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Chemistry Unit C1 – Chemistry in our World

Chemistry Unit C1 – Chemistry in our World. 20/12/2019. EdExcel. N Smith. Elements. 20/12/2019. These atoms are ALL iron – there ’ s nothing else in here. If a solid, liquid or gas is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron:.

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Chemistry Unit C1 – Chemistry in our World

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  1. Chemistry Unit C1 – Chemistry in our World 20/12/2019 EdExcel N Smith

  2. Elements 20/12/2019 These atoms are ALL iron – there’s nothing else in here If a solid, liquid or gas is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron:

  3. Compounds 20/12/2019 Sodium chloride (salt) Methane Glucose Compounds are different to elements. They contain different atoms. Here are some examples:

  4. Some simple compounds… 20/12/2019 Methane, CH4 Key Hydrogen Oxygen Carbon Sulphur Sulphuric acid, H2SO4 Carbon dioxide, CO2 Water, H2O Ethyne, C2H2

  5. Balancing equations 20/12/2019 Sodium + water sodium hydroxide + hydrogen O Na Na H H H H H O Consider the following reaction: + + This equation doesn’t balance – there are 2 hydrogen atoms on the left hand side (the “reactants” and 3 on the right hand side (the “products”)

  6. Balancing equations 20/12/2019 Sodium + water sodium hydroxide + hydrogen O O Na Na Na Na H H H H H H H H O O 2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g) We need to balance the equation: + + Now the equation is balanced, and we can write it as:

  7. Some examples 20/12/2019 Mg + O2 Zn + HCl Fe + Cl2 NaOH + HCl CH4 + O2 Ca + H2O NaOH + H2SO4 CH3OH + O2 MgO ZnCl2 + H2 FeCl3 NaCl + H2O CO2 + H2O Ca(OH)2 + H2 Na2SO4 + H2O CO2 + H2O 2 2 2 3 2 2 2 2 3 2 2 2 2 2 4

  8. Hazard signs to learn… 20/12/2019 h i Acid Corrosive Toxic Harmful Irritant Oxidising

  9. Topic 1 – The Earth’s Sea and Atmosphere 20/12/2019

  10. The Earth’s Atmosphere 20/12/2019 Carbon dioxide, water vapour Oxygen Nitrogen Noble gases For the last 200 million years the atmosphere has remained roughly the same – it contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO2

  11. Evolution of the Earth’s Atmosphere 20/12/2019 Carbon Methane Ammonia Oxygen Nitrogen Others dioxide 4 Billion years 3 Billion years 2 Billion years 1 Billion years Present day Present day atmosphere contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO2

  12. Evolution of the Earth’s Atmosphere 20/12/2019 Volcanic activity releases CO2, methane, ammonia and water vapour into the atmosphere. The water vapour condenses to form oceans. 4 Billion years 3 Billion years 2 Billion years 1 Billion years Present day Green plants evolve which take in CO2 and give out oxygen by photosynthesis, increasing the amount of oxygen in the atmosphere. Carbon from CO2 becomes locked up in sedimentary rocks as carbonates and fossil fuels and is dissolved into the sea. Methane and ammonia react with the oxygen and nitrogen is released. Some of the oxygen is converted into ozone. The ozone layer blocks out harmful ultra-violet rays which allows for the development of new life.

  13. Carbon dioxide in the atmosphere 20/12/2019 The amount of CO2 in the atmosphere is affected by 3 things: 1) Geological activity moves carbonate rocks deep into the Earth and they release ______ _______ into the atmosphere during volcanic activity. 2) Human activity - When fossil fuels are burned the carbon contained in them reacts with _____ to form CO2. Furthermore, deforestation means that less _____ are around to take in CO2. 3) Increased CO2 in the atmosphere causes a reaction between it and _______. These reactions do not remove ALL of the new CO2 so the greenhouse effect is still getting _______! Words – oxygen, seawater, carbon dioxide, worse, trees

  14. Topic 2 – Materials from the Earth 20/12/2019

  15. What are rocks? Rocks can be found here… …and here… …and here… …and here Rocks are made from a combination of minerals and can be hard or soft depending on how the minerals are arranged.

  16. Sedimentary rocks Limestone Sandstone Chalk Conglomerate

  17. Sedimentary rocks 1) Weathering 2) Transportation 3) Deposition 4) Burial How sedimentary rocks are formed:

  18. Metamorphic rocks Quartzite Slate Marble (made from chalk or limestone)

  19. Metamorphic rocks Pressure from rocks above… …and heat from magma nearby Metamorphic rocks are formed by the combined effect of heat and pressure on other rocks:

  20. Igneous rocks Obsidian Granite Pumice

  21. Igneous Rock Granite – a slow cooling rock with big crystals and rich in silica Rhyolite – a fast cooling rock with small crystals and rich in silica Gabbro – a slow cooling rock with big crystals and rich in iron Basalt – a fast cooling rock with small crystals and rich in iron

  22. Igneous rocks Igneous rocks are formed when lava or magma cools down and solidifies If the lava or magma cools QUICKLY it has SMALL crystals If the lava or magma cools SLOWLY it has BIG crystals

  23. Summary Words to use – layers, stuck, granite, marble, fossils, limestone, crystals, pressure, magma, solid

  24. Conservation of mass in reactions 20/12/2019 H H H O O O O O O O O H H C C O H O H H 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms Also 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms H Cl Mg H H Mg Cl Cl Cl H In any reaction the total mass of products is the same as the total mass of the reactants Example 1 – Magnesium oxide and hydrochloric acid Example 2 – Burning methane

  25. Calcium Carbonate Limestone Chalk Marble (made from chalk or limestone) Calcium carbonate is a common chemical in the Earth and we’ve already come across it in a number of forms:

  26. Limestone 20/12/2019 View video of limestone being quarried

  27. Limestone Limestone + sand + soda glass Limestone is a __________ rock made up of mainly calcium carbonate. It’s cheap and easy to obtain. Some uses: 1) Building materials – limestone can be quarried and cut into blocks to be used in _______. However, it is badly affected by ____ ____. 2) Glass making – glass is made by mixing limestone with _____ and soda: 3) Cement making – limestone can be “roasted” in a rotary kiln to produce dry cement. It’s then mixed with sand and gravel to make _______. Words – sand, building, sedimentary, concrete, acid rain

  28. Pros and Cons of quarrying limestone

  29. Limestone 20/12/2019 Limestone has a number of uses when it undergoes chemical reactions. There are two reactions to know: 1) Firstly, a THERMAL _________________ reaction is used to break the calcium carbonate down into calcium ______ and _______ __________: HEAT Calcium carbonate calcium oxide + carbon dioxide 2) _____ is then added to produce calcium __________: WATER Calcium oxide calcium hydroxide Words – hydroxide, decomposition, carbon dioxide, water, oxide

  30. The “Limestone Cycle” 20/12/2019 CO2 CO2 H2O H2O H2O H2O Calcium Carbonate (limestone) Step 4: add CO2 Step 1: heat Calcium Hydroxide solution Calcium Oxide Step 3: add more water and filter Step 2: add a little water Calcium Hydroxide

  31. Uses of these Calcium compounds 1) Neutralising acidic soil – calcium carbonate, calcium hydroxide and calcium oxide are _______ and can be used to ________ soil acidity to help ______ growth. 2) Removing pollutants – calcium carbonate can be used as a “_______” to remove acidic gases from a coal-fired power station’s waste products, helping prevent ____ _____. Calcium carbonate (limestone), calcium oxide and calcium hydroxide have a number of uses: Words – acid rain, alkaline, plant, scrubber, neutralise

  32. Thermal decomposition of carbonates 20/12/2019 Copper carbonate (green) turns into copper oxide (black) Limewater Limewater goes cloudy due to carbon dioxide being made Copper carbonate copper oxide + carbon dioxide Limestone undergoes thermal decomposition when heated. The same happens to other carbonates. For example, consider copper carbonate:

  33. Topic 3 – Acids 20/12/2019

  34. Neutralisation reactions Na H The sodium replaces the hydrogen from HCl Na Cl H2O Sodium chloride Water When acids and alkalis react together they will NEUTRALISE each other: Sodium hydroxide Hydrochloric acid OH Cl

  35. Neutralisation experiment Sodium hydroxide + hydrochloric acid sodium chloride + water In this experiment we mixed sodium hydroxide (an _____) and hydrochloric acid together and they ________ each other. The equation for this reaction is… • A ____ was formed during the reaction, and we could have separated this by __________ the solution. The salt that we formed depended on the acid: • Hydrochloric acid will make a CHLORIDE • Nitric acid will make a _________ • Sulphuric acid will make a _________ Words – nitrate, neutralised, alkali, sulphate, salt, evaporating

  36. Stomach Acid Hydrochloric acid is used in the stomach to help _______ and to kill ______. If we eat too many “rich” foods our stomachs create too much ____ – this is called ______. This acid needs to be neutralised by taking indigestion tablets. Indigestion tablets contain substances such as _______ that neutralise excess stomach acid. Words – digestion, indigestion, acid, alkalis, bacteria

  37. Neutralisation reactions ACID + ALKALI SALT + WATER H Cl Na Na H H O O H Cl Copy and complete the following reactions: • Sodium hydroxide + hydrochloric acid • Calcium hydroxide + hydrochloric acid • Sodium hydroxide + sulphuric acid • Magnesium hydroxide + sulphuric acid A neutralisation reaction occurs when an acid reacts with an alkali. An alkali is a metal oxide or metal hydroxide dissolved in water.

  38. Making salts Whenever an acid and alkali neutralise each other we are left with a salt, like a chloride or a sulphate. Complete the following table:

  39. Using different bases Acid + metal oxide natural salt solution + water H2SO4(aq) + CuO(s) CuSO4(s) + H2O(l) heat heat Suphuric acid + copper oxide copper sulphate + water Acid + metal carbonate natural salt soln + water + CO2 heat Sulphuric acid + calcium carbonate calcium sulphate + water + CO2 H2SO4(aq) + CaCO3(s) CaSO4(aq) + + H20(l) + CO2(g) heat A metal oxide base: A metal carbonate base:

  40. Reactions of metals carbonates with acid METAL CARBONATE + ACID SALT + CARBON DIOXIDE + WATER Mg H Cl Cl Mg H H C C Cl H Cl O O O O O O Copy and complete the following reactions: • Magnesium carbonate + hydrochloric acid • Calcium carbonate + hydrochloric acid • Sodium carbonate + sulphuric acid A metal carbonate is a compound containing a metal, carbon and oxygen.

  41. Reactions of metal oxides with acid Al Na Mg Na Al Magnesium oxide Sodium oxide Aluminium oxide METAL OXIDE + ACID SALT + WATER O O O O O O O H Cl Mg H H Mg Cl Cl Cl H Copy and complete the following reactions: • Magnesium oxide + hydrochloric acid • Calcium oxide + hydrochloric acid • Sodium oxide + sulphuric acid A metal oxide is a compound containing a metal and oxide. They are sometimes called BASES. For example:

  42. Electrolysis of Hydrochloric Acid ++++ ---- Positive electrode Negative electrode Hydrochloric acid Cl- Cl- Cl- H+ H+ H+

  43. Testing for Hydrogen “POP”

  44. Testing for Chlorine Chlorine “bleaches” damp indicator paper. It is also a toxic gas so don’t breathe it! This leads to problems when it comes to large-scale manufacture of chlorine gas.

  45. Electrolysis of seawater Chlorine gas (Cl2) Hydrogen gas (H2) Sodium chloride solution (seawater) NaCl(aq) Sodium hydroxide (NaOH(aq)) Positive electrode Negative electrode Seawater is a mixture of water and salt (sodium chloride) and we can electrolyse it to produce chlorine and other useful products:

  46. Uses of chlorine Cl Cl H H C C C C H H H H Polyvinylchloride (PVC) Chloroethene monomer Lots more Chloroethene monomers H H H H C C C C H H H H Polyvinylchloride (PVC) is made up of lots of monomers of vinyl chloride (chloroethene): Chlorine is also used in the manufacture of bleach. Sodium hydroxide is reacted with chlorine to form sodium hypochlorite (bleach): • Cl2 + 2 NaOH → NaCl + NaClO + H2O

  47. Electrolysis of Water O H H Oxygen gas (O2) Hydrogen gas (H2) Water H2O Positive electrode Negative electrode Water is two atoms of hydrogen and one atom of oxygen. It can be electrolysed to break it down:

  48. Testing for Oxygen Oxygen will relight a glowing splint

  49. Topic 4 – Obtaining and Using Metals 20/12/2019

  50. Extracting Metals 20/12/2019 Oxide Iron Some definitions: A METAL ORE is a mineral or mixture of minerals from which it is “economically viable” to extract some metal. Most ores contain METAL OXIDES (e.g. rust = iron oxide). To “extract” a metal from a metal oxide we need to REDUCE the oxygen. This is called a REDUCTION reaction. To put it simply: Iron ore “Reduce” the oxygen to make iron

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