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Metals and their properties and reactivity Summary report Aim: To investigate the properties and reactivity of various metals. Background Society has many metals at its disposal. Why are metals important and why is a particular metal chosen for a particular product? Summary report with annotations Your report could include:

• the results obtained from Part A, Part B and Part C. You need to choose a suitable format for these results.

• what you have learnt about the properties of metals • comments on the design of these three experiments • discussion of whether the properties of metals are consistent • discussion of how the theory of metals impacts upon their particular uses in

society • explanation of the relationship between the properties of metals and the

electron configuration. • explanation of the relationship between properties of a metal and position on

the periodic table. • rules for predicting the reactivity of metals.

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Assessment Rubric for summary report. Aspect Excellent

Good Low Negligible

Experimental procedure

Proper safety procedures followed. Materials handled carefully. Mats used. Samples kept discrete

General sound experimental procedures exhibited.

Medium attention to safety and to experimental procedures

Unsafe practices. Chemicals contaminated. Equipment used incorrectly.

Recording of results

Clear notes taken in a folder. Tables used where appropriate. Correct chemical symbols and units

Good record of results. Good use of units.

Results available but not presented clearly.

Confusing records of results. Poor design of tables.

Relationships between metals and other aspects of chemistry

Many correct connections provided between metals and other aspects of chemistry

Several connections made with other concepts

Some connections made with other concepts.

Few connections, or incorrect connections, made.

Connections made to uses of metals in society

Many connections made between theory and the uses of metals.

Several connections made with metals in society.

Some connections made with the uses of metals.

Few connections, or incorrect connections, made.

Correct chemical terms and equations

Correct chemical terminology and correct symbols used on all occasions.

Good use of terms and symbols.

Some incorrect terms used.

Frequent incorrect terminology evident. Incorrect symbols used.

Conclusion

Key evidence from different experiments tied together. Clear knowledge of concepts covered evident.

Knowledge of most key concepts evident.

Some knowledge evident but poor links between experimental data and conclusions.

Key knowledge not evident.

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Metals and their properties and reactivity Summary report Aim: To investigate the properties and reactivity of various metals. Background Society has many metals at its disposal. Why are metals important and why is a particular metal chosen for a particular product? Part A: Properties of METALS AIM: To - familiarise students with a range of common metals and their properties

- investigate reactivity differences in metals Method Several work stations have been set up around the room. Rotate to each station until you have all four tasks completed. Appearance Examine samples of each metal provided. Record your observations in a table like the one shown Metal Name Colour Appearance Melting point Other

properties

Density Density can be calculated from the formula, d=m m= mass (g), v= volume (ml) V Use the apparatus provided, measuring cylinder and balance, to calculate the density of each metal sample. Fill in the table provided. Metal mass g volume ml density g/ml

Hardness Decide upon a simple test for hardness. Describe this test and use it to rank the metals in order of hardness. Melting point Heat samples of each metal in a fume cupboard. Rank those that melt in order of melting point.

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Questions that might aid discussion 1. What properties do metals seem to exhibit? 2. Do all metals behave the same? 3. Does the density of metals vary much? Can you think of examples where the mass

of metals is significant i.e. lead fishing sinkers 4. Why was sodium not included in the metals to be tested? 5. Can you see any connection between position on the Periodic Table and properties

of the metal? 6. Where in fact on the Periodic Table are all of the metals? Part B Reactivity Aim: To compare the reactivity of metals Method Your teacher will demonstrate the reaction of sodium and potassium in water. Place a sample of each other metal in a beaker containing 2M sulfuric acid. Rank each metal according to its reactivity. Metal Symbol Observation Ranking

Write a balanced for the reaction between sodium and water. How can you use pH paper to verify your reaction? Does it matter what acid is used? Try a different one, Part C Displacement reactions. Aim: To harness our knowledge of the different reactivities of metals. Method: Add a small piece of zinc to a solution of copper sulfate. Add a small piece of copper to zinc sulfate. What do you notice between the reactions? Compare the reactivity ranking that you gave to each metal. Write an equation for the reaction that occurs. Repeat the procedure with magnesium and zinc. Can you form a rule for predicting which metals will react in which solutions? Prove your rule using a different combination. Link your results to position on the Periodic Table. Link your results to uses of metals in society.

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Water Analysis Extended Experimental Analysis

Aim: To perform a series of experiments that lead to an analysis of a sample of water. Background The quality of our water supplies is of significant interest in modern society. Reasons for this include agriculture, swimming and human consumption. Most large cities have a water board that can perform standard tests on water samples. The typical substances or organism that are tested for include acidity, salt, phosphorous, bacteria, micro-organisms, dissolved oxygen and metals. The table below summarises some typical tests conducted on water.

Test Method Reason for testing Turbidity Coloured disk (Sechi

disk) lowered into the water.

Measure of water clarity. Suspended solids can affect the amount of light reaching submerged plants

pH pH paper or pH meter or Universal Indicator

pH is usually between 6.5 and 8.5. High acidity is damaging to aquatic life. Alkaline conditions can be caused by soaps or fertilizers.

Undissolved solids Filtration and gravimetric Mud, silt and solid discharges Dissolved solids Filtration then

evaporation or conductivity

Often related to salinity or water hardness. Mostly ionic substances

Salinity Precipitation or conductivity

Plant growth is affected by salinity. Aquatic life is also.

Dissolved oxygen Winkler titration or colorimetric

Many organisms require oxygen but, if the levels are too high, algae will flourish at the expense of other aquatic life.

Micro-organisms Filter and grow on agar plates in an incubator

The presence of animal waste can be determined this way. A range of other possible protozoa, algae, larvae and bacteria are possible.

Phosphate Acid digestion and colorimetric

Test for agricultural run-off and domestic sewage.

Task To test a sample of water and to summarise the composition of that sample. Your analysis should address each of the following;

• Where was your sample taken from? • What sampling technique did you use? • Experiments conducted

- What is the test for? - What method was used? Did you have to modify the procedure? - Results obtained.

• Breakdown of the composition of your sample. • Conclusion.

This is an investigation. A discussion of the suitability, or modification, of your procedure can be as important as the results.

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Experimental Procedures Turbidity Cut out an 8 cm diameter cardboard disk. Colour half of the top red and half black in non water soluble pen or paint. Make a hole in the middle and thread a knotted twine through the hole. Blu-tack a small weight to the bottom so that the cardboard will sink in water. Lower the disk into your water supply until the disk is no longer visible. The depth that this occurs at is a measure of the turbidity of the water. pH Use one of the following to test pH of your sample – pH probe, Universal Indicator solution or pH paper. If you are using pH paper, the low range paper should lead to better results. Perhaps compare the pH obtained from all three methods. Undissolved solids Weigh a filter paper. Filter a set volume of water, 100 mL for example. Dry the filter paper. Reweigh. Calculate the %m/v of undissolved solids. Dissolved solids Filter a set volume of water. Retain the filtered water. Weigh an evaporating basin. Add a set volume of the filtered water to the evaporating basin. Boil the water away. Reweigh the evaporating basin. Calculate the %m/v of dissolved solids. Try a flame test of the solid residue. Does the flame test hint at the presence of any particular metal? Salinity A Write a balanced equation for the reaction between sodium chloride and silver nitrate. Add 25 mL of 0.1 M silver nitrate solution to 25 mL of your water sample. Weigh a filter paper. Filter the sample. Dry the filter paper and reweigh. Calculate the number of mole of silver chloride. Calculate the number of mole of sodium chloride that must have been present. Calculate the concentration of the salt. Salinity B Salt is ionic. As a solution it will conduct. Perhaps the salinity levels can be calculated from the conductivity level of a solution. Prepare a series of low concentration salt solutions. Test their conductivity using platinum or graphite electrodes and an ammeter. Can a useful calibration curve be prepared from your data? Why should you not run the circuit for very long? Can you measure the salinity of your sample using this technique?

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Micro-organisms Examine a few drops of your sample under a microscope, looking for any small creatures. There is a wide range of possible organisms, larvae, algae, invertebrates included. You will need reference books to identify examples. Filter a sample of water. Prepare some nutrient agar to add to petri dishes. 7 g per 250 mL of nutrient agar. Allow to set with a lid on the dish. Use a sterile loop to stain an agar plate with your sample. Hold the lid of the petri dish open enough to stain the agar. Place the loop in your water sample and quickly spread it over the surface of the agar. Close the lid. Keep a control plate of agar for comparison. Add the petri dishes to an incubator and incubate at 35 0C for 1- 2 days. Examine the petri dishes for colonies of organisms. The number of colonies can actually be counted. To do this, prepare a series of dilutions of your original sample. Stain each of these. When they have developed, you will need to examine them from most concentrated to least. When you get to one that the colonies can actually be conted on, do this and multiply by the dilution factor.

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Acid/Base Indicator Annotated Experiment Report Aim: To extract and test an acid/base indicator. Background There are many substances that can act as acid/base indicators. In this experiment you will extract and test some indicators. You will ascertain if the colour changes of these indicators are consistent and whether they change colour at the same pH. Acid/base indicators are usually weak acids. When the molecule donates a proton in a chemical reaction, it changes colour. Report Your report will include;

• A concise description of the experiments that you conducted. These will include

- the extraction of potential indicators - testing of these indicators - a titration using one of the indicators.

• The results that you obtained. • Annotations that explain the theory evident in your experiments and the links

that you can make to other aspects of Unit 1 and 2 Chemistry. (Note: A formal experiment report with Aim: Method: etc is NOT required for each experiment. Emphasis is on the links that you can make between the different experiments and other aspects of the course.) Indicator Extraction Flower petals, red cabbage and brown tea are examples of substances that contain acid/base indicators. Select examples of these or other parts of a plant or other substances that you wish to test. Add the substance (flower petals for example) to a 30 mL of a 50:50 mixture of water and methylated spirits in a 250 mL flask. Heat gently on a hot plate for about 5 minutes. Allow to cool. Pour off the liquid. Repeat for at least two other potential indicators. Testing of indicators How can you test if your liquids are acid/base indicators? See if your experimenting works. Are the colour changes consistent? Discard the liquids that do not work. Are there any conclusions that you can make? pH of colour change For those indicators that work, do they all change colour at the same pH? This procedure is to find the pH range of your indicator. You might have to vary the procedure suggested here, depending upon the behaviour of your indicator. Add 5 mL of 0.05 M sodium carbonate to a 100 mL beaker.

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Add 15 mL of water. Add a pH probe to monitor the pH. Add about 10 drops of your indicator. Add 0.05 M ethanoic acid drop by drop to the beaker, stirring carefully in between. Record the pH at which a colour change seems to start and the pH at which it seems to finish. Compare results to other members of the class. Titration Use your indicator for a titration between 0.1 M hydrochloric acid and a solution of sodium hydroxide of unknown concentration. Also conduct the titration with phenolphthalein as an indicator. How do the two endpoints compare? How do the concentrations obtained for the sodium hydroxide compare? Footnote: The summary report could include discussion of what indicators are and how consistent their properties are. Indicators are weak acids; what is a weak acid and why are they significant? How does the indicator allow a titration to occur and why might the results differ with the indicator. This task could be suitable as an extended experimental investigation as each step along the way lends itself to experimental design and variations in procedure.

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Properties of water Annotated Experiment Report Aim: To determine the properties of water through experimentation. Background Water is a very common substance that we tend to take for granted. It is however, a chemical like many others that we study. Not only that, it has some very interesting and unique properties. This series of experiments should highlight many of these properties. Report Your report will include;

• A concise description of the experiments that you conducted. • The results that you obtained. • Annotations that explain the properties of water that are responsible for the

observations and measurements that you have made. • Discussion of instances in nature of where the properties of water that you are

investigating are significant. (Note: A formal experiment report with Aim: Method: etc is NOT required for each experiment. Emphasis is on the linking of experimental data to the properties of water) Preliminary discussion Draw a molecule of water. Describe, using a sketch, the bonding between neighbouring water molecules. Part A: Density of Ice compared to Water Aim: To determine and compare the density of ice and water. Possible method Weigh a 10ml measuring cylinder Add about 8ml of water. Record the exact volume. Weigh the cylinder and contents. Freeze Record the new volume. Question 1. Do you need to reweigh the cylinder? Calculate the density of water. Calculate the density of ice. Part B: Heating Curve Aim: To learn more about the properties of water through heating a sample. Setup a bunsen and tripod. Add 50 mL of water to a 100 mL beaker of water. Record the temperature. Start heating the beaker and record the temperature every 30 secs.

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Stir well before each reading. (Temperature readings could be taken with a temperature probe.) Allow the water to boil for 10 minutes before turning the bunsen off. Check the volume remaining in the beaker. Draw a temperature –time graph of the results. Temp Questions 1. At what temperature did some bubbles first appear? 2. At what temperature did the water boil? time 3. Where does boiling seem to take place? 4. What is the shape of the graph as the water is heated? 5. Does it seem to take the same amount of energy to raise the temperature from 20

to 25 0C as it does to take the temperature from 80 to 85 0C. Justify your answer. 6. Does it take more energy to heat water or to boil water away?

Part C Boiling Point In A Vacuum - Teacher demonstration Aim: To demonstrate the impact of air pressure on boiling point. (Wear safety glasses) Add about 200 mL of water to a 500 mL florence flask. Fit the florence flask with a rubber stopper with two holes. Fit a thermometer in one hole. It must fit tightly. Vacuum grease can help. Fit a short length of glass tubing through the other hole with a short length of clear tubing on it. The tubing should have a clamp on it but the clamp starts in a loose position. Heat the flask on a Bunsen or hot plate until it is boiling and steam is escaping. Remove the flask from the heat source. Do the clamp up so that no further steam can escape. Allow the flask to cool for a few minutes. When you invert the flask and place a wet cloth on the flask, the water will boil. This effect will continue even when the temperature drops under 80 0C. Question What is the lowest temperature you were able to get the water to boil at? Part D Freezing Point Aim: To investigate the freezing point of water. Add some ice from a cold freezer to a 1 litre beaker. Add a little water and about 200g of table salt. Stir.

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Record the temperature of the water and monitor the temperature over the next 10 minutes. What other observation can you make? Question 1. What is the lowest temperature at which water still exists as a liquid? Part E Specific heat capacity Aim: To compare the rate at which different liquids respond to heat. Add 30 mL of oil to a 100 mL beaker. Add 30 mL of water to another and 30 mL of ethanol to a third. Place a thermometer in each. Wait until each liquid has the same temperature. Sit all beakers on the same hot plate and turn it on. Record the temperature in each beaker every 30 seconds. Stop heating when the first liquid starts to boil. Sketch a temperature vs time graph to compare the heating curve for each liquid. (It would be possible to use a calorimeter attached to a power supply, and a voltmeter and an ammeter, to obtain a value for the specific heat capacity of water.)

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Investigating Bonding Annotated Experiment Report Aim: To conduct experiments that will provide evidence on the structure of a range of solids. Background In most chemistry courses substances are classified into categories according to their chemical structures. Information on chemical structure is usually obtained through experimentation. Report Your report will include;

• A concise description of the experiments that you conducted. • The results that you obtained. • Annotations that explain what each experiment teaches you about the

substances that you are testing. • Discussion of how the properties of the substances studied lead to their

particular uses in society. • Generalisations about the properties of different categories of solids.

(Note: A formal experiment report with Aim: Method: etc is NOT required for each experiment. Emphasis is on the linking of experimental data to the structure of the substances) Preliminary discussion Substances to be studied could include tin, lithium chloride, sugar, benzoic acid, sulfur, copper sulfate. The teacher might choose to label the substances with a letter or number and to not provide their name. In this way students cannot easily use preconceptions about properties. These experiments do not have to be conducted in the same week. Each experiment could be introduced throughout semester one as the relevant theory is introduced. Part A: Examination Aim: To observe each substance under a microscope. Examine a sample of each substance under a microscope or hand lens. Draw the structure of each. What observations can you make? Part B: Properties Aim: To investigate some of the properties of these substances. Electrical conductivity. Set up a simple circuit that contains a light globe. Use each substance to try and complete the circuit. Which materials conduct? Ductility. If particles of each substance are placed on a flat surface and struck with a hammer. What happens? Density and solubility. Add a sample of each material to water. Is it denser than water? Is it soluble in water?

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Flammability and flame colour. Use a flame test wire loop to place a small sample of each in a flame. Is the material flammable? Does it have a particular flame colour? Part C: Observations on heating Aim: To observe each substance carefully as it is heated. Place a small sample of a substance in an ignition tube. Introduce the ignition tube to a Bunsen flame carefully. Heat gently at first. Observe any changes. If no change occurs, heat strongly. Allow the tube to cool. Repeat for each substance. Examine each substance once it has cooled to see if any change was permanent. Part D: Conductivity in water Aim: To test the conductivity of each substance in water. Add a sample of a substance to water. Stir. Test the conductivity of the liquid. Repeat for each substance. Assessment of Key Skills Key Skill High Medium Low Not

shown responsible and safe work practice

collect, process and record data, draw conclusions

construct questions, identify uncertainty, design issues

apply ethics of scientific research

make connections between concepts, process information

demonstrate how theory has evolved over time

analyse issues for science

relate information to public opinion

interpret, explain and communicate information

communication suitable for different audiences

use scientific language and conventions correctly

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Assessment Rubric for Investigative bonding task. Aspect Excellent

Good Low Negligible

Independence with experimenting

No assistance required. Initiative shown.

Initiative shown. Some assistance sought

Some initiative but significant assistance requested

Experiments not completed or constant direction required.

Experimental procedure

Proper safety procedures followed. Materials handled carefully. Mats used. Samples kept discrete

General sound experimental procedures exhibited.

Medium attention to safety and to experimental procedures

Unsafe practices. Chemicals contaminated. Equipment used incorrectly.

Recording of results

Clear notes taken in a folder. Tables used where appropriate. Correct chemical symbols and units

Good record of results. Good use of units.

Results available but not presented clearly.

Confusing records of results. Poor design of tables.

Choice of results to report upon

Results indicate a clear recognition of what results are important.

Most important data has been recorded.

Results shown but some key data missing.

Important data not shown. Results not reflecting upon the aims of the task.

Correct chemical terms

Correct chemical terminology and correct symbols used on all occasions.

Good use of terms and symbols.

Some incorrect terms used.

Frequent incorrect terminology evident. Incorrect symbols used.

Conclusion

Key evidence from different experiments tied together. Clear knowledge of concepts covered evident.

Knowledge of most key concepts evident.

Some knowledge evident but poor links between experimental data and conclusions.

Key knowledge not evident.

Obtaining a numerical grade? 3,2,1,0 applied to each column

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Oxygen gas Extended Experimental Analysis

Aim: To perform a series of experiments relating to the production and testing of oxygen gas. Background One of the gases of the atmosphere is oxygen. In the laboratory, oxygen can be produced through a variety of means. Some of its properties can be tested easily. At this stage of the course, students should be able to write balanced equations for the reactions involved and they should be able to predict masses and volumes of gases produced. Part A: Manufacture using hydrogen peroxide. Add about 15 mL of 20 volume hydrogen peroxide to a large test tube. The test tube should have a single holed stopper with rubber tubing. Set up an upside down gas jar for collecting the oxygen via water displacement. Add a spatula of manganese dioxide to the test tube and quickly insert the stopper. Collect a sample of oxygen. Manganese dioxide is a catalyst for this reaction. Write an equation for this reaction. Part B: Testing of oxygen gas Some typical tests for oxygen include

• plunging a glowing splint into the gas • plunging red hot steel wool into the gas • adding burning sulfur on a deflagrating spoon.

Write balanced equations for the reactions that you are conducting. How did early scientists like Sir Humphry Davy test oxygen? Part C: Manufacture using potassium permanganate Oxygen can be produced in a similar fashion to Part A by heating a sample of solid potassium permanganate in the test tube. Write a balanced equation for this reaction. Use the balanced equation to predict the mass of potassium permanganate required to produce 80 mL of oxygen gas in a gas syringe. Test your prediction using a gas syringe. The solubility of oxygen in water could be tested by collecting a sample of oxygen in a gas syringe and a sample in an inverted measuring cylinder that had been filled with water. Do equal volumes of water form in both cases? Part D: Manufacture through electrolysis of water – teacher demonstration A Hoffman voltammeter or similar apparatus can be used to break water up into hydrogen and oxygen. Write a balanced equation for this reaction.

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Electrolyse a sample of water. Investigate the gases produced and their respective volumes. Part E: Manufacture in plants Investigate placing a bag filled with carbon dioxide over a plant or branch of a plant for a few days. Does the flammability of the gas in the bag increase with time? Part F: Research How is oxygen produced commercially? The history of the discovery of oxygen is a very interesting topic to research. Conductivity of liquids Data analysis Aims: To measure the conductivity of a series of liquids. To use a knowledge of chemical bonding to explain the recorded conductivities. Task: Students are to test the conductivity of the following liquids; ethanol, tap water, distilled water, salt solution, sugar solution, calcium carbonate suspension. Students could prepare the salt, sugar and calcium carbonate samples themselves. Conductivity could be testes with a simple circuit using a power supply, an ammeter and carbon electrodes. A multi-meter could also be used. Do not run the circuits for long periods of time. Results: Present results in the form of a table. Use a column of your results table to write in the ‘category’ that the material belongs to i.e. ionic. A The liquids to be tested are listed in Table 1 below. For each liquid, predict whether it will conduct or not. Questions 1. For each material, use a sketch to explain carefully the conductivity or lack of conductivity. 2. What conclusions can you draw? 3. Do all ionic solutions conduct equally? 4. Why do you not run the circuits for long periods of time?

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Investigations of cells Summary report with annotations Aim: To investigate the chemistry of galvanic cells (batteries). Background: Our supermarkets contain many batteries. They power the increasing range of portable appliances available to society. This set of experiments investigates the requirements necessary to produce an electric current and the variables that impact upon that current. Part A: Batteries What things are necessary to make a battery? Do you understand what an electric circuit is? You are supplied with a lemon and an ammeter. Can you create an electrical circuit? You may need to ask for other pieces of equipment. Draw your circuit. What things help the current obtained? Part B: Cell Voltages Aim: To investigate the variables that affect the voltage produced in a cell Set up the cell shown below and record the voltage. Zn V Cu 0.1 M NaCl The magnitude of the voltage that you have produced probably depends upon many factors. The aim of this experiment is for you to predict what some of these factors might be and for you to evaluate each. Use the table provided to list possible variables that might affect the voltage produced i.e. distance between electrodes. Outline in column 2 how you might evaluate each of these variables.

Variable

How to test the variable Results

Distance between

electrodes

Set up the circuit in a large beaker and gradually increase

separation of electrodes

Voltage did not change at all unless electrodes

touched

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Conduct each of your tests and place your results in column 3. Conclusion List the variables that will affect your voltage and those that do not. Part C: Redox VoltageTable Aim: To compare the voltages produced by different ½ cells To generate a table from these voltages that can be used for predicting reactions. Background Different metal combinations produce different voltages. If these voltages are compared under standard conditions, a useful table of values can be generated. What steps should you take to 'standardise' conditions? Method You are supplied with a Cu/Cu(s) ½ cell. Several other metal ½ cells are available on the front bench. You will take the ½ cells one at a time from the front bench and connect them to the copper ½ cell. Use a fresh salt bridge each time. For the first cell chosen, what polarity did you have to make the copper for the voltage to be a positive one? Electrons travel to the positive electrode from the negative electrode. Write a ½ equation for the copper electrode that reflects this electron flow. Write a ½ equation for the other metal. Write an overall equation. Repeat the procedure for each of the ½ cells provided and record the voltage and the polarity. Results

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Represent your results using a table of voltages. Rank the metals in order of voltage. Now use the voltages that you recorded to give each of the metals in your ranking a numerical value. How can you use your table to predict the voltage and polarity of a set of ½ cells that you did not even set up i.e. Zinc vs iron? Set the cell up and test your prediction. Can you write some rules for predicting reactions? New Material or new use of existing material Presentation Aim: To make a report on a new material or a new use of an existing material. The report can be written, oral, visual, multimedia or web page. Background: One of the exiting branches of science is always materials research. Some examples of recent materials innovations that are now commonly accepted are - polymers - photovoltaic cells - fibres - lens - ceramics Task : To present a report on one of the materials below or on a innovative material of your choice; carbon nanotubes carbon fibres contact lens materials biodegradable polymers goretex Nano-tex or stain resistant fabrics PSZ Blue-steel coated metal surfaces biscuit trays that degrade competitive swimwear nanoparticles and sunscreen self-cleaning windows The ‘Nano House’ CSIRO project Use of AFM – atomic force microscope Your report needs to be interesting and to be presented at a level that the class can understand. The use of models, sketches and diagrams is encouraged. Written report - about 3 pages. Oral report – about 5 minutes.

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Green chemistry Presentation Aim: To make a report on an aspect of green chemistry. The report can be written, oral, visual, multimedia or web page. Background: The modern issues of water shortages, energy shortages and waste disposal highlight the importance of revisiting how we manufacture and what we manufacture. The principles of green chemistry are designing to provide guidelines for scientists to follow when dealing with chemicals. Task: To present a report on one of the topics below or on a green issue of your choice; super critical carbon dioxide polystyrene blowing agents vinegar – natural vs synthetic green cleaning agents vs commercial products bottled water – costs involved chemical disposal at your school vanilla essence – natural vs imitation artificial flavours vs natural Your report needs to be interesting and to be presented at a level that the class can understand. The use of models, sketches and diagrams is encouraged. Written report - about 3 pages. Oral report – about 5 minutes. Green cleaning agents Experiment Aim: To mix and test a cleaning agent. Task: Green chemistry includes the replacement of synthetic chemicals and toxic chemicals. Many cleaning agents can be replaced with more renewable or safer versions. Essential oils or herbs can be used to improve the odour of your product. Your task is to make and test two alternative cleaning agents. You have to design the test of you cleaning agent versus a commercial agent. Examples: Air freshener – vinegar or baking soda can be used for this. Drain cleaner – vinegar down the drain first, then baking soda. Window cleaner – vinegar. Coin cleaning – Cola can help clean old coins. Tile cleaner – baking soda, liquid soap and water. Add some vinegar just before use. Ant rid – sugar and borax Earwigs – water, garlic, detergent, dried peppers

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Atom Economy – maximise the incorporation of all materials used into the final product (minimise byproduct) % Atom economy = FW of atoms utilized x 100 FW of all reactants used Re-arranging reactions are good i.e. hexane to methylpentane

C

H

H

H C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

HC

H

H

H C

H

C HH

H

C

H

H

C

H

H

C

H

H

H

Addition reactions good – no byproduct ethene + hydrochloric acid chloroethane

C

H

H

C

H

H

+ H Cl C

H

H

H C

H

H

Cl

Substitution less economical because a byproduct will exist

C

H

H

H C

H

H

Cl + H O H C

H

H

H C

H

H

O H + H Cl

Elimination bad because the number of molecules increases.

C

H

H

H C

H

H

H C

H

H

C

H

H

+ H H

synthetic vinegar natural vinegar crude oil fruit juice + culture ( dark + warm) ethane vinegar chloroethane (ethanoic, tartaric, citric acid) ethanol ethanoic acid Vanilla essence similar story

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Green alternatives Banana flavour

crude oil

ethane

C

H

H

H C

H

H

H

pentane

C

H

H

H C

H

H

C

H

H

C

H

H

C

H

H

H

fractional distillation

grow banana tree

blend the banana

synthetic natural

reforming

methylbutane

C

H

H

H C

H

C HH

H

C

H

H

C

H

H

H

chloro,3-methylbutane

Cl C

H

H

C

H

H

C

H

C HH

H

C

H

H

H

3-methylbutan-1-ol

H O C

H

H

C

H

H

C

H

C HH

H

C

H

H

H

chloroethane

C

H

H

H C

H

H

Cl

ethanol

C

H

H

H C

H

H

O H

banana flavouring

C

H

H

H C

H

C HH

H

C

H

H

C

O

O

CH

H

CH

H

H

colour added

substitution

3-methylbutanoic acid

C

H

H

H C

H

C HH

H

C

H

H

C

O

O

H

oxidation

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Exercises to test Yr 11 understanding of basics

Chemical Formulae Aim: To illustrate various aspects of chemical bonding. Background Many students find it very difficult to write correct formulae and equations. The importance of charges and the difference between subscripts and superscripts can be very confusing. Part A: Properties of elements vs elements in compounds You are supplied with a sample of iron filings, sulfur powder and iron sulfide powder. Fill in table 1 Iron filings Sulfur Iron sulfide

Formulae

Description

Magnetic?

Properties

Iron is magnetic. Iron sulfide contains iron. Is iron sulfide magnetic? What conclusion can you make about the properties of an element vs the properties of a compound? If arsenic is poisonous, will arsenic oxide be poisonous? Part B Phases At different times during the year, you will use the symbols like Cu(s), Cu2+(aq), CuCl2 (s), CuSO4 (aq) Each of these can mean a very different thing. Make a poster ( using samples of chemicals ) to illustrate the difference between the copper in the above formulae. How does the electron arrangement differ in Cu(s) from Cu2+(aq) Part C Correct Formulae

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Water has a formula H2O. Hydrogen peroxide, H2O2, has a similar formula to water. Does this change in formula matter? Inspect both liquids. At first glance, the two compounds might seem the same as both are clear liquids. Add a spatula of manganese dioxide to each liquid. What happens? Manganese dioxide causes hydrogen peroxide to decompose rapidly. For this reason it should be stored in a dark and cold cupboard. Hydrogen peroxide also attacks skin vigorously and bleaches fabric. Yes, the slight difference in formula IS very significant. In a similar fashion, iron (II) nitrate, Fe(NO3) 2 is very different from iron (III) nitrate, Fe(NO3) 3. Do they look and behave differently? Chemical Equations Aim: For students to practise writing and balancing chemical equations. Before performing each reaction below, you are asked to - - write the chemical formulae of the reactants - predict what the products will be - predict what you will see taking place. After performing the reaction, you are asked to - - decide if your predicted reaction was correct - explain how your observations match the predicted products - balance your equation. Include the phase of each reactant A: Zinc + Copper Sulfate solution Add a zinc granule to a test-tube ½ filled with the copper sulfate. Leave your test-tube overnight. Were you able to explain the colour change in the solution? Which reagent was in excess? B: Magnesium + Hydrochloric acid solution Add a strip of magnesium to a test-tube ½ filled with 0.5 M hydrochloric acid. How did you test the gas evolved? Which reagent was in excess? C: Silver Nitrate solution + Sodium Chloride solution

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Add a ¼ of a test-tube of sodium chloride solution to ¼ of a test-tube of silver nitrate solution. Can you identify the precipitate? D: ( Teacher demonstration ) Sodium + Water Add a few drops of phenolphthalein indicator to the water before adding a sliver of sodium to the beaker of water. How can the indicator help justify your products? E: Barium Nitrate solution + Copper Sulfate solution. Add a ¼ of a test-tube of barium nitrate solution to ¼ of a test-tube of copper sulfate solution. Can you identify the precipitate? F: Vinegar + Baking Soda Add a spatula of baking soda to a test tube. ½ fill the test tube with vinegar. Vinegar is ethanoic acid, CH 3COOH and baking soda is sodium bicarbonate, NaHCO3 Why are these ingredients in many cakes? G: Calcium carbonate + hydrochloric acid Place a marble chip in a test-tube. ¼ fill the test tube with 2M HCl. Test the gas evolved with a match. H: Lead Nitrate + Potassium Iodide ¼ fill a test tube with 0.1 M lead nitrate solution. Add an equal quantity of 0.1 M potassium iodide solution.

Identify the precipitate formed

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Using WORD on an interactive whiteboard to introduce a topic in an investigative way. Introduction to Acids and Bases Aim: To determine experimentally what an acid is and what a base is. Prior knowledge: You already have some notions about what acids and bases are. Discuss with your bench the following questions 1. What acids or bases can you name? 2. What is an acid and what is a base? Brainstorm your answers onto the whiteboard, incorporating a list of acids and bases that you can name (as shown below). Acids Bases i.e. citric acid oven cleaner Task 1 You are supplied with 5 liquids, labelled 1 to 5. Your task is to identify whether each liquid is an acid or base. You will need to think about how you can do this.

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3 minutes discussion time Possible ideas Try these ideas. Conclusion Did you try these tests 1. Add phenolphthalein to a sample of each. 2. Add magnesium to a sample of each. Results Phenolphthalein Magnesium

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Connection between the two tests. The liquids Sodium hydroxide, hydrochloric acid, ethanol, nitric acid, ammonia. Chemical formula of each of these? NaOH, HCl, CH3CH2OH, HNO3, NH3

Is there a way of predicting from the formula what is an acid and what is a base? Acid Base HCl NaOH HNO3 LiOH H2SO4 NH3 Lowry Bronsted definition.

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..\..\Documents and Settings\All Users\Desktop\SFP Chemistry 1.lnk History http://en.wikipedia.org/wiki/Hydrochloric_acid animations http://web.jjay.cuny.edu/~acarpi/NSC/7-ph.htm Task 2 pH line You are provided with a series of liquids. Measure the pH of each and line them up in order of pH. Use the lowest and highest values to make a scale up to place the items on. Label the strong acids and bases. Label the weak acids and bases.

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1. Boil some grass in a 50:50 mixture of water and metho. Drain the liquid. Sit a strip of filter paper in the liquid. 2. You are provided with two beakers of clear liquid. Boil a sample of each in an evaporating basin. What conclusion can you draw? 3. Heat some flower petals in a 50:50 mixture of metho and water. Drain the liquid. Test the liquid with acid and base. What happens? 4. You have a pottery jar. Use it and other common materials to collect a sample of gas by adding chalk to hydrochloric acid. Did this work? 5. Collect a sample of gas in a gas jar from the addition of magnesium to hydrochloric acid. Sit it beside a gas jar with air in it. How could you test if the gas in one jar is any different from the gas in another? 6. You have a mixture of salt and chalk. How could you separate these and obtain pure samples of each?