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36 Cards in this Set
- Front
- Back
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C1- Rocks and building materials |
Science C1 |
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Limestone and its uses |
Limestone is made mainly of calcium carbonate Limestone is used as a building material and to make calcium oxide and cement. Cement mixed with sand. aggregate and water makes concrete. Calcium carbonate decomposes when heated to make calcium oxide and carbon dioxide. |
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Reactions of carbonates |
Metal carbonates decompose when heated to produce the metal oxide and carbon dioxide. Carbonates react with acids to produce a salt, water and carbon dioxide. Carbon dioxide turns lime water cloudy. |
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The 'limestone reaction cycle' |
Thermal decomposition of calcium carbonate produces calcium oxide and carbon dioxide. Calcium oxide reacts with water to produce calcium hydroxide. Calcium hydroxide is an alkali that can be used to neutralize acids. Calcium hydroxide reacts with carbon dioxide to produce calcium carbonate. |
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Cement and concrete |
Cement is made by heating limestone with clay in a kiln. Mortar is made by mixing cement and sand with water. Concrete is made by mixing aggregate with cement, sand and water. |
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Limestone issues |
Limestone, cement and concrete are needed as building materials. Quarrying and processing limestone and its products have negative impacts on the environment. |
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Advantages and disadvantages of living by a limestone quarry. |
Advantages: More employment opportunities for local people. more customers and trade for local businesses. Improved roads. Disadvantages: Dust and noise. More traffic. Loss of habitats for wildlife |
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Extracting metals |
Metals are usually found in the Earth's crust. They are often combined chemically with other elements such as oxygen. An ore contains enough metal to make it worth extracting the metal. The method we use to extract a metal depends on it's reactivity. Unreactive metals are found in the earth as the metal. The oxides of metals less reactive than carbon can be reduced using carbon. |
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Iron and Steels |
Iron oxide is reduced in a blast furnace to make iron. Iron from blast furnace is too brittle for many uses. Most iron is converted into alloys called steels. Steels contain carefully controlled quantities of carbon and other elements. |
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Aluminum and titanium |
Aluminium and titanium resist corrosion. They also have low densities compared with other strong metals. Aluminum and titanium cannot be extracted from their oxides using carbon. Aluminum and titanium are expensive because extracting them involves many stages and requires large amounts of energy. |
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Metallic issues |
There are social, economic and environmental issues associated with exploiting the metal ores. Recycling saves energy and limited resources. There are drawbacks as well as benefits from the use of metals in structures. |
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Benefits of using metals |
They are strong. They can be bent into shape. They can be made into flexible wires. They are good electrical conductors. |
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Drawbacks of using metals |
Obtaining metals from ores causes pollution and uses up limited resources. Metals are more expensive than other materials such as concrete. Iron and steel can rust. |
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Fuels from Crude Oil |
Crude oil is a mixture of many different compounds. Distillation can be used to seperate mixtures of liquids. Most of the compounds in crude oil are hydro carbons, they contain only hydrogen and carbon. Alkanes are saturated hydro carbons. They contain as many hydrogen atoms as possible in their molecules. |
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Fractional distillation |
Crude oil is separated into fractions using fractional distillation. The properties of each fraction depend on the size of the hydro carbon molecules. Fractions with lower boiling points are less viscous and burn more easily. |
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Burning fuels |
Burning hydrocarbons in plenty of air produces carbon dioxide and water. Burning hydrocarbons in a limited supply of air may produce carbon monoxide and solid particles. Any sulfur compounds in the fuel burn to produce sulfur dioxide. Oxides of nitrogen can be formed when fuels burn under extreme conditions. |
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Cleaner fuels |
Many scientists believe that burning carbon dioxide from many fuels causes global warming. Sulpher dioxide and nitrogen oxides cause acid rain. Particulates cause global dimming. Pollutants can be removed from waste gases after the fuel is burnt. Sulfur can be removed from fuels before they are burned so less sulfur dioxide is given off. |
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Alternative fuels |
Biodiesel can be made from vegetable oils. Boifuels are renewable source of energy that could be used instead of fossil fuels. There are advantages and disadvantages of using biodiesel. Ethanol made from sugar is a biofuel. Hydrogen is a potential fuel for the future. |
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Advantages of Biodiesel |
It makes little contribution to carbon dioxide levels. Because the carbon dioxide was taken from the atmosphere by plants as they grew. |
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Disadvantages of Biodiesel |
The plants that are grown for biodiesel use large areas of farm land. |
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Cracking hydrocarbons |
Hydrocarbon molecules can be broken down by heating them with steam to a very high temperature or by passing their vapors over a hot catalyst. Cracking produces alkanes and alkenes. Alkenes are unsaturated hydrocarbons. Alkenes turn bromine water from orange to colorless. |
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Making polymers from alkenes |
Plastics are made of polymers. Polymers are large molecules made when many small molecules (monomers) join together. Alkenes can be used to make polymers such as poly(ethene) and poly(propene. |
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New and useful polymers |
New polymers are being developed all the time. Polymers are designed to have properties that make then specially suited for certain uses. we are now recycling more plastics and finding new uses for them. |
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Plastic waste |
Non-biodegradable plastics cause unsightly rubbish, can harm wildlife and take up space in landfill sites. Biodegradable plastics are decomposed by the action of microorganisms in soil. making plastics with starch granules in their structure helps the microorganisms break down a plastic. We can make biodegradable plastics from plant material such as cornstarch. |
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Ethanol |
Ethanol can be made by fermenting sugar using enzymes in yeast. Ethanol can also be made by hydration of ethene with steam in the presence of a catalyst. Using ethene to make ethanol needs non-renewable crude oil whereas fermentation uses renewable plant material. |
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Extracting vegetable oil |
Vegetable oils can be extracted from seeds, nuts and fruits by pressing or by distillation. Vegetable oils provide nutrients and a lot of energy. They are important foods and can be used to make bio fuels. Unsaturated oils contain carbon-carbon double bonds (C=C) and so they decolourise bromine water. |
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Cooking with vegetable oils |
Vegetable oils are useful in cooking because of their high boiling points. Cooking in oil increases the energy content of foods and changes the flavour, color and texture of the food. Vegetable oils can be hardened by reacting them with hydrogen at 60 DC with a nickel catalyst. This makes them solids at room temperature that are suitable for spreading. |
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Everyday emulsions |
Oils do not dissolve in water but oils and water can be used to produce emulsions. These have special properties. Emulsions made from vegetable oils are used in many foods. Emulsifiers stop oil and water from separating into layers. Emulsifiers have molecules in which one part is hydrophobic and one part is hydrophilic. |
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Food issues |
Vegetable oils are high in energy and provide nutrients. Vegetable oils are believed to be better for health than saturated fats. Emulsifiers improve the texture of foods enabling water and oil to mix. This makes fatty foods more palatable and tempting to eat. |
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Benefits of using vegetable oils and emulsifiers in foods. |
High in energy contain nutrients contain unsaturated fats better for health. |
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Structure of the Earth |
The Earth is made of layers called the core, mantle and crust with the atmosphere around the outside. The Earth's limited resources come from its crust, the oceans and the atmosphere. |
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The restless Earth |
The Earth's crust and upper mantle is cracked into tectonic plates which are constantly moving. The tectonic plates move because of convection currents in the mantle that are caused by radioactive decay. Earthquakes and volcanoes happen where tectonic plates meet, but it is difficult to predict accurately when and where earthquakes will happen. Wegener's theory of continental drift was not accepted for many years. |
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The earth's atmosphere in the past |
The Earth's early atmosphere was formed by volcanic activity. It probably consisted mainly of carbon dioxide. There may also have been water vapor together with traces of methane and ammonia. As plants spread over the Earth, the levels of oxygen in the atmosphere increased. |
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Life on Earth |
There are many theories about how the life began on Earth. One theory states that the compounds needed came from reactions involving hydrocarbons and ammonia with lighting providing energy. All the theories about how life started on Earth are unproven and so we cannot be sure how life began. |
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Gases in the atmosphere |
Most of the carbon dioxide in the early atmosphere became locked up in sedimentary rocks. About four-fifths (almost 80%) of the atmosphere is nitrogen, and about one-fifth (just over 20%) is oxygen. The main gases in the air can be separated by fractional distillation. These gases are used in industry as raw materials. |
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Carbon dioxide in the atmosphere |
Carbon moves into and out of the atmosphere due to plants, animals, the oceans and rocks. The amount of carbon dioxide in the Earth's atmosphere has risen in the recent past largely due to the amount of fossil fuels we now burn. |
