Chemistry 1

Chemistry 1

The Early Atmosphere
1. formed by gasses produced by volcanoes
  1. contained large amounts of: carbon dioxide & water vapour
    1. Hardly any oxygen and small amounts of other gasses
    2. oceans
2. the earth was very hot to start with.
  1. no oceans
    1. as the earth cooled the water vapour condenced to form liquid water
The Atmosphere now
Rocks and Their Formation
1. Igneous Rocks
  1. Are formed when magma or lava solidifies.
  2. made of interlocking crystals
  3. have small crystals if the liquid rock cooled quickly
  4. have large crystals when rock cools slowly
2. Sedimentary Rocks
  1. layers of sediment are compacted together over a long time being buried under more layers
  2. it errodes earier than igenous or metaphorphic
  3. made from rounded grains, may contain fossils
  4. include chalk and limestone- natural forms of callcuim carbonate
3. Metamorphic Rocks
  1. formed from existing rocks by heat or pressure
    1. buried or from nearby magma
    2. causing new interlocking crystals to grow
  2. Marble (metamorphic rock) is formed from chalk or limestone
4. Limestone and its uses
  1. Buildings
  2. base for roads or railwaus
  3. mostly made form calcuim carbonate (CaCo3)
    1. raw material used to make Glass, cement and concreate
      1. Limestone is heated when making cement and glass
        the heat decomposes the calcium carbonate in it to form calcium oxide (CaO) and carbon dioxide (CO2).
        in a process called THERMAL DECOMPOSITION Calcuim carbonate - calcium oxide + carbon dioxide
        Thermal Decomosition
        Metal Carbonates decompose when heated to form an oxide and carbon oxide.
        some decompose more easily than others
Reactions of calcium carbonates
1. The Limestone Circle
2. Lime water
  1. fully diddolved Calcium hydroxide in water
  2. used to test for CO2. Turns milky.
    1. CO2 + Ca(OH)2 = CaCo3 (s) + H2O. The solid is suspended in the water
3. calcium carbonate is also known as lime stone CaCo3
4. calcium carbonate, oxide and hydroxide can all be used to nutralise acidic compounds.
  1. some soils are acidic. Farmers use it on their fields to help the crops grow
Indigestion
1. our stomachs produce Hydrochloric acid
  1. Kill bacteria in our food
  2. help digestion
2. somethimes too much is produced. causing pain called indigestion
3. testing remideis
  1. neutral liquids have a pH of 7. Acids less than 7
  2. when an indigestion remedy is added to an acid. some of the acid is neutralise. pH increases
    Nota:
    - to make the investigation a fair test, you must use the same volume of acid each time at the same consentration, and use one dose of each remedy. the remedy that produces the highest pH t the end has neutralised the most acid.
Neutralisation
1. in indigestion
  1. the remedies contain anti acids that nutralise the excess acid.
    1. anti acids contain bases, they react with the acids and nutralise them
      1. some bases are soluble. a bases disoved in water is called an Alkali
  2. acid+ base - salt + water
2. three differnt types of compounds used to nutralise acids
  1. metal oxides (such as copper oxide, CuO )
    1. acid + metal oxide - salt + water
  2. metal hydroxides (such as sodium hydroxide, NaOH )
    1. Acid + metal hydroxide - salt + water
  3. metal carbonates (such as copper catbonate, CuCo3)
    1. acid + metal carbonate - salt + water + carbon dioxide
3. Naming Salts
  1. salt is made from a metal and non-metal compound
  2. hydrochloric acid produces chloride salts
  3. nitric acid produces nitrate salts
  4. slufuric acid produces sulfate salts
Chlorine
1. the dangers
  Nota:
  - chlorine is a toxic gas. this makes it useful as a disinfectant because it kills microorganisms. this also makes chlorine hazardous. chlorine is very useful in industry, and millions of tonnes of it are produced every year.
  1. ohlorine gas is toxic
2. using
  Nota:
  - Sea water contains a lot of dissolved sodium chloride. chlorine gas can be obtained from sea water by electrolysis. chlorine is used to make bleach, and to make plastics such as polychloroethene (PVC)
  1. PVC
  2. Bleach
Electrolysis
1. of water
  1. produces hydrogen and oxygen gasses
2. only works on a D.C
Testing for Gasses
1. hydrogen:
  1. hold a glowing alighted splint int the mouth of the test tube if the gas is hydrogen, it will explode with a squeaky pop
2. oxygen
  1. hold a glowing splint into the mouth of the test tube. if the gas is oxygen it will relight.
3. chlorine
  1. hold a peice of damp blue litmus paper in the test tube. if the gas is chlorine it will bleach the paper white
Ores
1. some metals are found as elements in the earths crust. the metal is not combined with other elements. these metals are very unreactive.
2. extracting metals
  1. most metals are found as part of a compound in rocks. if the rock has enough metal compound to extract the rock is called an ore
3. metals such as iron are exctracted their compounds by heating them with carbon. More reactive metals such as aluminium are extracted by melting the ore then carrying out electrolysis
Oxidation and reduction.
1. most metal oxides react with oxygen this causes corrosion. eg i ron + oxygen = iron oxide. the iron has been oxidised because it has gained oxygen.
2. many metal ores contain oxides. the metal is extracted by removing the oxygen. aluminium oxide - aluminium + oxygen. The aluminium oxide has been reduced, the oxygen has been removed
recycling metals
1. when a metal object has reached the end of its life the metal can be melted down and made into something new. recycling has many beifits.
2. recycling menas the earths supply of metals will last longer
3. if recycled, we need fewer mines. this helps the enviroment- mining causes duast and noise pollution and damages the landscape.
4. less land is needed for land fill
5. CO2 is emitted when fossil fuels are used to heat ores or generate electricity used in electrolysis. Far less CO2 is emitted from the recycling process as less energy is needed
6. for most metals it takes less energy to melt down used metals than it does to extract from the ore. recycling is sustainable and cheaper
Uses of metals
1. metals conduct heat,and electristy.they are malleable and ductile. not all metals have exactly the same properties. the uses depend on the properties.
2. Gold
  1. used for jewellery because it looks attractive
  2. some electrical connections inside electronic devived because it is one f the best conductors.
3. Copper
  1. used for electrical cab;es because it is a very good conductor
  2. water pies- it doesnt corrode easily
4. steel
  1. used for structures because it is strong and resistant to corrosion
5. aluminium
  1. used for drinks cans- does not corrode
  2. aeroplanes and some cars it as a low density

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