science gcse core, additional and triple powerpoints

1. C6 Chemical synthesis Route map Over the next 12 lessons you will study : Friday 21 October 2011 C6.1 The chemical industry C6.2 Acids and alkalis C6.3 Reactions of acids C6.4 Salts from acids End of module test C6.5 Salts in our lives C6.6 Purity of chemicals C6.7 Rates of reactions C6.8 Factors affecting rates of reactions C6.9 Catalyst in industry C6.10 Chemical quantities ? C6.11 Stages in chemical synthesis C6.12 Measuring the yield

3. C6.1 The chemical industry Decide whether the following statements are true or false: Introduction: The chemical industry uses raw materials such as crude oil, natural gas, minerals, air, air and water to produce useful products. The bulk chemicals such as ammonia, sulphuric acid, sodium hydroxide, chlorine and ethene are produces in a large scale, whereas fine chemicals such as drugs, pesticides, food additives and liquids crystals for flat-screen TV and computer screens are produced in a smaller scale. The part of a chemical work that produces a chemical is called a plant. People such as researches, chemists are needed in the industry. The industry needs to use smaller amounts of raw materials and energy, while creating les waste, so the whole process is sustainable. Extension questions: 1: Give three examples of bulk chemicals ? 2: What are fine chemicals ? Give three examples of them ? 3: Give an example of a) a fuel b) a dye or paint c) a fibre d) an agrochemical and e) a plastic ? 4: What raw material do we use to produce a) petrol b) plastics and c) chlorine gas ? 5: How can the chemical industry be a) more green in what it does and more sustainable in what raw materials it uses ? Know this: a: Know that the chemical industry produces thousands of tonnes per year of bulk and fine chemicals. b: Know that the chemical industry is very important as it supply bulk and fine chemical to make finished produces such as dyes, drugs fuels, plastic and fibres Friday 21 October 2011

4. C6.1 a Look at the photograph and information and answer all the questions: The chemical industry comprises the companies that produce industrial chemicals. It is central to modern world economy, converting raw materials (oil, natural gas, air, water, metals, minerals) into more than 70,000 different products. The largest corporate producers worldwide, with plants in numerous countries, are BASF, Shell, Bayer, ExxonMobil, DuPont and BP. Name three companies that produce fuels and lubricants ? Name the company that produces a) fibre optics b) Viagra and c) Gortex ? Name a company that produces a) a dye b) a prescribed drug c) a polymer and d) bulk chemicals ? Key concepts

5. Key concepts C6.1 b Look at the photograph and information and answer all the questions: Name the raw materials that make a) fuels b) fibres c) metals and d) plastics ? Explain the difference between a synthetic compound and a natural compound and give one example of each ? We use chemicals to preserve food, treat disease, and decorate our homes. Many of these chemicals are synthetic. Developing new products, such as drugs to treat disease depend on the chemists who synthesize and test new chemicals. People devising new products have to work closely with in the marketing and sales department. They are able to say if the new product is wanted and whether it will make money. The chemical industry Raw materials Finished products

6. Look at the photograph and information and answer all the questions: Crude oil into finished products crude oil Give two uses of the following polymers a) polythene b) cotton c) plastic d) Nylon and e) polystyrene ? PVC a synthetic polymer is used to make window and door frames...give three advantages to using PVC when compared to using natural materials like wood ? Plastics have a very short life cycle and normally disposed of after one use. Plastic no biodegrade and can fill landfill. Why is this a problem for us of ? C6.1 c raw material products Crude oil is a very important raw material. Extracted from deep underground, crude oil is a mixture or very long and short chain hydrocarbons containing the elements hydrogen and carbon. These organic molecules can be used to make bulk chemicals like fuels and plastics and fine chemicals like drugs and dye stuffs. Key concepts

7. C6.1 Plenary Friday 21 October 2011 The chemical industry converts raw materials into pure chemicals which are then used in synthesis to make a wide range of products. People with many different skills are needed in the industry. Research chemist work in laboratories to find new processes and develop new products. Marketing industry tell chemist if their product is wanted. How Science Works: Research about acids and alkalis, the pH scale and the production and use of sulphuric acid H 2 SO 4 in the chemical industry Preparing for the next lesson: The raw materials for the ______industry come from mines, farms, forests, seas, air, oil and gas wells. They are converted into pure chemicals such as acids, _____, salts, solvents, and organic compounds, called ____chemicals or fine chemicals such as ______, pesticides, dyes and agrochemicals. Lesson summary: alkaline chemical aspirin bulk Decide whether the following statements are true or false : False True 3: Bulk chemicals are produced on a scale of thousands of tones per year ? False True 2: Ethene used to make polythene is a fine chemical ? False True 1: Crude oil is a raw material used in chemical industry to make fuels like petrol ?

9. C6.2 Acids and alkalis Friday 21 October 2011 Extension questions: 1: What are acids ? Give two examples of mineral and two of organic acids. Write their formulae down. 2: What is the pH of a weak acid and a weak base ? 3: What is the pH of a strong acid and strong base ? 4: What are alkalis ? Give three examples of alkalis. Write their formulae down. 5: List three properties of acids and three properties of alkalis ? Know this: a: Know the properties and uses of acid and alkalis in the chemical industry b: Know that strong acids and alkies are corrosive and some common alkalis are sodium hydroxide, NaOH , potassium hydroxide, KOH, calcium hydroxide Ca(OH) 2 Introduction: Acids are compounds that dissolve in water and give pH of lower than 7. Some common acids that we use in the lab are sulphuric acid (H 2 SO 4 ) . hydrochloric acid (HCl), and nitric acid (HNO 3 ) . These acids come from inorganic or mineral sources. Sulphuric and nitric acid are liquid at room temperature. Hydrogen chloride is a gas which dissolves in water and becomes hydrochloric acid. Organic acids such as acetic acid CH 3 COOH or vinegar and citric acid C 6 H 8 O 7 ( in lemons), are not dangerous and are used to preserve food. Alkalis are soluble bases with a pH of more than 7. Bases are usually; Metal hydroxides containing the OH- ion, Ammonia which contains NO 3 - and Carbonates which contains CO 3 2- Ion.

10. C6.2 a Look at the photograph and information and answer all the questions: The pH scale is a way of telling us whether a a substance is acidic, neutral or alkaline. Liquids like lemon and tomato juice are acidic. Pure water is neutral and liquids like toothpaste and oven cleaner are alkaline. pH can also tell us how strong an acid or alkaline is, for example strong acids have a pH of 1, strong alkalis have a pH of 13. Give two examples of a substance that is strongly acidic and two examples of substance that are strongly alkaline ? Explain why all toothpastes are made slightly alkaline with a pH of 8 ? A lake has become acidic due to acid rain...explain how you could obtain the lake water’s pH and how would you bring the lake water’s pH back to near neutral ? Key concepts pH 2 pH 3 pH 4 pH 5 pH 6 pH 1 pH 7 pH 12 pH 11 pH 10 pH 9 pH 8 pH 13 pH 7 Battery acid Vinegar Urine Lemon juice Acid rain Tomato juice Pure water Caustic soda Oven cleaner Toothpaste Bleach Baking soda Soapy water Pure water Acids Alkalis

11. C6.2 b Look at the photograph and information and answer all the questions: Acids are chemicals with very high amounts of hydrogen ions. They will turn litmus paper red. They will also have a pH ranging from 1 to 6 when tested using universal indicator. Acids will also attack materials like metals liberating hydrogen gas and forming a metal salt. Acids are found naturally and have a sour taste, for example lemon juice is rich in citric acid. You have two liquids, both are acids. The pH of liquid A is 2 and the pH of liquid B is 6.5...explain which is the strongest acid ? Explain how the acids contained in vinegar preserve foods like pickled onions over long periods of time ? You spill hydrochloric acid on your skin and clothes...what safety precautions should you have taken and what should you do ? pH 2 pH 3 pH 4 pH 5 pH 6 pH 1 pH 7 Battery acid Vinegar Urine Lemon juice Acid rain Tomato juice Pure water Acids and pH Key concepts

12. C6.2 c Look at the photograph and information and answer all the questions: Alkalis are the opposite of acids. They have very low amounts of hydrogen ions. They will turn litmus paper blue. They will also have a pH ranging from 8 to 13 when tested using universal indicator. Alkalis are caustic and can cause very severe skin burns. This is because they attack the fat layer below the skin epidermis. Take care using sodium hydroxide because it is very caustic. pH 12 pH 11 pH 10 pH 9 pH 8 pH 13 pH 7 Caustic soda Oven cleaner Toothpaste Bleach Baking soda Soapy water Pure water You have two liquids both are alkalis. The pH of liquid A is 7.5 and the pH of liquid B is 8.0..explain which is the strongest alkaline ? Alkalis (bases) and pH Explain why many toothpastes now contain small amounts of baking soda ? All alkalis feel ‘soapy’ that’s because they are reacting with the fats in your skin cells and damaging your skin. What should you do if you spill an alkaline on your skin ? Key concepts

13. Key concepts C6.2 d Look at the photograph and information and answer all the questions: Give three properties of acids and give three uses of acids at home or at work ? Sulphuric acid is used to manufacture dyes, fertilisers and plastics, Explain the importance of these three bulk chemicals ? Sulphuric acid is made in three steps. Stage 1 Sulphur is heated until it melts. The liquid sulphur is burnt in air, where it forms make sulphur dioxide gas. Stage 2 The sulphur dioxide gas is mixed with more air and heated. The sulphur dioxide reacts with oxygen to make sulphur trioxide. Stage 3 Sulphur trioxide gas dissolves in water to make sulphuric acid. In industry, this gas is dissolved in very strong sulphuric acid, making it even stronger Making sulphuric acid Sulphuric acid: H 2 SO 4

14. C6.2 Plenary Lesson summary: concentrated neutralising HNO 3 citric Friday 21 October 2011 Strong mineral acids like HCl and H 2 SO 4 are dangerous. They are diluted and handled with care. Organic acids are useful and used in the food industry. Strong alkalis such as sodium hydroxide are very corrosive and even more dangerous to living tissues then acids because they attack the fat layer deep underneath your epidermal layer causing heavy scaring. These are used in most of the cleaning products including degreasers for example Mr. Muscle. How Science Works: Research about the properties of acid and alkies, what the pH scale means and how acids react with metals, metal oxides and metal carbonates. Preparing for the next lesson: Acids such as H 2 SO 4 , HCl, _____are corrosive and dangerous if_______. Organic acids such as ethonoic and _______acid are part of life itself. Alkalis are soluble bases with a pH more then 7. Pharmacists use alkalis in ‘antacids’ tablets to control heartburn and indigestion by _________the access acid in stomach. Decide whether the following statements are true or false : False True 3: Sulphuric acid has the formula HCl ? False True 2: Alkalis feel soapy to the touch and have a pH above 7 ? False True 1: All acids are dangerous and corrosive ?

16. Friday 21 October 2011 C6.3 Extension questions: 1: What is a salt ? 2: Name the following salts from their formulae a) NaCl b) CuSO 4 c) Cu(NO 3 ) 2 d) KCl e) MgCl 2 f) CaSO 4 g) Na 2 SO 4 and h) Na 2 CO 3 ? 3: Give one way of making a salt in a laboratory ? 4: Give the formulae of the following salts a) Iron sulphate b) Silver nitrate c) Magnesium nitrate and d) Copper chloride ? 5: If you add an acid to a soluble base, how could you tell the reaction had finished ? Know this: a: Know the properties of acid and their pH. b: Know that a salt is formed when an acid reacts with a metal, a metal oxide and a metal carbonate. Reaction of acids Introduction: The pH scale is used to check the acidity or the alkalinity of a solution. Metals salts are formed during the reactions of acids with metals, metal oxides and carbonates. During the formation of a metal salt, the reaction mixture ends with a neutral pH of 7. Common examples of reactions with acids: metal + acid salt + hydrogen metal hydroxide + acid salt + water metal carbonate + acid salt + carbon dioxide + water metal oxide + acid salt + water

17. C6.3 a Look at the photograph and information and answer all the questions: Why should you never ‘taste an acid’ and why should you use pH paper ? Why are acids not stored in metal containers and what should you do if you spill acid on a) the bench and b) your skin ? Common properties of acids: 1. They are solutions of compounds in water. 2. If concentrated they can be corrosive. 3. Acids taste sour (for example, vinegar). 4. Turn blue litmus paper red - this is an easy test for an acid! 5. Usually react with metals to form salts. 6. Acids contain hydrogen ions. 7. Turn Universal Indicator from green to red, and have a pH less than 7. Examples: Hydrochloric acid, sulphuric acid, citric acid, nitric acid and acetic acid corrosive taste sour turns litmus paper red dissolves in water contains H+ ions Properties of acids pH of 1 to 6 Key concepts

18. C6.3 b Look at the photograph and information and answer all the questions: Why should you never ‘taste an acid’ and why should you use pH paper ? Why are acids not stored in metal containers and what should you do if you spill acid on a) the bench and b) your skin ? Common properties of alkalis 1. They feel soapy to touch. 2. They are soluble bases. 3. Like acids, they can burn the skin. 4. They turn red litmus blue - this is how you test for an alkali! 5. Alkalis contain hydroxide ions (OH-). 6. They taste bitter. 7. Turns Universal Indicator from green to blue or purple. Examples: Sodium hydroxide, NaOH (aq) Ammonia, NH 3 NH 4 OH(aq) feel soapy to touch corrosive turns litmus paper blue solutions in water contains OH- ions Properties of bases pH of 8 to 14 NaOH Key concepts

19. C6.3 c Look at the photograph and information and answer all the questions: Reactive metals like calcium, magnesium and zinc will readily react with hydrochloric acid librating hydrogen gas whilst forming the metal chloride salt. Un-reactive metals like gold, silver and copper will not react with laboratory acids. Hydrogen is the fuel for all stars and could be used in hydrogen fuel cells to power cars of the future ! Explain why foods like pickled onions and gherkins which are preserved in acidic vinegar are not stored in metal cans ? What is the test for hydrogen gas and predict whether silver will react with hydrochloric acid ? Gold Copper Iron Zinc Magnesium No reaction in acid Reaction in acid Give a word and symbol equation for the reactions between a) Magnesium (Mg) and hydrochloric acid (HCl) and b) Copper (Cu) and sulphuric acid (H 2 SO 4 ) ? Key concepts Battery acid Vinegar Urine Lemon juice Acid rain Tomato juice Pure water pH 2 pH 3 pH 4 pH 5 pH 6 pH 1 pH 7

20. Key concepts C6.3 d Look at the photograph and information and answer all the questions: Reactions of acids Metal oxides like copper oxide (CuO) are basic and when added to mineral acids like hydrochloric acid (HCl) or sulphuric acid (H 2 SO 4 ) will form a metal salt and water. Metal carbonates like Magnesium carbonate (MgCO 3 ) are also basic and when added to mineral acid like sulphuric acid with form three products. The metal salt. Carbon dioxide gas and water. Write a general equation for the reaction between a metal oxide and an acid ? Write a word and a symbol equation for the reaction between zinc oxide (ZnO) and a) Hydrochloric acid (HCl) b) Sulphuric acid (H 2 SO 4 ) and c) Nitric acid (HNO 3 ) ? Copper Oxide Sulphuric Copper Sulphate Water Copper Oxide Hydrochloric Copper Chloride Water Copper Oxide Nitric Copper Nitrate Water Metal Oxide Acid Metal salt Product Sodium carbonate Hydrochloric Sodium Chloride CO 2 + H 2 O Calcium carbonate Sulphuric Calcium Sulphate Metal carbonate Acid Magnesium carbonate Nitric Magnesium nitrate CO 2 + H 2 O CO 2 + H 2 O Metal salt Product

21. C6.3 Plenary Lesson summary: Decide whether the following statements are true or false : False True 3: Taking the pH using a data logger is less accurate than using pH paper ? False True 2: Acids will react with bases to form a salt and water ? False True 1: Distilled water has a pH of 9 ? 8 and 14 soapy metals salt There are many examples of neutralisation reactions that happen at home for example in the kitchen or bathroom. Toothpaste is alkaline with a pH or about 8 and neutralises acids produced by bacteria found on your tooth’s surface. Acids erode tooth enamel and cause tooth decay. How Science Works: Friday 21 October 2011 Preparing for the next lesson: Research into what makes an acid and acid, the difference between a strong and a weak acid and how salts are formed during a neutralisation reaction between an acid and a base. Acids have a pH of between 1 and 6, are corrosive and can react with _______ and metal compounds. Alkalis can feel _____ to the touch are also corrosive and have a pH of between _______. An acid and an alkalis added together will form a _____ and water during neutralisation.

23. C6.4 Salts from acids Extension questions: 1: Ethane contain hydrogen, but it doesn't produce H + when dissolves in water. Is ethane C 2 H 6 acid ? 2: Write a ionic equation of sulphuric acid : H 2 SO 4, in water ? 3: What are the ions that are produced when calcium hydroxide Ca(OH) 2 is dissolved in water ? 4: Write the formula of calcium chloride, magnesium nitrate, potassium hydroxide ? Know this: a: Know that acids always produce hydrogen ions (H + ) in water and a non-metal negative ion: HCl produces Cl – chloride ion, H 2 SO 4 produces SO 4 2– , sulphate ion, HNO 3. produces NO 3 – , nitrate ion Friday 21 October 2011 Introduction: An acid is a compound that dissolves in water and produces positive hydrogen ions (H+). All acids have hydrogen in their formula but not all chemicals containing H 2 are acids. Alkalis are soluble bases that when dissolve in water give negative hydroxide ions. During a neutralisation reaction the hydrogen ion from an acid reacts with hydroxide ions from the alkali and make water. The remaining ions in the solution make a salt: HCl H + + Cl - NaOH Na + + OH - H + + Cl - + Na + + OH - NaCl + H 2 O

24. Key concepts Look at the photograph and information and answer all the questions: Give the details of a test to tell the difference between a very strong and a very weak acid ? Why are weak organic acid often used in cooking ? In strong mineral acids like hydrochloric acid, sulphuric acid and nitric acids, when in solution many H+ or hydrogen ions are generated. These ions attack metals, metal oxides and metal carbonates. In organic acids, the number of hydrogen ions that are found away form the main part of the acid is much lower which is why they are weak acids . H 2 SO 4 CH 3 COOH strong acid Strong and weak acids strong acid C6.4 a

25. Key concepts Look at the photograph and information and answer all the questions: A salt is any compound which can be derived from the neutralization of an acid and a base. The word "neutralization" is used because the acid and base properties of H + and OH - are destroyed or neutralized. In the reaction, H + and OH - combine to form HOH or H 2 O or water molecules. A salt is the product of an acid-base reaction and is a much broader term then common table salt as shown in the first reaction. strong acid Neutralisation between an acid and base salt and water strong alkali HCl NaOH C6.4 b Write a word equation form the symbol equation of the following examples of neutralization reactions to form salts. a. HCl + NaOH NaCl + HOH b. H 2 SO 4 + 2NH 4 OH (NH 4 ) 2 SO 4 + 2H 2 O c. CaCO 3 + 2HCl CaCl 2 + CO 2 + H 2 O Na + Na + Na + Na + H + H + HCl HCl H 2 O H 2 O OH - OH - OH - NaCl H 2 O NaCl H 2 O NaCl H 2 O NaCl H 2 O

26. C6.4 a Look at the photograph and information and answer all the questions: Metal oxides like copper oxide (CuO) are basic and when added to acids like hydrochloric acid or sulphuric acid will form a metal salt and water. When an acid and a soluble base react they neutralise one another. The pH of an acid is 1 at the start and the pH of the base is 14. At the end of the reaction, the mixture of metal salt and water is neutral with a pH of 7. Write a general equation for the reaction between a metal oxide and an acid ? Give two other examples where neutralisation takes place, for example toothpaste neutralising tooth acid ? Write a word and a symbol equation for the reaction between zinc oxide (ZnO) and a) Hydrochloric acid (HCl) b) Sulphuric acid (H 2 SO 4 ) and c) Nitric acid (HNO 3 ) ? 100% acid 100% base Neutralisation Neutralisation titration Metal Oxide Metal oxides with acids Acid Metal salt and other product Copper Oxide Sulphuric Copper Sulphate Water Copper Oxide Hydrochloric Copper Chloride Water Copper Oxide Nitric Copper Nitrate Water Sodium Oxide Hydrochloric Sodium Chloride Water Calcium Oxide Sulphuric Calcium Sulphate Water Key concepts

27. Plenary Lesson summary: hydroxide water hydrogen sodium A solution of hydrochloric acid contains _______ions and chloride ions. A solution of sodium ________contains _______ions and hydroxide ions . Hydroxide ions in an alkaline solution react with hydrogen ions in an acid solution to make _________ molecules. This is neutralization. How Science Works: Friday 21 October 2011 Research into the chemical and physical properties of salts and some of their uses Preparing for the next lesson: Knowing about neutralisation and what is an acid and what is an alkaline or soluble base is extremely useful. If stung by a wasp neutralise with an acid like lemon juice or vinegar. If stung by a bee neutralise with an alkaline like baking soda or even toothpaste. Done get it the wrong way round or it will hurt even more. C6.4 Decide whether the following statements are true or false : False True 3: Alkali dissolve in water and produce negative hydroxide ion? False True 2: Acids dissolve in water and produce negative hydrogen ions? False True 1: All compounds containing hydrogen are acids ?

29. Decide whether the following statements are true or false: Friday 21 October 2011 C6.5 Salts in our lives Extension questions: 1: Write a balanced equation for the reaction between calcium and water. ? 2: Write a balanced equation for the reaction between hydrochloric acid and calcium oxide ? 3: Why is it important to purify calcium chloride used in dialyses ? 4: What are the processes involved in the purification of calcium chloride ? 5: Name three other salts and give a use for each ? Know this: a: Know some use and properties of salts. b: Know that calcium chloride used during kidney dialysis is purified by using many processes such as: filtration, evaporation and crystallisation. Introduction: The reactions of acids with metals, oxides, hydroxides and carbonates can be used to make valuable salts. We use in our daily lives salts that come from lithosphere. For uses such as food and medicine this salts must be purified. People with kidney failure has to remove the toxic chemicals from their blood through a dialysis machine. One of the salts used in the dialyses is calcium chloride. It is important that the level of calcium in blood has to maintained at a particular level and the patient will be very ill if there is little changes. The calcium chloride has to very pure and the quantity added to the solution has to be measured accurately.

30. Key concepts Look at the photograph and information and answer all the questions: Meats like bacon, pork salami are preserved using both salt and potassium nitrate. The potassium nitrate prevents harmful very bacteria like botulism forming on the surface of the meat. Before using potassium nitrates, only salt was used to preserve bacon. This meant that people who are bacon were at risk form botulism. Why is it not a good idea just to use table salt or NaCl to preserve foods like bacon and salami ? Which is the parent acid to produce potassium nitrate? Write the formula of the acid and the salt C6.5 a KNO 3 KNO 3 NaCl NaCl NaCl KNO 3 Preserving meat using sodium chloride and potassium nitrate

31. Key concepts Look at the photograph and information and answer all the questions: Inside the kidney dialysis machine, the blood is pumped over the dialysis membrane. Urea and other chemicals diffuse across the membrane and are removed from the blood. The dialysis fluid contains amino acids and glucose to prevent your sugars and amino acids leaving the blood. The cleaned blood is then pumped back into the body . unclean blood clean blood Vein Artery dialysis fluid in dialysis fluid out urea excess salt calcium chloride C6.5 b Give three substances in the blood that are removed during kidney dialysis ? Explain why the calcium chloride used during dialysis has to be both pure and sterile ? Using calcium chloride during Kidney dialysis

32. Key concepts Look at the photograph and information and answer all the questions: Inside the kidney dialysis machine, the blood is pumped over the dialysis membrane. Urea and other chemicals diffuse across the membrane and are removed from the blood. The dialysis fluid contains amino acids and glucose to prevent your sugars and amino acids leaving the blood. The cleaned blood is then pumped back into the body . C6.5 c Explain how a) filtering and b) crystallising help improve the purity of the CaCl 2 compound ? What type of reaction occurs when calcium hydroxide Ca(OH) 2 reacts with Hydrochloric acid (HCl) ? Manufacturing and purifying calcium chloride (CaCl 2 ) Limestone (CaCO 3 ) is quarried The CaCO 3 is heated forming CaO The CaO is added to water to make Ca(OH) 2 The CaCl 2 is now purified prior to dialysis Ca(OH) 2 is reacted with HCl formingCaCl 2 CaCl 2 is filtered to remove impure solids CaCl 2 is then concentrated forming crystals Pure crystals of CaCl 2 are dried and then used

33. C6.5 Plenary Lesson summary: KNO 3 s alts chloride calcium Friday 21 October 2011 Limestone is baked and mixed with water to make calcium hydroxide. Calcium hydroxide is mixed with hydrochloric acid to produce calcium chloride. The solution is filtered, concentrated by evaporation and crystals are produced. The crystals are dried, paced and labelled. How Science Works: Research into how important ensuring that fine chemicals including drugs are free from impurities Preparing for the next lesson: Soluble salts are present in many areas of our lives. Metal _____ like sodium ______NaCl, potassium nitrate ______, potassium chloride KCl, and ______ chloride CaCl 2 , are extremely important. Very pure calcium chloride is used in the dialysis machines. Decide whether the following statements are true or false : False True 3: Calcium chloride is produced by reacting calcium oxide and hydrochloric acid ? False True 2: Potassium chloride is used in fire works ? False True 1: Potassium nitrate is used to curing meat like bacon ?

35. Decide whether the following statements are true or false: Friday 21 October 2011 Extension questions: 1: What type of reaction is used in a titration technique ? 2: How can we decide which grade of purity to use ? 3: Why is expensive to get high purity of chemicals ? 4: Why is titration used to purify citric acid ? 5: Why is important to check the purity of calcium carbonate in an indigestion tablet ? 6: Explain why purity is not important for salt used to grit roads ? Know this: a: Know what chemical purity means and know that titration uses neutralization reaction to check the purity of acids. b: Know that at each stage of a synthesis process a product can be purified, however each purification stage takes time and money. Introduction: It is important to check the purity of chemicals used, especially fine chemicals used to make prescription drugs e.g. calcium carbonate in a indigestion tablet. There are different grades used to check the purity of chemicals: analytical, technical, general, and laboratory. The purest is the analytical grade. The grade used is dependant of: the amount of impurities, what the impurities are, how can they effect the process, whether they will end up in the product. Titration is an analytical technique used to find out accurately how much of a chemical substance is dissolved in a given volume of a solution. The aim is to make sure that all chemicals are between 99%-100% pure. C6.6 Purity of chemicals

36. Key concepts Look at the photograph and information and answer all the questions: Despite existing at very low levels, contaminants in none pure substances like prescription drugs or even the water we drink can have subtle yet significant effects. Purity is mostly determined by the raw material, the manufacturing method and subsequent handling procedures. Special precautions must be taken at all stages of manufacture to maintain high purity. Very pure substances are more expensive to produce. C6.6 a Explain why 100% purity in any chemical is almost impossible to achieve ? Give three impurities found in normal drinking water that supplies our homes and schools ? Purity in chemistry Pure water ? Pure CuSO 4

37. Look at the photograph and information and answer all the questions: Explain why using a data logger and pH probe is a more accurate method to monitor the reaction between an acid and a soluble base ? Explain why the first titration volume is not included when you calculate the average for the titration experiment ? Quantitative titration Citric Acid 25cm 3 of soluble base + indicator Titrating volume 1 st titration 2 nd titration 3 rd titration 4 th titration Volume cm 3 7cm 3 6.8cm 3 6.7cm 3 6.7cm 3 Average 6.73cm 3 Before a bulk or fine chemical is sold it must be graded for purity. Citric acid is added to many products to increase the levels of vitamin C. Scientists will check the purity of the citric acid (Vitamin C) using titration. When reacting an acid like citric acid with a base we can monitor the pH of the neutralisation reaction by using a pH probe connected to a data logger or a chemical indicator which changes colour. At the moment when neutralisation occurs, the pH of the mixture will be exactly 7. It is always important to do a rough titration and then three more where the volume should not be more than 0.1cm 3 apart from each other C6.6 b Key concepts

38. Look at the photograph and information and answer all the questions: Give one reason why the company made false claims about the quantity of Vitamin C in their soft drink ? Think of another two products (drinks, cleaning fluids e.t.c.) that could be tested using titration analysis ? Two New Zealand schoolgirls humbled one of the world's biggest food and drugs companies after their school science experiment found that Ribena contained almost no trace of vitamin C. Students Anna Devathasan and Jenny Suo tested the amount of vitamin C (citric acid) using titration and found that despite the company claiming that their drink contained 4 times the amount of Vitamin C when compared to orange juice it contain only trace amounts. As a result of the titration by the schoolgirls, the company was fined large amount of money. Ribena and the vitamin C scandal Anna Devathasan and Jenny Suo C6.6 c Key concepts

39. Key concepts Look at the photograph and information and answer all the questions: Explain why when doing a titration, you have to a) reduce the influence of error sand b) estimate the level of accuracy in any experiment ? Explain why when using an indicator it is difficult to make a precise judgement when end point is reached ? In any titration there are parts of the experiment where errors are made usually based on accuracy and the precision of equipment used. An accuracy error might be for example does the glassware allow you to measure volume to 0.1 cm 3 or 0.5cm 3 . An precision error might be do you have three set of data for the same experiment close to each other or is there a large spread in the data. Precision and accuracy of a acid-base titration Is the burette accurate, are readings precise ? Are solutions the right concentration ? Is the indicator accurate ? Is the titration data reliable ? C6.6 d

40. C6.6 Plenary Lesson summary: purity substances titration exact Friday 21 October 2011 Substances have impurities in them. Chemists decide what grade of chemical to use knowing: the amount of impurities, what the impurities are, how they can affect the process, and if they will end up in the product. The technicians check the purity before they use chemical or sell chemical like drugs and other finished products to the general public. How Science Works: Research into rates of reaction, how scientists measure the rate of a reaction and what factors affect how quick substrates react with one another to form new products. Preparing for the next lesson: There are many _______used to make a synthetic chemical. It is important to check the _____of each substance before it is used. This is done to make sure that the _______amount of a particular substance is the chemical. _______is an analytical technique used to measure the purity of a sample. Decide whether the following statements are true or false : False True 3: At the end point the acid is neutralised by the alkali so it has a pH of zero ? False True 2: A burette is a type of measuring balance ? False True 1: Purifying chemicals is a long process that is done in stages ?