1. OCR Additional Science Chemical Economics C Green CCC

2. 08/06/2016 Acids and Bases Strong acid Strong base Neutral The pH scale is a way of showing how strong or weak an acid or base is: Stomach acidLemon juiceWaterSoapOven cleanerBaking powder An “alkali” is simply a base that has been dissolved.

3. 08/06/2016 Common acids and alkalis AcidsAlkalis Hydrochloric acid, HClSodium hydroxide, NaOH Nitric acid, HNO 3 Sulphuric acid, H 2 SO 4 Potassium hydroxide, KOH Magnesium hydroxide, Mg(OH) 2 Calcium hydroxide, Ca(OH) 2

4. 08/06/2016 Neutralisation reactions When acids and alkalis react together they will NEUTRALISE each other: OH Na Sodium hydroxide Cl H Hydrochloric acid The sodium “replaces” the hydrogen from HCl Cl Na Sodium chloride H2OH2O Water General equation: Acid + base salt + water

5. 08/06/2016 Acids and Carbonates General equation: Acid + carbonate salt + water + carbon dioxide

6. 08/06/2016 Neutralisation experiment For example, in a neutralisation experiment we can mix sodium hydroxide (an _____) and hydrochloric acid together and they will ________ each other. The equation for this reaction is… Sodium hydroxide + hydrochloric acid sodium chloride + water Words – nitrate, neutralise, alkali, sulphate, salt, evaporating 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 _________

7. 08/06/2016 Neutralisation reactions The basic equation for any neutralisation reaction is: H + (aq) + OH - (aq) H 2 O (l) Write word and chemical equations for the following reactions: 1)Hydrochloric acid + sodium hydroxide 2)Hydrochloric acid + potassium hydroxide 3)Nitric acid + potassium hydroxide 4)Sulphuric acid + calcium hydroxide 5)Nitric acid + copper oxide, CuO 6)Sulphuric acid + calcium carbonate, Ca(CO) 3

8. 08/06/2016 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: Hydrochloric acid Sulphuric acidNitric acid Sodium hydroxide Sodium chloride + water Potassium hydroxide Potassium sulphate + water Calcium hydroxide Calcium nitrate + water

9. 08/06/2016 Sulphuric acid Cleaning metals Neutralising fertilisers Car batteries Uses of sulphuric acid

10. 08/06/2016 Atomic mass SYMBOL PROTON NUMBER = number of protons (obviously) RELATIVE ATOMIC MASS, A r (“Mass number”) = number of protons + number of neutrons

11. 08/06/2016 Relative formula mass, M r The relative formula mass of a compound is the relative atomic masses of all the elements in the compound added together. E.g. water H 2 O: Therefore M r for water = 16 + (2x1) = 18 Work out M r for the following compounds: 1)HCl 2)NaOH 3)MgCl 2 4)H 2 SO 4 5)K 2 CO 3 H=1, Cl=35 so M r = 36 Na=23, O=16, H=1 so M r = 40 Mg=24, Cl=35 so M r = 24+(2x35) = 94 H=1, S=32, O=16 so M r = (2x1)+32+(4x16) = 98 K=39, C=12, O=16 so M r = (2x39)+12+(3x16) = 138 Relative atomic mass of O = 16Relative atomic mass of H = 1

12. 08/06/2016 Calculating the mass of a product E.g. what mass of magnesium oxide is produced when 60g of magnesium is burned in air? Step 1: READ the equation: 2Mg + O 2 2MgO IGNORE the oxygen in step 2 – the question doesn’t ask for it Step 3: LEARN and APPLY the following 3 points: 1)48g of Mg makes 80g of MgO 2)1g of Mg makes 80/48 = 1.66g of MgO 3)60g of Mg makes 1.66 x 60 = 100g of MgO Step 2: WORK OUT the relative formula masses (M r ): 2Mg = 2 x 24 = 48 2MgO = 2 x (24+16) = 80

13. 08/06/2016 Work out M r : 2H 2 O = 2 x ((2x1)+16) = 36 2H 2 = 2x2 = 4 1.36g of water produces 4g of hydrogen 2.So 1g of water produces 4/36 = 0.11g of hydrogen 3.6g of water will produce (4/36) x 6 = 0.66g of hydrogen M r : 2Ca = 2x40 = 80 2CaO = 2 x (40+16) = 112 80g produces 112g so 10g produces (112/80) x 10 = 14g of CaO M r : 2Al 2 O 3 = 2x((2x27)+(3x16)) = 204 4Al = 4x27 = 108 204g produces 108g so 100g produces (108/204) x 100 = 52.9g of Al 2 O 3 1)When water is electrolysed it breaks down into hydrogen and oxygen: 2H 2 O 2H 2 + O 2 What mass of hydrogen is produced by the electrolysis of 6g of water? 3) What mass of aluminium is produced from 100g of aluminium oxide? 2Al 2 O 3 4Al + 3O 2 2) What mass of calcium oxide is produced when 10g of calcium burns? 2Ca + O 2 2CaO

14. 08/06/2016 Another method Try using this equation: Mass of product IN GRAMMES Mass of reactant IN GRAMMES M r of product M r of reactant Q. When water is electrolysed it breaks down into hydrogen and oxygen: 2H 2 O 2H 2 + O 2 What mass of hydrogen is produced by the electrolysis of 6g of water? Mass of product IN GRAMMES 6g 4 36 So mass of product = (4/36) x 6g = 0.66g of hydrogen

15. 08/06/2016 Percentage Yield Percentage yield = actual yield (in g) theoretical yield Example question: Theoretical yield = the amount of product that should be made as calculated from the masses of atoms Actual yield = what was actually produced in a reaction 65g of zinc reacts with 73g of hydrochloric acid and produces 102g of zinc chloride. What is the percentage yield? Zn + 2HCl ZnCl 2 + H 2

16. 08/06/2016 Percentage yield Some example questions: 1)The predicted yield of an experiment to make salt was 10g. If 7g was made what is the percentage yield? 2)Dave is trying to make water. If he predicts to make 15g but only makes 2g what is the percentage yield? 3)Sarah performs an experiment and has a percentage yield of 30%. If she made 50g what was she predicted to make? Percentage yield = Actual yield Predicted yield X 100%

17. 08/06/2016Fertilisers Fertilisers are chemicals used to help plants to grow. They contain three main elements: Nitrogen Phosphorus Potassium FertiliserChemicals used to make it Ammonium sulphateAmmonia and sulphuric acid Ammonium nitrate Ammonium phosphate Potassium nitrate

18. 08/06/2016Eutrophication Eutrophication is when lakes become stagnant due to careless use of fertiliser. There are six steps: 1) Inorganic fertilisers used on fields are washed into the lake 3) This growth causes overcrowding and many plants die due to lack of enough light or food 2) The fertiliser causes increased growth in water plants

19. 08/06/2016Eutrophication 4) Microorganisms and bacteria increase in number due to the extra dead material 5) These microorganisms use up the oxygen in the lake during respiration 6) The lack of oxygen causes the death of fish and other aquatic animals Can’t…breathe…

20. 08/06/2016Eutrophication 4) Microorganisms and bacteria increase in number due to the extra dead material 5) These microorganisms use up the oxygen in the lake during respiration 6) The lack of oxygen causes the death of fish and other aquatic animals

21. 08/06/2016 Calculating percentage mass Calculate the percentage mass of magnesium in magnesium oxide, MgO: A r for magnesium = 24Ar for oxygen = 16 M r for magnesium oxide = 24 + 16 = 40 Therefore percentage mass = 24/40 x 100% = 60% Percentage mass (%) = Mass of element A r Relative formula mass M r x100% Calculate the percentage mass of the following: 1)Hydrogen in hydrochloric acid, HCl 2)Potassium in potassium chloride, KCl 3)Calcium in calcium chloride, CaCl 2 4)Oxygen in water, H 2 O

22. 08/06/2016 Reversible Reactions Some chemical reactions are reversible. In other words, they can go in either direction: A+BC+D NH 4 ClNH 3 + HCl e.g. Ammonium chlorideAmmonia + hydrogen chloride If a reaction is EXOTHERMIC in one direction what must it be in the opposite direction? For example, consider copper sulphate: Hydrated copper sulphate (blue) Anhydrous copper sulphate (white) + Heat+ Water CuSO 4 + H 2 OCuSO 4.5H 2 O

23. 08/06/2016 Reversible Reactions When a reversible reaction occurs in a CLOSED SYSTEM (i.e. no reactants are added or taken away) an EQUILIBRIUM is achieved – in other words, the reaction goes at the same rate in both directions: A+BC+D Endothermic reactions Increased temperature: Decreased temperature: A+BC+D A+BC+D More products Less products Exothermic reactions Increased temperature: Decreased temperature: A+BC+D Less products More products A+BC+D

24. 08/06/2016 Making Ammonia Nitrogen + hydrogen Ammonia N 2 + 3H 2 2NH 3 High pressure 450 O C Iron catalyst Recycled H 2 and N 2 Nitrogen Hydrogen Mixture of NH 3, H 2 and N 2. This is cooled causing NH 3 to liquefy. Fritz Haber, 1868-1934 Guten Tag. My name is Fritz Haber and I won the Nobel Prize for chemistry. I am going to tell you how to use a reversible reaction to produce ammonia, a very important chemical. This is called the Haber Process. To produce ammonia from nitrogen and hydrogen you have to use three conditions:

25. 08/06/2016 Haber Process: The economics A while ago we looked at reversible reactions: A+BC+D Endothermic, increased temperature A+BC+D Exothermic, increase temperature ExothermicEndothermic 1) If temperature was DECREASED the amount of ammonia formed would __________... 2)However, if temperature was INCREASED the rate of reaction in both directions would ________ causing the ammonia to form faster 3)If pressure was INCREASED the amount of ammonia formed would INCREASE because there are less molecules on the right hand side of the equation Nitrogen + hydrogen Ammonia N 2 + 3H 2 2NH 3

26. 08/06/2016 The Haber Process Economics The cost of electricity/gas The cost of wages How quickly ammonia is made Cost of reactants Cost of equipment Temperature Pressure Catalyst Factors affecting the cost of making ammonia

27. 08/06/2016 Haber Process Summary 200 atm pressure 450 O C Iron catalyst Recycled H 2 and N 2 Nitrogen Hydrogen Mixture of NH 3, H 2 and N 2. This is cooled causing NH 3 to liquefy. To compromise all of these factors, these conditions are used: A low temperature increases the yield of ammonia but is too slow A high temperature improves the rate of reaction but decreases the yield too much A high pressure increases the yield of ammonia but costs a lot of money

28. 08/06/2016 Washing Powder Washing powder is a mixture and made mainly of: 1)Detergent (the bit that does the cleaning) 2)Bleach (to remove stains) 3)Water softener – to soften hard water 4)Brightener – to “whiten whites” 5)Enzymes – to digest food stains Name the symbol:

29. 08/06/2016 Washing up liquid Washing up liquid is a mixture as well and contains: 1)Detergent 2)Water (to dissolve and dilute the detergent) 3)Water softener 4)Rinse agent – to help the water “run off” 5)Colour and fragrance The detergent in washing up liquid is often a salt and made from the basic equation: Acid + alkali salt (detergent) + water

30. 08/06/2016 The structure of a detergent + Non-polar hydrophobic tail Charged hydrophilic head Detached sodium ion

31. 08/06/2016 How detergents work Oil Plate Step 1: The hydrophobic end of the detergent molecule is repelled by water, causing it to stick to the oil droplet. Step 2: As more and more detergent molecules are absorbed the oil is lifted off the plate Step 3: When it is totally surrounded the oil is washed away

32. 08/06/2016 Batch and Continuous processes In summary: ProcessBatchContinuous What it meansReactants are thrown in, the reaction happens and the batch is removed The reactants are continually fed in and the products are continually removed (e.g. the Haber Process) AdvantagesMakes a wide variety of products on demand Operate all the time and automatically, makes a large amount of product DisadvantagesMore labour intensiveCan only make one product

33. 08/06/2016 Developing new medicines The process: Step 1 - research Step 2 - development Step 3 - legalities Step 5 - marketing Step 4 - manufacture

34. 08/06/2016 Forms of Carbon 1) Diamond – very hard, doesn’t conduct electricity, very high melting point 2) Graphite – soft, does conduct electricity, very high melting point 3) Buckminsterfullerene – 60 carbon atoms arranged in a sphere

35. 08/06/2016 Forms of Carbon Choose a form of carbon and research the following: 1)What properties does this form of carbon have? 2)How are the electrons arranged in this structure? 3)How does the structure of this form affect its properties?

36. 08/06/2016Nanoscience Nanoscience is a new branch of science that refers to structures built from a few hundred atoms and are 1- 100nm big. They show different properties to the same materials in bulk. They also have a large surface area to volume ratio and their properties could lead to new developments in computers, building materials etc. Task: research nanoscience and find two current and/or future applications of this science.

37. 08/06/2016Water Amazing facts about water: 1)95% of your body mass is water (94% in women due to a higher body fat content) 2)Dinosaurs would have drunk the same water you do 3)Water dissolves more substances than any other liquid 4)Around 75% of the world’s surface is made of water 5)To feel thirsty you need to lose around 1% of your body water 6)5,000 children die every day due to not having clean drinking water 7)An average person in the West uses 200-300 litres of water every day

38. 08/06/2016Water Our drinking water comes from four main sources: rivers, lakes, reservoirs and aquifiers (wells etc). To be used as drinking water it has to be treated: The Water Treatment Process 1) Sedimentation2) Filtration3) Chlorination

39. 08/06/2016 Pollutants in water Water may contain pollutants from sources such as: 1)Old lead pipes 2)Fertiliser run off 3)Insecticides etc Allowed concentrations PollutantMaximum amount allowed Nitrates50 parts per billion Lead50 parts per billion Pesticides0.5 parts per billion

40. 08/06/2016 Dissolved ions The dissolved ions of some salts are easy to identify as they will undergo “precipitation reactions”, i.e. they will make a solid when mixed with the right substance. For each of the following reactions describe what happened, the colour of the precipitate that was formed and write a chemical reaction: 1)Sodium sulphate + barium chloride 2)Sodium chloride + silver nitrate 3)Sodium bromide + silver nitrate 4)Sodium iodide + silver nitrate

41. 08/06/2016 Using sea water Q. Given all the problems with water shortages, why can’t we just purify sea water and use it for drinking water? Research task: