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Environmental Chem..

QuestionAnswer
Distillation is commonly used to separate [] from []. Ethanol from water.
Distillation process to separate ethanol from water: Step 1 - water and ethanol are heated, Step 2 - the [] evaporates first, [], then [] the ethanol evaporates first, cools, then condenses, Step 3 - the [] left [], [[, then []. the water left evaporates, cools, then condenses. The mixture is heated in a flask. Ethanol evaporates first as it's boiling point is lower. The ethanol vapour is then cooled and condensed inside the condenser to form a [] [] pure liquid. When all the ethanol has evaporated from the solution, the [] rises and the [] evaporates. the temperature rises and the water evaporates.
This is the sequence of events in distillation: [] → [] → [] → [] heating → evaporating → cooling → condensing.
"Several [] products are released when fuels burn. Several waste products are released when fuels burn. These do not just disappear and they can harm the environment by contributing to global w[], global d[] and [] []. by contributing to global warming, global dimming and acid rain.
Fuels burn when they react with [] in the []. when they react with oxygen in the air. If there is plenty of air, [] combustion happens. If there is plenty of air, complete combustion happens. Coal is mostly carbon. During complete combustion, carbon is [] to carbon dioxide carbon is oxidised to carbon dioxide: carbon + oxygen → carbon dioxide.
Carbon dioxide is a g[]h[] gas. Carbon dioxide is a greenhouse gas. Increasing [] of it in the atmosphere "contribute to global warming". Increasing concentrations of it in the atmosphere
Hydrocarbon fuels contain [] and []. Carbon and Hydrogen. During combustion, hydrogen is [] to water hydrogen is oxidised to water(remember that water, H2O, is an oxide of hydrogen). In general: hydrocarbon + oxygen → carbon dioxide + water.
Incomplete combustion: If there is insufficient air for complete combustion, [] combustion (also called [] combustion) happens. Incomplete combustion (also called (partial combustion) happens. Hydrogen is still oxidised to water, but instead of Carbon Dioxide, [] [] forms. Instead of Carbon Dioxide, Carbon Monoxide forms. Carbon monoxide is a t[] gas, so adequate [] is important when burning fuels. Carbon Monoxide is a toxic gas, so adequate ventilation is important when burning fuels. Solid [] (p[]) are also released Solid particles (particulates) are also released. These contain Carbon and are seen as [] or [] and are seen as smoke or soot. "Particulates cause global dimming. They reduce the amount of sunlight reaching the Earth’s surface."
Acidic oxides: Carbon dioxide dissolves in [] in the [] Carbon dioxide dissolves in water in the atmosphere to form a weakly [] solution to form a weakly acidic solution. This means that rainwater is naturally slightly acidic. However, some of the products from [] fuels make rainwater more [] than normal. Some of the products from burning fuel make rainwater more acidic than normal. This is [] rain. This is acid rain. Acid rain reacts with metals and rocks such as l[] such as limestone, causing damage to buildings and statues. Acid rain also makes rivers and lakes too [] for some aquatic life to survive. too acidic for some aquatic life to survive.
Acid rain damages the [] layer on the leaves of trees. Acid rain damages the waxy layer on the leaves of trees. This makes it more difficult for trees to absorb the [] they need for healthy growth and they may die. to absorb the minerals they need for healthy growth and they may die.
Sulfur dioxide: Coal and most hydrocarbon fuels naturally contain some s[] compounds some Sulphur compounds. When the fuel burns, the Sulfur it contains is [] to [] the Sulpur it contains is oxidised to Sulphur dioxide: sulfur + oxygen → sulfur dioxide This gas dissolves in water to form an [] solution to form an acidic solution. "It is a cause of" [] [] "acid rain."
Sulfur can be removed from fuels before they are used. ‘Low []’ petrol and diesel are widely available at filling stations to use in vehicles. 'Low Sulphur' petro and diesel. In power stations, Sulfur dioxide can be removed from the [] gases before they are released from chimneys. from the waste gases. The waste gases are treated with p[] l[]. powdered limestone. The Sulfur dioxide reacts with it to form calcium sulfate. This can be used to make plasterboard for lining interior walls, so turning a harmful product into a useful one.
Oxides of nitrogen: At the high temperatures found in an engine or furnace, nitrogen and [] from the air can react together. Nitrogen and Oxygen. They produce various [] of [] Oxides of Nitrogen, often called NOx (x ss). "These also cause acid rain."
Acid rain is a major pollution problem. It can be caused by the [] of fuels that contain []. It can be caused by the combustion of fuels that contain Sulphur. When this Sulphur is burned it produces the a[] gas [] []. It produces the acidic gas Sulphur Dioxide. Sulphur + Oxygen → Sulphur dioxide Car engines are also responsible for producing the acidic gases. The spark plug in petrol engines has enough energy to break apart stable nitrogen molecules and oxygen mo to form the acidic gas Nitrogen dioxide. Nitrogen + Oxygen → Nitrogen dioxide. Both Sulphur dioxide and Nitrogen dioxide will dissolve in r[] w[] rain water to produce [] [] acid rain.
The weathering of rocks by chemicals is called chemical weathering. Rainwater is naturally slightly acidic because [] [] from the air dissolves in it. Carbon Dioxide from the air dissolves in it. Minerals in rocks may react with the rainwater, causing the rock to be weathered. Some types of rock are easily weathered by chemicals. For example, limestone and chalk are made of a mineral called Calcium carbonate. When acidic rainwater falls on limestone or chalk, a [] [] happens chemical reaction happens. New s[] substances are formed in the reaction. New soluble substances are formed in the reaction. These are [] [] and the rock is []. These are washed away and the rock is weathered.
Some types of rock are not easily weathered by chemicals. For example, granite and gabbro are hard rocks that are weathered only slowly. Still some of their [] do react with the acids in rainwater some of their minerals do react with acids in rainwater to form new, [] substances weaker substances that crumble and fall away.
When fossil fuels such as coal, oil and natural gas are burned, [] [] and [] [] escape into the air. Carbon Dioxide and Sulphur dioxide escape into the air. Acid rain makes chemical weathering happen more quickly. Buildings and statues made from rock are damaged as a result. This is worse when the rock is limestone rather than granite. Acid rain also kills trees and fish.
Metal carbonates such as calcium carbonate break down when [] strongly. when heated strongly. This is called [] [] thermal decomposition. Here are the equations for the thermal decomposition of calcium carbonate: (oa means 'on arrow') Calcium carbonate → [heat oa] calcium oxide + carbon dioxide. CaCO3 → [heat oa] CaO + CO2. Other m[] c[] decompose in the same way. Here are the equations for the [] [] of copper carbonate: Other metal carbonates decompose in the same way. Here are the equations for the thermal decomposition of copper carbonate: copper carbonate → [heat oa] [], CuCO3 → [heat oa] [] copper carbonate → [heat oa] Copper oxide + Carbon dioxide, CuCO3 → [heat oa] CuO + CO2.
In the example of Calcium carbonate and Copper carbonate the products are a [] [] and [] [] the products are a metal oxide and a Carbon dioxide.
The carbon dioxide gas can be detected using l... limewater. Limewater turns cloudy [] when carbon dioxide is bubbled through it. turns cloudy white. Metals high up in the reactivity series - such as calcium - have carbonates that need a lot of [] to decompose them. that need a lot of energy to decompse them. Metals low down in the reactivity series - such as copper - have carbonates that are easily decomposed. This is why copper carbonate is often used at school to show these reactions. It is easily decomposed, and its colour change, from green copper carbonate to [] copper [], is easy to see to black copper oxide.
Limestone is a type of rock, mainly composed of calcium carbonate. Limestone is quarried (dug out of the ground) and used as a [] material. building material. It is also used in the manufacture of cement, mortar and concrete.
Carbonates react with acids to produce [], a [] and []. Carbon dioxide, a salt and water. For example: calcium carbonate + hydrochloric acid → carbon dioxide + calcium chloride + water; CaCO3 + 2HCl → CO2 + CaCl2 + H2O
Since limestone is mostly calcium carbonate, it is damaged by [] []. acid rain. Sodium carbonate, magnesium carbonate, zinc carbonate and copper carbonate also react with acids: when in contact with acids, they fizz and the carbon dioxide released can be detected using limewater.
When limestone is heated strongly, the calcium carbonate it contains decomposes to form calcium oxide. This reacts with water to form calcium hydroxide, which is an a[] alkali. Calcium hydroxide is used to [] excess acidity neutralise excess acidity, for example, in lakes and soils affected by acid rain.
Cement is made by heating powdered [] with []. powdered limestone with clay. Cement is an ingredient in mortar and concrete.
Limestone, cement and mortar slowly react with [] [] dissolved in rainwater Carbon dioxide dissolved in rainwater.
When an acid is dissolved in water we get a solution that's acidic, and alkalis make [] solutions. alkaline solution. If a solution is neither acidic nor alkaline we call it neutral. Pure water is neutral, and so is paraffin. Indicators are substances that, when they are added to acidic or alkaline solutions, change colour. Two indicators that are commonly used in the laboratory are Litmus and universal.
Litmus indicator solution turns red in acidic solutions and blue in alkaline solutions - and it turns purple in neutral solutions. Litmus paper is usually more reliable; it comes in red or blue, and has the same colour changes except when the solution is neutral the colour does not change.
Unlike litmus, universal indicator can show us exactly how strongly acidic or alkaline a solution is. Universal indicator has many different colour changes, from red for strong acids to dark purple for strong bases. In the middle, neutral pH 7 is indicated by green.
With universal indicator: neutral solutions are exactly PH 7, acidic solutions have pH values less than 7; alkaline solutions have pH values more than 7.
A chemical reaction happens if you mix together an [] and a []. acid and a base. The reaction is called neutralisation, and if you add just the right amount of acid and base together, what is made is a [] solution a neutral solution.
Metal oxides and metal hydroxides are two types of bases. For example copper oxide and sodium hydroxide. Here are general word equations for what happens in their neutralisation reactions with acids. metal oxide + acid → a salt + water; metal hydroxide + acid → a salt + water. Notice that a salt and water are always produced. The mixture usually warms up a little during the reaction, too. The exact salt made depends upon which [] and [] were used. which acid and base were used. Carbonates and hydrogen carbonates are two other types of base. They also make a salt and water when we [] them with []. When we neutralise them with acid. But this time we get carbon dioxide gas too. The reaction fizzes as bubbles of [] []are given off. This is easy to remember because we see the word 'carbonate' in the chemical names. bubbles of carbon dioxide are given off. These are the general word equations for what happens: acid + metal carbonate →[] acid + metal hydrogen carbonate → [] acid + metal carbonate → a salt + water + carbon dioxide; acid + metal hydrogen carbonate → a salt + water + carbon dioxide
When an acid is neutralised by a base, what is made is a salt. But the exact salt made depends upon which [] and [] were used which acid and base are used. The name of a salt has two parts: the first part comes from the [] in the [] used comes from the metal in the base used; the second part comes from the [] that was used the acid. If Hydrochloric acid is used, the second part of the salt's name is chloride; if Sulphuric acid is used, the second part of the salt's name is sulphate; if nitric acid is used, the second part of the salt's name is nitrate.
Carbon dioxide + water → Carbonic acid; Sulphur dioxide + water → Sulphuric acid; Nitrogen oxides + water → nitric acids. CO2+H2O → H2CO3; SO2 + H2O → H2SO4; NO2 +H2O → HNO3.
Distillation is a process that can be used to separate a [] [] from a [] of []. pure liquid from a mixture of liquids. It works when the liquids have different [] []. boiling points.
The alcohol in alcoholic drinks is ethanol.
Created by: Toluo