science gcse core, additional and triple powerpoints

1. C7 Chemistry ‘triple science’ Route map Over the next 24 lessons you will study : Friday 21 October 2011 C7.1 The alkanes C7.2 The alcohols C7.3 Carboxylic acids C7.4 Esters End of module test C7.5 Fats and oils C7.7 Energy changes C7.15 Chromatography C7.16 Interpretating chromatograms C7.17 Gas chromatography C7.18 Titrations C7.8 How much energy C7.9 How fast...rates of reaction C7.10 Reversible changes C7.11 Equilibrium C7.19 Precision and accuracy C7.20 Overview of the chemical industry C7.21 Green chemistry C7.22 Improving yield in industrial chemistry C7.12 Theories on acidity C7.13 Stages in analysis C7.23 Making industrial chemistry greener C7.24 Reducing waste in industrial chemistry C7.6 fats and human health C7.14 Sampling C7.25 Using by-products and reducing waste C7.26 Making ethanoic acid

3. Extension questions: 1: Explain why the ample is vaporised before it moves through the separating column ? 2: Explain why the coiled separating column is placed inside a heated oven ? 3: If a sample is injected and it produces three peaks at different times, what can you conclude about this sample ? 4: Another sample is injected and it produces one peak only, what can you say about this sample ? Know this: a: Know how gas chromatography works to separate complex mixtures. b: Know how the retention time for a compound arises. Friday 21 October 2011 Introduction: Gas chromatography separates our complex mixtures of chemicals based on the time taken for a compound to travel through the column. The process involves a sample being vapourised and injected onto the head of the column. The sample is then transported through the column by the flow of inert, gaseous mobile phase. The column itself contains a liquid stationary phase. If a sample contains a mixture of different compounds they will be separated out and a detector records a ‘peak’ which is a record of how long the compound took to pass through the column. The height of the peak tells us how much of the compound is present. C7.17 Gas chromatography

4. Key concepts C7.17 a Look at the photograph and information and answer all the questions: In a typical gas chromatograph the sample to be analysed is introduced by a syringe into the hot flowing carrier gas. The sample vaporises immediately and the analysis proceeds by repeated transfer of the components to the stationary phase and back to the gas again. The more strongly a substance is adsorbed or the more soluble it is in the liquid film, the more slowly it moves through the column. Give one similarity between gas chromatography and thin layer chromatography ? Explain how you could use gas chromatography to check the quality oif drinking water ? Look at the diagram below left, how many components have been separated from left to right ? Modern gas chromatography Gas chromatography column chromatography column (retention time)

5. Key concepts C7.17 b Look at the photograph and information and answer all the questions: Why is the column a) coiled and b) heated by the oven ? Look at the chromatogram in the diagram what is the retention time (approx of the highest and smallest peak ? The carrier gas (mobile phase) must be chemically inert. Commonly used gases include nitrogen, helium, argon, and carbon dioxide. When the carrier gas and sample mixture travel through the column (stationary inert phase) they begin to separate out. Most packed columns are 1.5 - 10m in length and have an internal diameter of 2 - 4mm. The separated out molecules are then detected and shown as peaks on a computer trace carrier gas sample oven column detector readout trace Overview of gas chromatography

6. Key concepts C7.17 c Look at the photograph and information and answer all the questions: Compare the retention times for the reference same and the athlete’s blood sample. Has he taken any banned drugs and which ones if you have answered yes ? Give two other uses for gas chromatography other than testing athletes blood for banned drugs ? At the end of the column is a detector which signals when a separated out molecule (from the original sample) is leaving the column. It also provides a measure of the amount of the compound present. The diagram opposite left shows a typical trace for 6 different compounds. Each compound has its own unique retention time. As with HPLC compounds are generally identified by the time (after injection) that they take to reach the detector (the retention time) when conditions are carefully controlled. This means that pure samples of all likely compounds in the mixture must be available 0 2 4 6 normal 37 o C time days Recorder response o 0 50 100 0 2 4 6 normal 37 o C time days Recorder response o 0 50 100 Athletes blood sample Reference drug sample adrenaline steroid EPO urea 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10

7. C7.17 Plenary Lesson summary: separate mobile injected column Friday 21 October 2011 The smallest gas chromatography device was sent recently to planet Mars on a probe that main purpose was to find molecules that would show evidence of life such as proteins, DNA or even simple waste products like urea. So far no positive results have shown evidence of life on planet Mars . How Science Works: Research into titrations and how this technique is used to determine the concentrations of an acid or alkaline of unknown solutions. Preparing for the next lesson: In gas chromatography, the carrier gas, also known as the _______ phase is mixed with the sample mixture and __________ into the ________ . When different molecules in the sample begin to ____________ out as they travel through the column they are read by a detector and recorded using a computer. Decide whether the following statements are true or false : False True 3: Thin layer chromatography is more effective at separating complex mixtures ? False True 2: Each compound appears as a distinct peak in the chromatogram ? False True 1: Using gas chromatograms we can detect illegal drugs like steroids ?

9. C7.18 Extension questions: 1: Explain why a) an indicator is used during a titration b) the volume of acid is measured using an accurate burette c) the titration is repeated two or three times d) an errors in the data are repeated ? 2: If one litre of a 1 molar solution of sodium hydroxide solution contained 40 grams of sodium hydroxide a) what would 0.5 litre of a 0.5 M solution of NaOH contain b) 2 litres of 0.25 M NaOH contain ? 3: Explain what this statement means. The accuracy of a titration can be no more accurate than the accuracy of the solutions used ? Know this: a: Know that a titrations a quantitative technique. b: Know that titrations can determine the concentration of an unknown solution. Friday 21 October 2011 Introduction: Titration is a quantitative technique to investigate the unknown concentration or quantity of a dissolved solute that will react with an acid or alkaline. In a titration the pipette is used to transfer a fixed volume (normally 25 cm 3 ) of a solution of unknown concentration into a conical flask. Another solution with a known concentration is carefully added from a burette until it has all exactly reacted. This is called the end point of the titration. An indicator tell us when the end point is reached. The titration is repeated until successive titres are within 0.1 cm 3 . Using equation for the reaction the concentration of the unknown solution can be calculated. Titration

10. C7.18 a 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 Key concepts 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 A typical titration allows you to determine the concentration of an acid or base. When reacting an acid with a soluble 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. In the reaction shown opposite left, acid is being added to the base. 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

11. Key concepts C7.18 a 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

12. C7.18 Plenary Lesson summary: quantity precise indicator endpoint Friday 21 October 2011 Titrations are highly accurate quantitative methods to determine the concentration of an unknown acid or basic solution. In order to be precise, accurate and reliable. Chemists take great care in choosing accurate equipment, reducing the possibility of errors and ensuring reliability by repeating their titrations at least three times. How Science Works: Research into reliability accuracy and precision of data generated during an experiment or analytical method used by scientists. Preparing for the next lesson: A titration is a ________ of analysis that will allow you to determine the precise __________ of a reaction and therefore the precise _________ of reactant in the titration flask. A burette is used to deliver the second reactant to the flask and an __________ or pH meter is used to detect the endpoint of the reaction. Decide whether the following statements are true or false : False True 3: Usually an acid titrated a base until an endpoint is reached ? False True 2: Using a burette instead of measuring cylinder makes the data more precise ? False True 1: Repeated titrations make your data more reliable ?

14. Extension questions: 1: Give two pieces of equipment that are a) accurate b) precise c) neither accurate or precise ? 2: Which is the more precise a thermometer with 0.1 o C or 0.5 o C between its scale ? 3: Explain what is a systematic error and which is more reliable a set of results that his an average of five or three readings ? 5: Which is a more accurate method of measuring liquids, a conical flask or a graduated burette ? Know this: a: Know the difference between precision, accuracy and data reliability. b: Know that in any experiment there are errors that need to be controlled and minimised. Friday 21 October 2011 Introduction: As scientists, it is important to be sure that the data we are collecting is accurate, precise and reliable. If not, we may not be confident about our findings. In some cases errors in our data can also cost lives. There is always uncertainty (also known as ‘error’) for any measured or calculated value. This does not refer to mistakes, but rather unavoidable error due to the nature of the experiment or the equipment we use. Chemists work very hard to reduce error and improve data accuracy, precision and reliability. C7.19 Precision, reliability and accuracy of data

15. Key concepts C7.19 a Look at the photograph and information and answer all the questions: Which is the more accurate balance a) balance one which measure to 0.1g or b) balance two which measure to 0.01g ? Which is more reliable a) a average which is the results of two reading or b) an avarge which is the result of 10 readings ? Accuracy, precision and reliability are three of the most misunderstood terms in science. Many times people talk about one of the terms when they are really expressing the thoughts contained in the other. 1: Accuracy describes how close a result, reading or measurement is to the actual value. 2: Precision is a measure of the spread of measured values. A large spread means a greater uncertainty than does a small spread. 3: Reliability describes how repeatable a particular result or set of results are. precise but not accurate accurate but not precise not precise not accurate accurate and precise Precision and accuracy

16. Key concepts C7.19 b Look at the photograph and information and answer all the questions: Accuracy: if you were measuring the width of a grape using a ruler, you might report a value of 12.3 mm but there would definitely be some error incorporated in that last digit. Precision: if you measured temperature with a thermometer with a manufacturers claimed accuracy to within 0.1º C. This means that the precision of the thermometer is only 0.1 o C. Similarly, balances found in school laboratories are usually only accurate to within 0.1 g or 0.01 g. During an experiment a teacher offered you either a) an accurate balance, accurate thermometer and a inaccurate timer or b) an inaccurate balance, inaccurate thermometer and a accurate timer. Which would you chose and why in order to ensure that your experiment contain the least errors ? Precision and accuracy in experiments what level of accuracy does the timer measure time ? what level of accuracy does the thermometer measure temperature ? are the solution used during the experiment the right volume and concentration what level of accuracy does the balance measure mass ? are the substrates used during the experiment to the right mass and purity

17. Key concepts C7.19 c 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 ?

18. C7.19 Plenary Lesson summary: wrong actual error bias Friday 21 October 2011 Leyland who used to make the mini car before the government sold it off to German owned BMW, miscalculated the cost of making the mini. They priced the mini below what it actually cost them to make meaning that the company never made a profit and the taxpayer had to bail them out. This was a very long and expensive mistake. (BMW have not repeated this error and make a very good profit !) How Science Works: Research into green chemistry and how chemists are helping to provide solutions that are environmental friendly from biodegradable plastics to improves fuels that reduce emissions of greenhouse gases. Preparing for the next lesson: Accuracy is how close a measured value is to the _______ (true) value. Precision is how close you can measure to the actual value. When doing experiments, there is also ______ or a systematic ______. Bias is a systematic (built in) error which makes all measurements _______ by a certain amount . Decide whether the following statements are true or false : False True 3: When you miss the bulls eye that dart you have thrown was accurate ? False True 2: A conical flask is less precise than a burette for measuring volumes ? False True 1: A set of weighing scales that doesn’t zero has a bias or systematic error ?

21. Key concepts C7.20 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 ?

22. Key concepts C7.20 b Look at the photograph and information and answer all the questions: It very easy to overlook the importance of German industrial scientist Fritz Haber’s industrial process of making ammonia form nitrogen and hydrogen. Ammonia is the raw material used to manufacture fertilisers. Without fertiliser, our populations in developed countries would crash. Using fertiliser increases crop yield by 200 to 300 percent ! Explain why the Haber process is so important to people living in the industrialised World ? Explain where the nitrogen, one of the raw materials to make ammonia is sourced ? The reaction between nitrogen and hydrogen only proceeds at 400 to 500 o C. Why does this make the Haber process expensive ?

23. Key concepts C7.20 b Look at the photograph and information and answer all the questions: In order to separate out the different fractions, crude oil is heated to about 400 o C. Explain why this is done in an oxygen free environment ? Which fraction do you think is in highest demand and which is in lowest demand ? An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as petrol, diesel fuel, bitumen, heating oil, paraffin, and liquefied petroleum gas. Oil refineries are typically large sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units. C1 – C4 C5 – C10 C10 – C12 C12 – C16 C16 – C30 C30 – C100 C100 – C300 < 40 o C 40 o C – 200 o C 175 o C – 275 o C 235 o C – 300 o C >300 o C > 350 o C Highly flammable gas fuel Car fuel (petrol) Valuable source of organic molecules Aviation fuel Larger vehicle fuels (diesel) lubricants 125 o C – 175 o C Bitumen. Used to lay roads. Overview of crude oil fractional distillation

24. Plenary Lesson summary: oils refining reactions products Friday 21 October 2011 Crude oil perhaps the most value ever raw material is a naturally occurring, toxic, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights, and other organic compounds, that are found in geologic formations beneath the Earth's surface. We currently use about 80 million barrels every day. How Science Works: Research into how the chemical industry is trying to become more environmentally friendly in how it manufactures products to the products it makes. Preparing for the next lesson: The chemical industry involves the use of chemical processes such as chemical __________ and ______ methods to produce a wide variety of products used directly (solvents, pesticides, washing soda, and cement) and indirectly including, petro and agro-chemicals, polymers and rubber, _____, explosives, fragrances and flavours . C7.20 Decide whether the following statements are true or false : False True 3: Metal ores are used to manufacture metals like iron and aluminium ? False True 2: Often water, raw material and energy are required for industrial processes ? False True 1: Crude oil is a source of fuels, lubricants and plastics ?

26. Extension questions: 1: State which of the following raw materials are renewable or non-renewable a) crude oil b) wood c) cotton fibres d) glass and e) plastic ? 2: Compare the environmental impact of using a paper versus a plastic versus a cotton bag (think of the raw material used during its manufacture, its life expectancy and how we recycle or landfill it ? 3: Give three examples of chemical industries polluting the a) the soil b) the atmosphere and c) drinking water ? 4: Explain why chemical companies want a green image ? Know this: a: Know how to ensure that the products and how chemists make them are environmentally friendly. b: Know how to improve yields, reduce waste and energy consumption during a product’s manufacture. Friday 21 October 2011 Introduction: Green Industry is producing environment friendly products or products or technology which can directly help the environment. Many businesses and chemists work very hard to ensure that a process of a finished product cause minimal damage to environment. Green chemistry where possible uses renewable natural raw materials, minimal amounts of energy for manufacture, transport and storage and ensure that the product has a long life expectancy of use and when no longer required by the consumer can be partially or fully recycled. C7.21 Green chemistry

27. Look at the photograph and information and answer all the questions: Key concepts Using crude oil raw material ethene polythene products crude oil The word polymer literally means &quot;many parts.&quot; A polymer contains many units or monomers which are joined together to form a long chain. Polymers can be man made or naturally occurring like cotton, silk or even human hair. Three of the best know polymers used widely are nylon, rubber and polythene. Except rubber, these are synthetic polymers made in factories. 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 ? C7.21 a

29. Look at the photograph and information and answer all the questions: The word polymer literally means &quot;many parts.&quot; A polymer contains many units or monomers which are joined together to form a long chain. Polymers can be man made or naturally occurring like cotton, silk or even human hair. Three of the best know polymers used widely are nylon, rubber and polythene. Except rubber, these are synthetic polymers made in factories. 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 ? Key concepts Products that use synthetic polymers Neoprene Kevlar Latex PET polythene HD PVC LD PVC C7.21 c

30. Plenary Lesson summary: short food waste natural Friday 21 October 2011 Enjoy synthetic polymers while you can ! The raw materials and the source of entry to make these polymers is of course crude oil. With only 50 years of supply left, in your life time you may be one of the last person to use a polythene bag to carry your shopping home from the supermarket. How Science Works: Research into ‘is it better and more environmentally friendly to use paper or china plates on a daily basis Preparing for the next lesson: Most plastics used in the _____ industry and a very _____ life cycle and contribute up to 8% of our domestic _____ that is taken to landfill sites across the country. Such a short life cycle is a waste of our _________ resources and our energy. C7.21 Decide whether the following statements are true or false : False True 3: In landfill sites, plastic take many centuries to rot and decompose ? False True 2: When crude oil runs out, bulk polythene manufacture will cease ? False True 1: A bag made from cotton which can be reused is environmentally friendly ?