AQA GSCE CHEMISTRY C1

CHEM

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  • Created by: zuggy
  • Created on: 05-01-13 17:50

Fundamental Ideas

  • ELEMENT- made up of one type of atom.
  • COMPOUND- 2 or more atoms chemically joined together.
  • ATOM-smallest particle
  • ELECTRONS- NEG -1
  • PROTONS- POS +1
  • NEUTRONS- NEUTRAL 0
  • IONIC BONDS-when a METAL reacts with a NON-METAL, ions are formed. Metals LOSE 1 or more electrons and become POSTIVELY  charged ions. Non-metalS GAIN 1 or more electrons and become NEGATIVELY charged.
  • COVALENT BONDS - when NON-METAL reactthey SHARE electrons
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LIMESTONE

  • LIMESTONE CYCLE
       1 -CaCO3-->CaO+CO2  Calcium carbonate thermally decomposes into calcium oxide and carbon dioxide                                        THERMAL DECOMPOSITION
       2-CaO+H2O-->Ca(OH)2   Calcium oxide(QUICKLIME) + some water --> calcium hydroxide.
       3 -Ca(OH)2+H2O-->Ca(OH)2(ag)   Calcium hydroxide(SLAKED LIME) + more water --> calcium hydroxide solution(LIMEWATER)
       4 -Ca(OH)2(ag)+CO2-->CaCO3   Calcium hydroxide solution + carbon dioxide --> calcium carbonate.
  • Limewater- used as a test for carbon dioxide-turns cloudy if it is CO2 positive.
  • Calcium hydroxide-an alkali. Can react with acids in a nutralisation reaction to form a calcium salt and water. Used by farmers to improve acidic soil, raising the pH.
  • CEMENT=LIMESTONE+CLAY
  • CONCRETE= aggregate + water + cement + sand.
  • MORTAR=CEMENT+SAND +WATER
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QUARYYING

Quarrying

Pros: 1. Job opportunities.2. Used as a landfill site afterwards.3. Can be later filled with water, turned into a reservoir and used for leisure activities.

Cons: 1. Noise pollution.2. Harms wildlife. 3. Eyesore.4. Dust affecting crops, etc.

CARBONATES

acid + carbonate---------------------------> carbon dioxide+salt+water

Carbonates react with dilute acid to form a salt, water and carbon dioxide.

·         Limewater turns cloudy in the test for carbon dioxide gas. A precipitate of insoluble calcium carbonate causes the cloudiness.

·         Metal carbonates decompose on heating to form the metals oxide and carbon dioxide.

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METAL

  • To get pure metal from a METAL OXIDE.we must add carbon.The carbon removes the oxygen to form carbon dioxide.This is a REDUCTION reaction,only used when CARBON is more reactive.
  • We extract iron from its ore in a blast furnace
  • OXIDATION IS LOSS of electrons
  • REDUCTION is GAIN of electrons
  • When METAL is more reactive than a carbon ,ELECTROLYSIS IS USED.
  • METAL always forms at NEG electrode

Extracting from COPPER RICH ORES

SMELTING-heating ore in a high furnace to produce crude copper

Also electroylsis is used to purfiy impure copper from SMELTING

  • Aluminium- silvery & shiny, with a low density, and is also a very good conductor. It is easy to shape and draw into wires. It does not corrode easily- surface atoms react with O2 giving an aluminium oxide layer which stops corrosion. Extracted using electrolysis.
  • Titanium- silvery white metal, very strong and corrosion-resistant due to an oxide layer. It has a very high melting point, used in replacement hip joints.  Expensive to extract and take a long time.
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metals 2

  • Copper - smelting: copper ore is heated very strongly to make crude copper, purified by electrolysis.
  • Copper - Electrolysis- adding sulphuric acid to produce copper sulphate solution, before extracting the copper. However, copper-rich ores are running out, scientists need to learn to extract from low-grade ores.
  • Phytomining - plants are used to absorb copper compounds from the ground. Then they are burnt and copper is extracted from the ashes. Could be planted on **** heaps-waste from extraction of copper rich ores.
  • Bioleaching - Bacteria feed on low-grade ores by different processes, and we get a solution of copper ions- 'leachate' from waste copper ore.
  • Metals in the middle block of the periodic table-transition metals, mostly good conductors and strong.
  • Metals in construction:
        ~Pros: -they are strong. -bent into shape -can be made into flexible wires. -good electrical conductors.
        ~Cons: -obtaining metals from ores causes pollution and uses resources. -metals are more expensive. -iron and steel can rust.
  • DISPLACEMENT REACTION-a metal more reactivr can displace from a solution
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CRUDE OIL

  • Crude oil- a mixture of different length chains of hydrocarbons.
  • Crude oil- seperated by fractional distillation-different temperatures in the column are according to the boiling points of hydrocarbons.
  • Methane: CH4  Ethane: C2H6  Propane: C3H8  Butane: C4H10  Pentane: C5H12.
  • CnH2n+2. =alkanes
  • Alkanes- saturated fats. Alkenes: formula of CnH2n, unsaturated fats with a doubles bond in.
  • Burning fuels are a process of combustion and incomplete combustion, both producing water. Incomplete combustion produces carbon monoxide when there isn't enough oxygen present. Complete- carbon dioxide produced.
  • Incomplete combustion- soot, containing carbon and unburnt hydrocarbons-particulates-causes global dimming.
  • Sulphur dioxide is also produced, which causes acid rain. So can nitrogen oxides.
  • Producing carbon dioxide contributes to global warming.
  • Biofuels-made from animal/plant products and are renewable. Biodiesel can be made from vegetable oils extracted from plants. It is carbon neutral. However, growing plants uses up space for growing food.
  • Ethanol-can be made from sugar cane, and can be misxed with petrols. It saves using up dwindling crude oil supplies.
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HYDROCARBONS

  •  Large hydrocarbon molecules can be broken down into smaller molecules by cracking. This produces one alkene and at least one alkane. It can be done by: 1. heating hydrocarbon vapours and steam to a very high temperature. 2. passing hydrocarbon vapours over a hot catalyst. This is thermal decomposition.
  • Alkenes react with bromine water turning it from orange to colourless.
  • Alkenes are also known as monomers. They can be joined with many other monomers to make a polymer-polymerisation.
  • Polymers are plastics, used as bags, bottles and containers.
  • Smart polymers can be made with special properties. Hydrogels are polymers that can absorb a lot of water-like in nappies and dressings for wounds.
  • Many polymers are not biodegradeable-the plastic doesn't break down when left in the environment.
  • New biodegradeable plastics are being produced from plants such as cornstarch.
  • Ethanol: C2H6O, but often written as C2H5OH to show it is an alcohol. It can be made my fermentation of sugar using yeast. Enzymes in the yeast cause sugar to convert to ethanol and CO2. It is renewable and done at room temperature. However, only a dilute aqueous solution is made-it has to be distilled further.
  • It can also be made from the hydration of ethene (which has been made by cracking), by reacting ethene at a high temperature with a catalyst. The reaction can be run continuously, but uses a lot of energy.
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plant oils

  • Some seeds, nuts and fruits are rich in vegetable oils, extracted by pressing the plant material, and then removing the water and impurities.
  • Some are extracted by distilling the plant material mixed with water, creating a mix of oil and water which can be seperated.
  • Vegetable oils provide a lot of energy and good nutrients. They can also be used as fuels, and are used to make biofuels. They have hydrocarbon chains, and have double bonds so they are unsaturated. If there is more than one double bond in each molecule, they are called polyunsaturated fats.
  • Boiling points of vegetable oil are higher than water, so food is cooked at higher temperatures, and cooks faster. Also, the colour and texture is change and it tastes nicer. Some oil is absorbed, increasing energy content of the food.
  • Hydrogenation-hardening- unsaturated oils can be reacted with hydrogen to make saturated fats-alkanes. Conditions of 60 degrees celsius and a nickel catalyst is needed, and this makes the oils solid at room temperature.
  • Oil and water are imiscible, and seperate gradually when mixed together, forming an emulsion. Emulsifiers can stable the emulsion, because they have a hydrophobic tail which is atttached to the oil droplet and a hydrophyllic head which is attached to the water. This improves texture, appearance and sticks to solids. However, they are high in fat, and saturated fats have been known to be linked to heart disease.
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EARTH

 

  • Structure of the Earth- almost spherical with a diameter if 12800km. It has a thin, solid crust varying in thickness rom 5km to 70km. The mantle under the crust is about 3000km thick, and is almost all solid but parts of it flow very slowly. The core is about half the diameter of Earth, with a lot of nickel and iron which are magnetic. It has a liquid outer part and a solid inner core. The atomosphere surrounds the planet, within 100km of the surface.
  • Convectional currents: the crust is split up into pieces-tectonic plates which move due to convectional currents in the mantle due to radioactive processes in the core. It can cause volcanoes, earthquakes and create mountains.
  • Alfred Wegener- he believed that the plates moved and that the continents fit together like a jigsaw piece. other scientists thought that the Earth was shrinking as it cooled.
  • The earth was created about 4.5 billion years ago. At first the surface was covered with volcanoes releasing CO2, water vapour and nitrogen. As it cooled most of the vapour condensed to form oceans. Some scientists believe there was also methane and ammonia present at the time. In the next two billion years algae and plants evolved, using CO2 and releasing O2, increasing the amount of oxygen.
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miller

  • In 1952 Miller and Urey, 2 scientists did an experiment based on what was believed to be in the early atmosphere. A mixture of water, ammonia, methane and hydrogen used and a high voltage spark to simulate lightening. After a week amino acids (one of the building blocks for proteins) had been made.
  • This mixture of gases in the atmosphere is known as the primordial soup.
  • Today, the air is: -78% Nitrogen -21% Oxygen -0.9% Argon -0.04% CO2 and trace amounts of other gases.
  • Seperating gases: 1. Liquefy the air at -200 degrees celsius 2. Feed it into a fractional distillation column. 3. Gaseous nitrogen is seperated, and further distillation is used to make pure oxygen and carbon. It is used in industry as raw materials.
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tectonic

DIVERGENT BOUNDARY

plates moving away from each other and new plate material from the mantle is added to the lithosphere.

CREATES NEW LAND

CONSERVATIVE BOUNDARY

Lithosphere is NEITHER CREATED NOR DESTROYED

move laterally realtive to each other

CONVERGENT BOUNDARY---DESTROYS LAND

plates are approaching each other

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