become specify. This allows the slate to be split into layers easily. This is one reason why slate can be used for roofing material. If slate is then heated even more and put under more pr essure it forms a rock with bands of interlocking crystals. This rock is called Schist.Limestone is turned into marble when the amply temperatures underground break up the shells and they then amend as smooth, hard crystals. Scientists think ha the earth has been in existence for about 4500 million years. In the beginning, the surface was liquid, but gradually it cooled liberal for a solid crust to form. (About 3700 million years ago).The earth has had an atmosphere of gasses since it was formed but the types and amounts of each gas has changed. The earths crust is much thicker under the continents than under the oceans. Continental crust is about 40km thick compared to 10km for the crust under the oceans.Below the crust is a semi-liquid area called the mantle. The magnetic core of the earth is called the core and it is made of the metals Iron and Nickel. Because different parts of the earths crust are moving slowly in different directions, huge stresses and strains are set up. These can cause the rocks to become tilted, folded (bent) or faulted (split). They may even be turned upside down. Sedimentary rocks are softer than other types of rocks and fold more easily when compressed (squashed). If this happens on a large scale, then Fold mountains like the Alps or Himalayas are formed.A downward dip or fold is called a Syncline and an arch is called an Anticline. Brittle rocks fracture (fault) under stress. The earths crust is not a continuous layer but is made up of many let on units called Tectonic Plates. The plates move by convection currents in the molten rock of the Mantle. This moves the plates very slowly at the rate of a few centimetres a year. Over millions of years the continents have separated to reach their present positions. When an naval plate moves below a continental plate, the rock gets very hot and melts to form Magma. This then reaches the surface in Volcanoes.Also, where the oceanic plate moves downwards, a very deep area of sea floor is formed. These types of areas are called Ocean Trenches. Formation of scorch and oil In the carboniferous Era, which lasted 65 million years and finish 280 million years ago The British Isles was on the equator. The land was tropical forest. Coal was made from defunct animals and plants. The plants did not rot because they got covered in mud so no oxygen could get to them. The coal seams were formed by weight of new deposits squashed the tree layers into thin seams. Coal was formed 280 million years ago. Fractional DistillationWhen oil is pumped from the ground it is as a thick, black, foul olfactory sensation substance called rude(a) Oil. It is a mixture of chemicals called hydrocarbons. A mixture is just a mix of chemicals. The many hydrocarbons in crude oil may be separated into individual chemicals called Fractions by a lick called Fractional Distillation. Crude oil is a mixture of Hydrocarbons. They can be separated by putt the oil into a fractioning column. The crude oil is heated on its way into the column so that the oil is evaporated. This turns the liquid into a gas. The vapour then moves into the column.The chemicals with the least/most?molecules (more carbon atoms) move to the top e. g. gasolene. As the molecules become heavier, their stewing points increase. Once at the correct temperature the vapour condenses to a liquid and is run off. Crude oil contains most fuel and bitumen yet we do not need it all. We need lots of flatulency (which contains 5-10 carbon atoms) but we have too much fuel oil etcetera (over 70 carbon atoms), so what we do is this. We break up large useless molecules to stimulate small, useful molecules like petrol by a process called cracking. Paraffin is a general name for a group of gigantic hydrocarbons used as fuels.If mixed with pieces of porous porcelain as a catalyst, it can be made to undergo thermal decomposition or cracking. Porous means lots of holes, which gives a large surface area. Thermal decomposit ion means breaking something down with heat. Fractional distillation of petroleum (crude oil) produces different products because petroleum is a mixture of hydrocarbons. The compound in each fraction have similar boiling points. The fractions with higher boiling points tend to contain molecules with more carbon atoms. These bigger molecules are long chained and have large molecular masses.When these are burnt they produce sooty flames. They are very viscous (syrup-like). As a result there is high demand for smaller molecules and less demand for these massive molecules. The oil industry tries to balance the problems of supply and demand by converting the less saleable fractions into saleable fractions. The main way in which this is done is by the process known as cracking. The counterbalanceions are usually carried out at high temperature using a catalyst. We have seen that when large hydrocarbon molecules are broken open, or cracked, they produce smaller molecules like Ethene.It i s possible to join lots of Ethene molecules together to form a type of plastic. Simple make blocks like the paper clip (or Ethene) are called MONOMERS. When they are made into a long line of units we call it a POLYMER. The process which converts lots of Monomers to a Polymer is called PLYMERISATION. Common polymers include plastics, fibres and rubber. The elements present in Ethene monomers are hydrogen and carbon. What happens to convert monomers to polymers? Double bond breaks open during polymerisation. The name of the polymer made from Ethene is polyethene. Polyethene is more usually known as polythene.Another type of plastic is called Polyvinyl Chloride PVC for short, is strong, hard and less flexible than polythene. It is used to make pipes, guttering and electrical insulation. Combustion is another word for burning. Burning is a chemical reaction in which materials react with heat. The equation for burning is Fuel + oxygen = CO2 + water + energy. If there is not enough oxy gen in the air, the fuel dies not burn fully and the poisonous gas Carbon Monoxide is formed. several(prenominal) people are killed each year due to poisoning by carbon monoxide from badly refresh gas fires. Some fuels also contain Sulphur e.g.Coal. When this burns, it produces the gas sec dioxide. Sulphur + oxygen = sulphur dioxide. When this gas dissolves in rain, it produces acid rain. Waste gases from the exhausts of motor vehicles are also released into the atmosphere. They are also prudent for making the rain acidic and they pollute the air. Oxygen gas is Colourless and odourless Molecules are diatomic Approx. same density as air. Essential for combustion and respiration Reacts with most metals and non-metals to form oxides. Test for importunate oxygen = glowing splint re-lighting. Oxygen is a by-product of photosynthesis.Oxides can be acidic, basic (alkaline) or neutral. The link between the terms alkali and base is that an alkali is a base which dissolves in water. Non-m etals form acidic oxides. Metals form alkaline oxides. Many metals and non-metals are found as oxides in the earths crust. They are called ores. When elements react with oxygen it is called oxidation. During respiration and combustion, oxygen is used up and carbon dioxide is released back in to he air. All of the air is not used up because plants use up the carbon dioxide and release oxygen when they make their food by photosynthesis or respiration?This process has been happening for thousand of years. However, in the last two hundred years, the amount of carbon dioxide in the atmosphere has increased because There are many people on earth. We have burned millions of tonnes of fuel We have cut down thousands of square miles of forest. The carbon dioxide is acting like a blanket around the earth and it is trapping the heat from the sun, which leads to a raising of the earths temperature. This is called the greenhouse effect. acidic rain is made when acid gases dissolve in rain. Car bon dioxide is made when carbon burns in the oxygen in the air.When coal is burned it releases the gas sulphur dioxide. This also makes acid rain because it dissolves in rain to form sulphuric acid. Inside car engines, the temperature is hot enough to make nitrogen and oxygen join together to make nitrogen oxides. These dissolve in rain to make nitric acid. When acid rain falls on the earth it has the following effects Stonework on building is dissolved and crumbles onward The water in rivers and lakes becomes too acidic so plants and animals die You could reduce the acid level in rivers and lakes by putting limestone in it.The gases in the atmosphere originally came from volcanoes. The gases produced were carbon dioxide, hydrogen chloride, argon etc. There is not hydrogen left in the atmosphere because it was so light it evaporated and escaped. Distillation of oil 1. Vaporisation the thick oil is heated to from vapour/gas 2. Separation lighter molecules move upwardly and heavy molecules sink. Lighter molecules move upwards to the coolest region at the top. There is a temperature and density gradient. 3. muscle contraction the vapour is cooled to form a liquid (or solid).