chemistry ks4 in an earth context

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Workshop prepared by: Alastair Fleming, Education Department, Keele University Group Leader Alison Garside, Brine Leas School, Nantwich Bernard Besly, ESEU Facilitator Nicola Maddocks, ESEU Facilitator Tonia Robertson-Rogers, ESEU Facilitator Jane Essex, Education Department, Keele University Editor Hazel Benson, Peter Kennett, Chris King, Susannah Lydon, Cally Oldershaw - ESEU Editors

The Earth Science Education Unit CBA1.040, Department of Education, Keele University,

Keele, Staffordshire, ST5 5BG

www . e a r t h s c i e n c e e d u c a t i o n . c o m

The Earth Science Education Unit 3 www.earthscienceeducation.com

Chemistry of me at 16: Teaching KS4 chemistry

Contents

KS4 Starter Spot the Periodic Table through the window 4 KS4 Activity 1 What am I made of? 6 KS4 Activity 2 The metal in me - calcium 10 KS4 Activity 3 The carbon in me 11 KS4 Activity 4 The iron in me 12 KS4 Activity 5 The hot air in me 14 KS4 Activity 6 The value of me what am I worth? 16

Teachers Support Pack

KS4 Plenary activity

Putting it all together 18

Participant Cards

All Activities

Technicians List

All Activities

Summary Start by looking through the window to spot the elements and compounds you can see which form the environment around us. Then consider in Activity 1 what elements we are made of and compare our composition with the lithosphere, atmosphere and hydrosphere. Discover the calcium in our bones in Activity 2 and the carbon we contain in Activity 3. Activity 4 looks at the iron in food that our body needs and Activity 5 investigates the air we breathe. If we added up the value of all the elements in our body, what would we be worth? Find out in Activity 6, before Putting it all together in the plenary activity.

Teachers Support Pack Chemistry of me at 16


Starter Activity: Spot the Periodic Table through the window Introduction: This activity is intended as a warm-up ice-breaker exercise, to stimulate thinking about how pupils might relate the chemistry they are taught to the world outside the window. Key Stage: Chemistry KS4 National Curriculum Ref: Sc3 2g, 3a, 3j Time: 15 minutes Pupil learning outcomes: The things around us, both outside and inside, are made from just a few elements. Context: To consider the idea that chemistry is all around you Common misconceptions: It is often not appreciated how few elements make up the majority of the environment in which we live. Resources: Participant cards Activity: Participants look through a nearby window and attempt to spot the compound or element. This is best done in pairs or groups to encourage discussion. There is a help sheet available.

Follow-up: Pupils can continue to look for examples of common elements and compounds in the local environment on their way home from school.

The view through the window (Starter Activity) Some possible answers to this activity are given below. Many suggestions regarding which compounds participants might spot are given on the Participant Card and are not repeated here. Elements making up these compounds are ticked. Elements (un-combined) are circled.



Spot that compound. Pupils might include the following but, technically, they shouldnt do so, for the reasons given.

Material Constituent(s) Chemical make-up

Steel is iron alloyed with other elements for various purposes. It cannot be seen because either it is covered by a protective coating (paint, plastic) or it has rusted to iron oxides/hydroxides. Also, it is neither an element nor a compound, but a mixture

Common alloys are iron with carbon, chromium, cobalt, niobium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium

Fe plus C, Cr, Co, Nb, Mo, Ni, Ti, W, V, Zr

Air but this cannot be seen since it is transparent. It is also a mixture

N2, O2, Ar, H2O, CO2

Salt if a path has been gritted in the winter, the salt, if visible at all, will not be there for long it will dissolve in the next rain shower, leaving just the grit behind

Salt sodium chloride NaCl

1. What do all these compounds have in

common?

They are all insoluble

They are all solids (unless water is visible)

2. Spot that element. Which elements (un-combined) from the periodic table above can you see? Circle the elements you can spot answers are shown on the periodic table above.

Material Element/symbol Comment

Lead, in flashings (edgings) on roofs Lead Pb Often is dull due to a lead carbonate coating

Copper in pipes or, unusually, as a roof covering

Copper - Cu Pure copper is usually not visible, it is usually coated with a weathering veneer of green copper carbonate compounds

Steel galvanised by zinc in wire fencing, corrugated iron or in the metal steps of telegraph poles

Zinc - Zn This usually has a surface coating of zinc carbonate minerals

Aluminium in ladders or car hubcaps Aluminium - Al This usually has a white surface coating of aluminium oxides

Jewellery on a person of gold, silver or platinum

Gold Au, Silver Ag, Platinum - Pt

Doesnt become coated, so stays bright which is why it is used for jewellery

Diamond in jewellery may be visible Carbon - C

A burnt area will be black with carbon Carbon - C

3. What do all these elements have in

common?

They are relatively un-reactive which is why they were chosen for this purpose

Apart from carbon they are all metals

They are mostly different from those in the first list (Fe, Al, C and Pb are exceptions)

4. Spot the difference. How do your answers differ if you ask which elements and compounds can be spotted in the ordinary room where you are now?

Elements and elements of compounds seen outside but not in

the room Elements and elements of compounds seen in the room but not

outside

There may be slightly fewer elements and elements in compounds in the room, but the answers are likely to be quite similar indicating that we normally interact with rather few elements in our daily lives. However, some items, such as light bulbs, contain an unexpectedly large number of elements.

All photographs can be found in colour on the Earth Science Education Unit website.



Activity 1: What am I made of?

Introduction: Begin thinking about what you are made of as you make the jig-saw and how this compares with the make-up of the lithosphere. Note: The composition of the human body can be shown visually by assembling the elements in the correct proportions as indicated in Appendix 1 to the Technicians List on the final page. Key Stage: Chemistry KS4 National Curriculum Ref: Sc3.3a Time: Assembling the jig-saw should not take more than 5 minutes. With the lead-in and follow-up discussion, probably 20 minutes in all. Pupil learning outcomes: Understand that the human body is made of the same elements that make up the Earth, but in different proportions; understand that the elements are combined together to form different types of compound which form bone, blood, tissue etc; know the main elements in a 15/16 year old. Context: Consolidation of the concepts of elements and compounds, linked to a growing understanding of the patterns of the Periodic Table; the understanding that the properties of compounds are usually very different from the properties of the elements they contain; the understanding of the role of minerals in nutrition. Common misconceptions: It is often poorly appreciated that: the whole of the human body is made of the same stuff (elements and their compounds) as the rest of the physical and biological world; because an element such as sodium is highly reactive does NOT mean that its compounds will also be highly reactive rather the reverse; there is much less iron than people usually think and phosphorous is often overlooked or unknown. Some teenagers may not even appreciate that they are made of elements, and see themselves as being made of different materials from anything else in the world.

Resource list:

Participant Card

Diagram showing the Earths four spheres (lithosphere, atmosphere, hydrosphere, biosphere).

Jig-saw of the elemental composition of the human body copied onto card and cut into pieces

Lead-in: Introduce, or remind the participants of, the names and main features of the Earths four interacting spheres: lithosphere, atmosphere, hydrosphere, and biosphere. Point out (using diagram) that: (1) these spheres are, of course, all made of the

same chemical elements combined and mixed in different ways, but

(2) that the essential differences between each of these are due to their different chemical structures:

lithosphere ionic lattices, atmosphere - small molecules (low inter-molecular forces), hydrosphere - small molecules and ions (relatively high intermolecular forces), biosphere largely polymers.

All the interesting events take place at the interfaces between these spheres! They involve changes in chemical structure, usually meaning chemical reactions, which move the chemical elements between these spheres. So there is a continual cycling of elements through each sphere, a cycling which is essential to the existence of each sphere, especially the atmosphere, hydrosphere and above all the biosphere. Activity: Ask participants to complete the jigsaw. (Note that Si, Al, Ti and Mn are extra elements which look as though they might fit in place of C, N, Cl and Na respectively, but do not. These elements are present in the lithosphere, but not in the body). After participants have completed the jigsaw correctly they complete the third column of the table, followed by the fourth as below.



Element Percentage in the lithosphere*

Percentage in the human body

The human body has more, less or same as the lithosphere

Oxygen 46.6 61 more

Silicon 27.7 none less

Aluminium 8.1 none less

Iron 5.0 0.006 less

Calcium 3.6 1.4 less

Sodium 2.8 0.14 less

Potassium 2.6 0.2 less

Magnesium 2.1 0.03 less

Titanium 0.6 none less

Hydrogen 0.1 10 more

Phosphorus 0.1 1.1 more

Manganese 0.1 none less

Sulfur Less than 0.1 0.2 more

Carbon Less than 0.1 23 more

Chlorine Less than 0.1 0.13 more

Nitrogen Less than 0.1 2.5 more

[* Note 1: The term lithosphere is used here in a general way to mean Earths rocky sphere comparing well with the terms atmosphere, hydrosphere and biosphere. However, figures used in this column, and elsewhere in these worksheets are for the composition of the crust. Figures for the composition of the lithosphere are not used because they are more uncertain and less familiar than those for the crust. * Note 2: The plate tectonic definition of lithosphere (the material that forms the rigid plates) includes the crust (averaging around 15 km in thickness) and the upper part of the mantle the lithosphere averages around 100 km in thickness.] The completed table shows that, while some of the important elements in the human body and the Earths lithosphere are the same, the human body contains some important elements that are rare in the Earths lithosphere and visa versa. Extension activity: Participants consider a table of comparison between the chemical make-up of the human body, the lithosphere, atmosphere and hydrosphere. Some possible answers to the questions they are asked are as follows.

What are the differences and similarities between the chemical composition of your body and its surroundings?

The human body contains more oxygen than the atmosphere and lithosphere, but less than the hydrosphere. It contains much more carbon than all of them and more hydrogen than the

atmosphere and lithosphere, but about the same as the hydrosphere. It contains more nitrogen than the lithosphere and hydrosphere, but much less than the atmosphere. The calcium content of the human body is less than in the lithosphere, but the body contains more than the atmosphere and hydrosphere. The body contains more phosphorus and sulfur than all the others. It contains less potassium than the lithosphere, but more than the atmosphere and hydrosphere. The body contains less sodium than both the lithosphere and hydrosphere but there is none in the atmosphere. The body contains more chlorine than the lithosphere and atmosphere but less than the hydrosphere, it also contains less magnesium and iron than the lithosphere but more than both the hydrosphere and the atmosphere

Is your body most like the atmosphere, most like the lithosphere or most like the hydrosphere?

None of these it is like a combination of all three. Follow-up: Establish that there has to be a continuous flow of each element into and out of the body if this composition is to be maintained a cycling of each element from one or more of the other spheres, either directly or through food. It is useful to mention conservation of matter at some point a constant recycling of elements means, for example, that a carbon atom on the end of your nose could well have been in a dinosaurs big toe.



Jigsaw for Activity 1: What am I made of?



Diagram for Activity 1: What am I made of? The four spheres of the Earth and how they are related



Activity 2: The metal in me calcium Introduction: What makes our bones hard? Try removing the hardness and flame testing the solution that results. Key Stage: Chemistry KS4. National Curriculum Ref: Sc3 2g Time: 20 minutes Pupil learning outcomes: Know how a few elements, including calcium, can be identified in their compounds by use of the flame test. Know that a major role of calcium in the human body is as a component of bones, and that phosphorus and oxygen are also needed for bones. Understand why regular intake of calcium compounds is essential in the diet, and how this fits into the recycling of calcium compounds in nature. Context: The mass of calcium in the body (1 kg in a 70 kg person) is mainly there as one of the elements in bone. This calcium is slowly cycled into and out of the bones, and of course more calcium is needed by children who are still growing. So calcium compounds form an important component of the diet. Common misconceptions: Although pupils are usually aware of the three major organic components of the diet (carbohydrates, proteins and fats), they often fail to understand that minerals are also an important component, and among these calcium compounds make the largest contribution. Resource list:

Participant Card Small thin bones from e.g. rabbit or chicken. Immerse the bones in the acid about one hour before the activity takes place. It would also be sensible to set up a bone in acid some time earlier, eg. the day before.

Hydrochloric acid (1M)

Tweezers

Any calcium salt

Crushed limestone

Bunsen burner and heat proof mat

10 cm lengths of clean thin nichrome wire (NB It is not necessary to mount these in glass rod holders if they are long enough they can be held between the fingers at the far end from the flame, and the other end can be snipped off between tests to ensure a fresh piece of wire for each test). Also the wires are

best cleaned in preparation for each test by dipping in 5M HCl on a watchglass, then flaming them off - but pupils will have to make do with 1M HCl for safety reasons)

Wirecutters/tinsnips

Watch glasses, 5 cm diam Lead-in: We have a lot of calcium inside us - Why? Calcium is a reactive metal so there is likely to be a lot of one or more calcium compounds inside us, but where? Can we find out what they are doing inside the body? Activity: Show a sample of elemental calcium and a sample of a compound containing calcium. Note the different chemical characteristics of the metal as an element and in a compound. [You may wish to show them again the reaction of calcium with water that they may have seen at KS3]. Then ask them to carry out the bendy bones and flame testing activities described on the Participant Card.

Flame testing for calcium (Activity 2) Follow-up: Discuss the flexibility of bone when calcium is removed, such as the issues of calcium deficiency and osteoporosis. Note: brittle bones are caused by protein deficiency. In the context of the big picture, where does the calcium in our bones come from? Here is an example of how the calcium trail might work:

Underlying strata containing calcium compounds are weathered

Calcium is incorporated into the soil profile

It is absorbed through the roots of plants

Grass is eaten by cows

Cows produce milk

Cheese is made from milk

We eat the cheese - and the calcium from it is cycled into our bones



Activity 3 - The carbon in me Introduction: Find out how much carbon is produced when food samples are burnt. Our own bodies would also produce carbon if burnt but it is best to try it with food instead! Key Stage: Chemistry KS4. National Curriculum Ref: Sc3 2q, 3k Time: 15 minutes Pupil learning outcomes: Understand that the carbon in compounds in our bodies comes from the carbon compounds in what we eat, from fats, protein and carbohydrates. Be able to relate the soot formed when foods are burned to the proportion of carbon in the food. Understand the use of the terms organic and inorganic in the context of chemistry. Context: This activity links the percentage of carbon (C) in the human body to the food we eat as the main source of carbon. It can also be used to consolidate the standard word equation for the combustion of carbon compounds. Common misconceptions: It is often not appreciated that what we eat doesnt make a difference to our composition, including the proportion of carbon. We are born with the right composition and keep it to the end! Resource list:

Participant Card

Bench mat

Stand and clamp

Boiling tube

Cold water and measuring cylinder

Tongs (mounting pins can be used instead)

Several different foods to burn. Include potato crisps, which have a high fat content and work well. Other foods could include one high in protein (a meat product), and one high in carbohydrate, although these can be difficult to ignite. Avoid nut-based products in case of allergies.

Safety: Ensure boiling tubes are pointed away from faces. Use eye protection.

Lead-in: Where do the carbon compounds that make up our bodies come from? Are we animal, vegetable or mineral? Both animals and vegetables are organic, minerals are inorganic. Discuss the meaning of organic - we are organic rather than inorganic, we are made up mainly of compounds of carbon, hydrogen, oxygen with a few other elements. If we were to burn, we would produce masses of soot! (mainly because of the fat content of our bodies). Relay the story of spontaneous combustion in humans clothing may act as a wick and the body fat melts and vaporises like a candle. Only the extremities (hands and feet) are left. (see http://www.mysticalblaze.com/SpontaneousCombust.htm or http://www.alternativescience.com/spontaneous-human-combustion-burning-issue.htm).

Apparatus for burning foodstuffs under a boiling tube of cold water (Activity 3) Activity: Carry out the food-burning activity described on the Participant Card. All photographs can be found in colour on the Earth Science Education Unit website.



Activity 4: The iron in me

Introduction: You may be surprised to find that iron metal is added to some foods. Use the magnetic properties of iron to find out how much is in your breakfast cereal. Key Stage: Chemistry KS4 National Curriculum Ref: Sc3 2g Time: 10 minutes Pupil learning outcomes: Know that iron is an essential element in the human body, and therefore in the diet. Understand why iron is needed for haemoglobin in the blood and why some sources of iron in the diet are better than others. Context: Iron is a common element in the Earths crust, so perhaps it is not surprising that it is found in the human body. However there is much more to iron in the body than that, and the role of iron is central to the process of human respiration. For abler pupils, the concepts of oxidation and reduction can be consolidated and widened in this activity. Common misconceptions: Many pupils do not think of rocks as being made of elements and compounds in the same way as the substances they encounter in the chemistry laboratory. Even when simple minerals like quartz (SiO2) are introduced and seen to be simple chemical compounds, the complexity and variability of rock composition seems to lead them to believe that rocks must be made of something else. This activity, as well as others in this sequence, may be used as a vehicle to address this. Resource list:

Participant Card

Any fortified cereal e.g. Special K

Water

Large beaker (1000 ml)

Magnetic stirrer with stirrer bar (preferably a clean white one)

Tweezers Lead-in: What is iron doing in the human body? Iron is a common element in the Earths crust, so perhaps it is not surprising that it is found in the body, but what is its role - what does it do?

Refer to the dietary information for example on a packet of Kelloggs Special K and ask whether they would expect the iron to be present as the element or as a compound of iron. How could iron as an element be extracted from Special K? Try the activity below. Activity: As the mixture of crushed cereal in water is stirred with the magnetic stirrer, fine iron power adheres as a grey coating to the magnetic stirrer bar to the surprise of most. Since it is unlikely that a school laboratory will have several magnetic stirrers, this can be done as a teacher demonstration with pupil participation, or as one activity in a circus.

Apparatus for finding the iron in cereals (Activity 4) Follow up: This activity shows how the iron content in the cereal is increased by the addition of fine iron powder. At this point the story of the KS3 SAT question set a few years ago could be told, when this experiment was described and questions asked about what was happening. The magazine New Scientist heard about the question, failed to check what was behind it, and jeered at what it regarded as a nonsense suggestion, that Special K contained iron filings. If they had checked their facts, they would have found that the science was correct, that it had been checked out with Kelloggs, and above all that it is iron powder, not iron filings, that is used an important difference. Although several scientists, including teachers, wrote in to correct the magazine, there seems to have been no official correction published.



Why are iron compounds not used? The body requires Fe2+ for haemoglobin and iron tablets contain iron(II) sulphate and are swallowed whole. But if this compound were to be used as a fine powder in the cereal it would dissolve and oxidise to Fe3+ before reaching the stomach. If the iron content of the body is to be increased, the iron must be digested as Fe2+. When the iron powder reaches the stomach, it reacts with the hydrochloric acid in the stomach to form iron(II) chloride (and hydrogen), so providing Fe2+ just where it is needed! Importantly, iron eaten in powder form has no taste. This story will need to be adapted to the level of the pupils in the class, but it forms a useful example of the application of understanding of simple chemistry to their lives. This can then lead into a wider discussion on the benefits and possible hazards of vitamin and mineral supplements.

Extension: Compare and contrast the amount of iron extracted from other cereals and discuss the differences. Special K packets quote 20 mg of iron per 100g of cereal, while cornflakes, which are fortified at a lower level, have about 7 mg of iron per 100g while un-fortified cereals have 1 2 mg iron per 100g. Also try comparing and contrasting the compositional analyses of contents given on different cereal packets. Acknowledgement: This activity is taken from: Lister, T. (1996) Classic chemistry demonstrations. London: Royal Society of Chemistry, 5 6. All photographs can be found in colour on the Earth Science Education Unit website.



Activity 5: The hot air in me

Introduction: How might the atmosphere of the early Earth have originated and how might it have changed to contain the gases that are vital to our lives? Investigate how much of the air we breathe is actually composed of oxygen. Key Stage: Chemistry KS4. National Curriculum Ref: Sc3.2 l, m, p Time: 10 minutes Pupil learning outcomes: Know that the most abundant element in the body is oxygen, most of which combined with hydrogen as water. Know that water intake comes both from drinking liquids and from eating such things as fruit and vegetables. Know the approximate percentages of the most important gases in air nitrogen, oxygen and carbon dioxide. Understand how percentages of the reactive and unreactive components in air can be found by using another element to remove the reactive component. Context: Human life depends on respiration, for which we need to draw on resources from all the Earths spheres (lithosphere, hydrosphere, atmosphere and biosphere), but in particular, the gases of the atmosphere. Common misconceptions: Many pupils think air is made mainly or even completely of oxygen, and they do not abandon this misconception even when they have learnt the values for the composition of air by heart!

Resource list:

Participant Cards

2 gas syringes, 100 ml, with plungers loosely fastened with string, to prevent them dropping out of the syringes onto the bench and smashing

freshly reduced wire-form copper (or if this is unavailable, copper turnings) see Technicians list

Silica (glass) combustion tube, 15 cm long

2 short pieces of silica glass rod that fit loosely into the tube

3 way tap to allow initial adjustment of plunger positions

Rubber tubing short lengths to connect

Cartoon poster or OHT prepared to show a volcano with past atmospheric composition, and then arrows and clouds linking to present day atmospheric composition

Lead-in: Can we live without air? Discuss the importance of air. The average person breathes in about 14,500 litres of air each day when resting. For someone doing energetic exercise, the air intake could be about 30 40 litres of air every minute. All in all, we need a lot of air! But where did the air we breathe come from and what is it made of?



Activity 5A: Name that gas The completed table should be as follows:

Gas description Gas(es) Cloud letter

These three constituents of volcanic gas either form the water of the oceans or dissolve in the ocean waters.

Water vapour

Carbon dioxide

Sulfur oxides

c

These two constituents of volcanic gas are not very reactive and so remain in the atmosphere and their percentages have built up over geological time

Nitrogen

Argon

b

This gas is found in varying amounts in the atmosphere, depending on the temperature and the balance between such processes as evaporation and condensation

Water vapour f

During photosynthesis by plants, this gas is released. The process has added an important gas to the atmosphere that is not found in volcanic gas

Oxygen e

This constituent of volcanic gas not only dissolves in the oceans but is also used by plants during photosynthesis

Carbon dioxide d

This constituent of volcanic gas has very low density and so is easily lost from the atmosphere to outer space. It is a gas that has low atomic mass and so is found early in the periodic table

Hydrogen a

Acknowledgement: This activity is taken from: King, C. & York, P. (1995) SoE1 Changes to the Atmosphere, Sheffield: ESTA, Figure A9.3. Activity 5B: How much air is used when copper reacts with air? This is a teacher demonstration described on the Participant Card (but not intended for pupils to do themselves). The Participant Card contains questions for those observing the demonstration.

The apparatus for reacting copper with air (Activity 5)

Answers to questions on Participant Card:

What volume of air was set at the start? 100 cm3

What volume of gas was still there after passing it over hot copper? 79 cm3

So what volume of gas was used up in reaction with the copper? 21 cm3

And what percentage is this of the whole air? - 21%

What is the name of the gas that reacted with the copper? - oxygen

What is the name of the main gas in air that did not react? - nitrogen

Follow up: Discuss results and develop a word equation for the reaction that takes place. Explain that the copper reacts with something in the air to give the grey-black product that the pupils observe. This is a compound. The gas that remains is unreactive. The reaction can be written as: Copper + Air Product + Inactive air (79%) The 21% active gas in the air is oxygen. Of the remaining 79%, 78% is nitrogen The grey-black solid is copper (II) oxide. Extension: Ask whether the pupils would expect any change in the mass of the copper during the experiment and why? (The mass of the copper increases as it becomes copper oxide). Acknowledgement: This activity is taken from: Hunt, J.A & Sykes, A. (1984) Chemistry. York: Longman.

All photographs can be found in colour on the Earth Science Education Unit website.



Activity 6: The value of me

Introduction: How much are you worth? Use the prices to find out how much the materials that make up your body would cost if you were to buy them separately. Then discuss what you are really worth to your family, friends and as a citizen of your country. Key Stage: Chemistry KS4. National Curriculum Ref: 3.2.g and 3.3k Time: 20 minutes Pupil learning outcomes: Be able to calculate the monetary value of a stated quantity of an element, given the market value of that element. Know that Britain is made of rocks that contain all these elements, and that in a few places the rocks may contain enough of an element to be an economic source for its extraction. Understand that we depend upon the rocks of the Earths crust to supply our needs for many elements, both for the biosphere and to provide our modern way of life. Understand in particular that the mineral components of our diet come from the rocks, mainly via the soil to the plants and then the animals that together form our diet. Understand that our market value as a collection of elements forming our bodies has no real meaning in terms of our value as human beings! Context: All living things depend upon minerals derived from the lithosphere, and most of the raw material we need for everything we use in our day-to-day lives also derive from the lithosphere. This is all bound up with the way elements are cycled in and out of the lithosphere, both by natural processes and by the processes of the mineral industry and waste disposal.

Common misconceptions: Some people think that drinking water supplies minerals for our diet. While several trace elements may be supplied this way, it is not a significant route for the major minerals, which are supplied mainly in our food, and also perhaps by mineral supplements. Resource list:

Participant Cards

Geological map of the UK Lead-in: Where do we get the minerals in our diet from? By discussion establish that ultimately they must come from the lithosphere (or the Earths crust). Since we live in Britain, this idea can be linked to geological maps of the UK, and if possible to the range of mineral extraction for different elements that occurs, or has occurred in the past, in different parts of Britain. This leads to the question of the economic cost of these elements, and wondering what we ourselves might be worth as a collection of elements. Activity: The Participant Cards provide a data table giving the market prices for 12 important elements in their bodies (taken from the 1997 Aldrich Catalogue), along with the mass of each element in a typical 70kg body and the percentage of body mass this represents. Participants calculate the value of these elements EITHER in the typical 70 kg body OR in their own body if they know their own mass. They then calculate the total value of the body. This process can be speeded up by asking each member to carry out the calculation for one element and combining all the results together at the end.

Results for a 70 kg human body are as follows:

Element % of body mass from each element

Mass of element in a 70kg person

Price per kg Value of element in 70 kg person

Oxygen 61 42.7kg 3.43 146.46

Carbon 23 16.1kg 16.90 272.09

Hydrogen 10 7.0kg 167.67 1173.69

Nitrogen 2.5 1.8kg 1.60 2.88

Calcium 1.4 1.0kg 144.00 144.00

Phosphorous 1.1 770g 21.00 16.17

Potassium 0.2 140g 790.00 110.60

Sulfur 0.2 140g 9.40 1.32

Sodium 0.14 98g 82.40 8.07

Chlorine 0.13 95g 198.23 18.83

Magnesium 0.03 21g 34.90 0.73

Iron 0.006 4.2g 49.50 0.21

Total value 1877.80



Follow-up: Discuss of the validity of the elemental value calculated, both in economic terms and also in terms of ethics! Consider biological mechanisms for maintaining steady levels of the elements in the body (homeostasis and excretion).

Extension: Consider the role of the water cycle and hence the presence of dissolved minerals in water supplies. Relate this in particular to borehole abstraction, where rainwater has infiltrated the soil and percolated through the underlying rock, reacting with it and dissolving substances. Develop the understanding that groundwater is stored in aquifers, which consist of porous, permeable rocks (not large caverns underground!) while surface water is stored in reservoirs.



Plenary Activity: Putting it all together Introduction: The elements in your body have been cycled through many places before they formed you. Where else are they found? Key Stage: Chemistry KS4 National Curriculum Ref: Sc3 2 l, p, q Time: 15 minutes (approx) Pupil Learning Outcomes: Revise the lessons learned in the earlier part of the workshop, and acquire a broader perspective of the relationship between their own bodies and the world around them.

Context: Re-visit some of the key elements explored in earlier activities and see where they are found in the wider environment. Common misconceptions: Pupils may not realise that most of the common elements form compounds important in all of Earths spheres. Resource List:

Participant Cards Lead-in: Where (chemically) do you come from? Where else on Earth are the elements that make up your body found? Activity: Groups complete the tables on the Participant Cards. Answers are as shown below.

Element Natural example of element or its compounds Sphere where it

is found

Calcium Calcium carbonate in limestone and marble

Calcium dissolved in hard water

Calcium carbonate in teeth and bones

Calcium carbonate in shells

Another example? Calcium dissolved in the sea

L

H

B

B if living,

L if dead

H

Chlorine Sodium chloride (salt) in sea water

Sodium chloride in rocks

Chloride ions in plants

Chloride ions in animals

Another example? Chloride ions in the soil

H

L

B

B

L

Nitrogen Nitrogen in air

Nitrate in soil water

Nitrogen in bacteria in soil

Nitrogen in protein in plants

Nitrogen in protein in animals

Nitrogen in urea

Another example? Nitrogen in excretion

A

H

B

B

B

B if in animal

L if in soil

H if in sewage

B

Sodium Sodium chloride (salt) in sea water


Sodium ions in plants

Sodium ions in animals

Another example? Sodium ions in soil water

H

L

B

B

H

Carbon Carbonate such as limestone and marble

Carbon in fossil fuel coal

Carbon in fossil fuel oil and natural gas

Graphite formed of carbon

Diamond formed of carbon

Carbon dioxide dissolved in seas

Carbon dioxide in the air

Carbon dioxide used in photosynthesis

Carbon dioxide produced by respiration

Carbon in carbohydrates in plants

Carbon in carbohydrates in animals

Another example? Carbon monoxide in the air

L

L

L

L

L

H

A

B

B

B

B

A



Oxygen Oxygen dissolved in water

Oxygen in the air


Carbon dioxide dissolved in water

Oxygen reacted with metals (eg. rust)

Oxygen used in breathing

Oxygen produced by photosynthesis

Another example? Oxygen in iron ore (magnetite)

H

A

A

H

L

B

B

L

Iron Iron in haemoglobin in red blood cells

Iron oxide in ore (hematite)

Iron sulfide in rocks (fools gold)

Iron metal crystals in igneous rock (e.g. basalt, granite)

Dissolved iron compounds in rivers

Iron in food (e.g. green vegetables, meat, fortified cereal)

Iron compounds in faeces

Another example? Iron stained weathered rock surfaces

B

L

L

L

H

B

B

L

Follow-up: When groups are clear where in the Earths spheres these examples are found follow up with a discussion of how they are cycled from one sphere to the others. Each group can take an element and show how it can be moved to another sphere, as shown below:

Element Natural example of element or its

compounds Sphere

where it is found

Sphere it can be cycled to

Process





Another example? Calcium dissolved in the sea

L H B B H

H L H L B

Dissolved by acid rain

Deposited in stalactites

Dissolved by water after burial

Buried to form limestone

Used to form sea shells

Lithosphere (Plenary Activity)

Atmosphere (Plenary Activity)

Biosphere (Plenary Activity)

Hydrosphere (Plenary Activity)

Participant Cards Chemistry of me at 16

Spot the Periodic Table through the window

1. Spot that compound: Look out of

the window you can see many

different compounds made of

different elements. Tick the

elements which make up the

compounds you can spot. A help

sheet is available if you need help.

2. What do all these compounds have

in common?

3. Spot that element: Which

elements (uncombined) from the

periodic table above can you see?

Circle the elements you can spot.

4. What do all these elements have in

common?

5. Spot the difference: How do your

answers differ if you ask which

elements and compounds can be

spotted in the ordinary room where

you are now?

Elements and elements of compounds

seen outside but not in the room

Elements and elements of compounds

seen in the room but not outside


Spot the Periodic Table through the window help sheet

The chemistry of common outdoor compounds

Material Constituent(s) Chemical make-up

Kaolinite contains: Al, Si, O, H

Montmorillonite contains: Na Ca, Al, Mg, Si, Al, O,

H

Bricks/tiles these are

made from clays which are

baked in a kiln to form

bricks/tiles. Clays contain

clay minerals and the most

common ones are:

Illite contains: K, Al, Si, O, H

Tricalcium silicate contains: Ca, O, Si

Dicalcium silicate contains: Ca, O, Si

Tricalcium aluminate contains: Ca, O, Al

Tetracalcium aluminoferrite

contains:

Ca, O, Al, Fe

Cement cement is usually

mixed with sand in mortar or

with sand and rock chips in

concrete. Major cement

constituents include:

Calcium sulfate (gypsum) CaSO4

Bitumen (asphalt or tar) Long chains of hydrocarbon

molecules including:

H, C, N, S, O

Rock made of minerals

(roofing slate is a rock)

The most common minerals are

made of the most common

elements in the Earth crust:

O, Si, Al, Fe, Ca, Na, K,

Mg, Ti

Silicon dioxide (silica sand,

quartz)

SiO2

Sodium carbonate Na2CO3

Calcium carbonate CaCO3

Glass the main constituents

of float glass the most

common form of glass today,

are:

Magnesium carbonate MgCO3

Plastic polymers Plastic polymer chains are made

mainly of:

C, H, O, Si

Resin compounds mainly of: C, O, H

Primary pigment commonly

titanium dioxide

TiO2

Paint include a form of glue

(resin), a primary pigment,

secondary pigments and

colorants and a solvent. In

dry paint, the solvent

evaporated when the paint

dried

Simple secondary pigments

include:

iron oxide, used to give yellows,

reds and browns

chromium oxide giving green

lead oxide giving red

Fe2O3

Cr2O3,

Pb3O4

Human body 99% of the mass of the human

body is made of just six

elements:

O, C, H, N, Ca, P

Plants Plants are formed mainly of the

following elements, with trace

amounts of around ten others:

O, C, H, N, P, S, Si


Activity 1: What am I made of?

Introduction:

Begin thinking about what you are made

of as you make the jig-saw and how

this compares with the make-up of the

lithosphere.

Activity:

Put the jig-saw together correctly

Write the information from the jig-

saw into the table below to compare

the percentage of elements in your

body with the percentage of

elements in the Earths lithosphere

Element Percentage in the

lithosphere

Percentage in the

human body

The human body

has more, less

or same as the

lithosphere

Oxygen 46.6

Silicon 27.7

Aluminium 8.1

Iron 5.0

Calcium 3.6

Sodium 2.8

Potassium 2.6

Magnesium 2.1

Titanium 0.6

Hydrogen 0.1

Phosphorus 0.1

Manganese 0.1

Sulfur Less than 0.1

Carbon Less than 0.1

Chlorine Less than 0.1

Nitrogen Less than 0.1

Then complete the final column of

the table by writing more if the

human body has a greater

percentage of the element than the

lithosphere, less of it is lower or

same if it is about the same.

How similar is the composition of

the human body to that of the

Earths lithosphere?


Activity 1: What am I made of? Extension activity

Look at the table below giving the

average composition of the three parts

of our environment; the lithosphere

(solid rock of the Earths outer layers),

the hydrosphere (rivers, lakes, seas)

and atmosphere (the air) as well as the

composition of the human body.

Average % in the following locations Element

Atmosphere Lithosphere Hydrosphere Human body

Oxygen 21 46.6 86 61

Carbon 0.008 Less than 0.1 A trace * 23

Hydrogen Varies * 0.1 10.8 10

Nitrogen 78.03 Less than 0.1 A trace # 2.5

Calcium 0 3.6 0.04 1.4

Phosphorous 0 0.1 A trace + 1.1

Potassium 0 2.6 0.04 0.2

Sulfur 0# Less than 0.1 0.08 0.2

Sodium 0 2.8 1.07 0.14

Chlorine 0 Less than 0.1% 1.92 0.13

Magnesium 0 2.1 0.13 0.03

Iron 0 5.0 0 0.006

Aluminium 0 8.1 0 0

Silicon 0 27.7 0 0

Titanium 0 0.6 0 0

Manganese 0 0.1 0 0

* depending on

whether air is

damp or dry

*as carbonate

ions

# as nitrate

ions

# unless sulfur

dioxide present

due to burning

fossil fuels

+ as phosphate

ions

What are the differences and

similarities between the chemical

composition of your body and its

surroundings?

Is your body most like the

atmosphere, most like the

lithosphere or most like the

hydrosphere?


Activity 2: The metal in me calcium

Introduction:

What makes our bones hard? Try

removing the hardness and flame

testing the solution that results.

We cant use our bones for this test, so

we are using animal bones instead

because they have the same

composition as ours.

Use eye protection.

Activity 2A: Removing the hardness

You have been given a small bone

that has been covered in 1M

hydrochloric acid and left for an

hour or so.

Remove the bone from the solution

with tweezers, rinse it off and dry

it. Then compare it with an

untreated bone.

Pass the treated and untreated

bones around the group.

Activity 2B: Flame testing

Conduct flame tests on the known

calcium salt provided and on crushed

limestone, as follows:

Dip the flame test wire in

hydrochloric acid on the watch

glass.

Holding the wire firmly at the

far end, touch the tip of the

wire into the bottom corner of a

strong blue Bunsen flame, and

hold it there until any colour

from the wire in the flame dies

away.

Repeat this until the wire gives

no colour to the flame the wire

is now clean.

Now dip the wire into acid, and

then into a sample of a known

calcium compound. What colour

does it give to the flame now?

Clean the wire again as before,

and when clean repeat the test

using a sample of powdered

limestone. Is the colour given to

the flame the same?

Now use this flame testing method

to discover if there is calcium in

bones. Dip the wire into the solution

from activity 2a and carry out the

flame test. Does this give a calcium

colour?

Where might the calcium in our

bones have come from?

Flame testing for calcium


Activity 3: The carbon in me

Introduction

Find out how much carbon is produced

when food samples are burnt. Our own

bodies would also produce carbon if

burnt but it is best to try it with

food instead!

Use eye protection, and ensure that

boiling tubes are pointing away from

faces.

Apparatus for burning foodstuffs

under a boiling tube of cold water

Activity Hold a potato crisp (with a high fat

content) with tongs. Light it in a

Bunsen flame and place the burning

crisp under a boiling tube half-full

of water.

Watch for condensation forming on

the tube and dripping onto the food

sample it might put out the flame.

Wait until the food has burnt out.

How much soot has been deposited

onto the test tube?

Burn different food types e.g. one

high in protein, and one high in

carbohydrate. Do they all give the

same results?


Activity 4: The iron in me

Introduction

You may be surprised to find that iron

metal is added to some foods. Use the

magnetic properties of iron to find out

how much is in your breakfast cereal.

Apparatus for finding the iron in

cereals

Activity: Iron grains in cereal can

you be serious?

Measure about 50g (or around one

serving) of cereal into the beaker.

Crush the cereal by hand, or in a

pestle and mortar.

Add about 500 ml water.

Use a magnetic stirrer to stir the

mixture for a few minutes.

Remove the stirrer bar using

tweezers and look at it closely.

What do you see?



Introduction

How might the atmosphere of the early

Earth have originated and how might it

have changed to contain the gases that

are vital to our lives? Investigate how

much of the air we breathe is actually

composed of oxygen.

Activity 5a: Name that gas

Look at the cartoon provided.

It shows the composition of volcanic

gas that comes from volcanoes

today, which we think is similar to

the early atmosphere, several billion

years ago.

Between these are arrows and

clouds (a f) which link them.

Study the information table below,

which describes the gases.

Now work out which cloud

represents which gases, and write

the answers into the table.

Gas description Gas(es) Cloud

letter These three constituents of volcanic gas either form

the water of the oceans or dissolve in the ocean waters.

These two constituents of volcanic gas are not very

reactive and so remain in the atmosphere and their

percentages have built up over geological time.

This gas is found in varying amounts in the atmosphere,

depending on the temperature and the balance between

such processes as evaporation and condensation.

During photosynthesis by plants, this gas is released.

This process has added an important gas to the

atmosphere that is not found in volcanic gas.

This constituent of volcanic gas not only dissolves in the

oceans but is also used by plants during photosynthesis.

This constituent of volcanic gas has very low density and

so is easily lost from the atmosphere to outer space. It

is a gas that has a low atomic mass and so is found early

in the Periodic Table.



Activity 5B is a teacher demonstration

(described here for teachers only)

Answer these questions before, during

and after the demonstration.

Activity 5B: How much air is used

when copper reacts with air?

What volume of air was set at the

start?

What volume of gas was still there

after passing it over hot copper?

So what volume of gas was used up

in reaction with the copper?

And what percentage is this of the

whole air?

What is the name of the gas that

reacted with the copper?

What is the name of the main gas in

air that did not react?

The apparatus for reacting copper with

air

The Activity

Set-up the apparatus well in

advance, as shown in the diagram

(add string to each plunger, to stop plungers popping out, and a tap in the middle)

Pack freshly-reduced wire-form

copper (or copper turnings) into the

silica tube, using a short piece of

silica glass rod at each end to

prevent the wire pieces spilling out

Set the apparatus with one syringe

containing 100 cm3 of air and the

other set to the zero mark, using

the tap to vent unwanted air

Heat the copper strongly with the

Bunsen burner

As the copper is heated, use the

syringes to push air to and fro

across it

As the copper is heated in air it

becomes grey-black

As the copper is heated the volume

of air decreases

When no more reduction in gas

volume occurs turn off the Bunsen

burner

Leave the apparatus to cool

Measure the volume of air remaining

This will allow the observers to

answer the questions on the

Participant Card as above


Activity 6: The value of me

Introduction

How much are you worth? Use the

prices to find out how much the

materials that make up your body would

cost if you were to buy them

separately. Then discuss what you are

really worth to your family, friends

and as a citizen of your country.

Activity

You are provided with a data table

giving market prices for twelve

important elements in your body.

The table also shows the mass of each

element in a typical 70kg adult human

body, and the percentage of body mass

this represents.

For each element, calculate:

EITHER: the value of the typical 70 kg

human body as follows:

First find the mass in kilograms

of each element in the body

From the table, find the value of

1 kg of that element

Now multiply the mass of the

element by the value of 1 kg of

that element

OR: the value of your own body if you

know your own mass in kilograms and

can use the percentage composition

column. Use the same stages as those

above.

Finally, calculate the total value of the

main elements in the body.


Data table for a 70 kg person

Element % of body mass

from each

element

Mass of

element in a

70kg person

Price per kg Value of

element in 70

kg person

Oxygen 61 42.7kg 3.43

Carbon 23 16.1kg 16.90

Hydrogen 10 7.0kg 167.67

Nitrogen 2.5 1.8kg 1.60

Calcium 1.4 1.0kg 144.00

Phosphorous 1.1 770g 21.00

Potassium 0.2 140g 790.00

Sulfur 0.2 140g 9.40

Sodium 0.14 98g 82.40

Chlorine 0.13 95g 198.23

Magnesium 0.03 21g 34.90

Iron 0.006 4.2g 49.50

Total value

Data table for your own body mass of X kg

Element % of body

mass from

each element

Calculation

of mass of

element in

me, in kg

Mass of

element in

me, in kg

Price per kg Value of

element in

me

Oxygen 61 61/100 x X 3.43

Carbon 23 23/100 x X 16.90

Hydrogen 10 10/100 x X 167.67

Nitrogen 2.5 2.5/100 x X 1.60

Calcium 1.4 1.4/100 x X 144.00

Phosphorous 1.1 1.1/100 x X 21.00

Potassium 0.2 0.2/100 x X 790.00

Sulfur 0.2 0.2/100 x X 9.40

Sodium 0.14 0.14/100 x X 82.40

Chlorine 0.13 0.13/100 x X 198.23

Magnesium 0.03 0.03/100 x X 34.90

Iron 0.006 0.006/100 x

X

49.50

Total value


KS4 Plenary Activity: Putting it all together

Introduction

The elements in your body have been

cycled through many places before

they formed you. Where else are they

found?

Activity

Show in which sphere each of the

examples over the page is found by

writing the initial letter of the sphere

opposite each example. The first has

been done for you to help you (L =

lithosphere; H = Hydrosphere; A =

Atmosphere; B = Biosphere)

Then add an example of your own and

show where it is found.

Lithosphere

Atmosphere

Biosphere

Hydrosphere


Element Example of element or its compounds Sphere where it is

found





Another example? -

L

Chlorine Sodium chloride (salt) in sea water


Chloride ions in plants

Chloride ions in animals

Another example? -

Nitrogen Nitrogen in air

Nitrate in soil water

Nitrogen in bacteria in soil

Nitrogen in protein in plants

Nitrogen in protein in animals

Nitrogen in urea

Another example? -

Sodium Sodium chloride (salt) in sea water


Sodium ions in plants

Sodium ions in animals

Another example? -

Carbon Carbonate such as limestone and marble

Carbon in fossil fuel coal

Carbon in fossil fuel oil and natural gas

Graphite formed of carbon

Diamond formed of carbon

Carbon dioxide dissolved in seas


Carbon dioxide used in photosynthesis

Carbon dioxide produced by respiration

Carbon in carbohydrates in plants

Carbon in carbohydrates in animals

Another example? -

Oxygen Oxygen dissolved in water

Oxygen in the air


Carbon dioxide dissolved in water

Oxygen reacted with metals (eg. rust)

Oxygen used in breathing

Oxygen produced by photosynthesis

Another example? -


Iron Iron in haemoglobin in red blood cells

Iron oxide in ore (hematite)

Iron sulfide in rocks (fools gold)

Iron oxide crystals in igneous rock (e.g. basalt,

granite)

Dissolved iron compounds in rivers

Iron in food (e.g. green vegetables, meat, fortified

cereal)

Iron compounds in faeces

Another example? -

Then draw a table like the one below and complete it for one of the elements

above. An example shows you how to do this.

Element Natural example of element or

its compounds

Sphere

where it is

found

Sphere it

can be

cycled to

Process

Calcium Calcium carbonate in

limestone and marble

L

H

Dissolved by acid rain

Technicians List Chemistry of me at 16

Technicians List

KS4 Starter activity - Spot the Periodic Table through the window Participant Cards A room with a reasonable view from the

window

KS4 Activity 1 - What am I made of? Participant Card PowerPoint or OHT slides showing the

Earths four spheres (lithosphere, atmosphere, hydrosphere, biosphere).

Jig-saw of the elemental composition of the human body, copied onto card and cut into pieces

KS4 Activity 2 - The metal in me calcium Participant Card Small thin bones from e.g. rabbit or chicken. Hydrochloric acid (1M).Immerse the bones in

the acid about one hour before the activity takes place. It would also be sensible to set up a bone in acid some time earlier, eg. the day before.

Tweezers Any calcium salt Crushed limestone Bunsen burner and a heat proof mat 10 cm lengths of clean thin nichrome wire

(NB It is not necessary to mount these in glass rod holders if they are long enough they can be held between the fingers at the far end from the flame, and the other end can be snipped off between tests to ensure a fresh piece of wire for each test. Also the wires are best cleaned in preparation for each test by dipping in 5M HCl on a watchglass, then flaming them off - but pupils will have to make do with 1M HCl for safety reasons)

Wirecutters/tinsnips Watch glasses, 5 cm diam

KS4 Activity 3 - The carbon in me Participant Card Bench mat Stand and clamp Boiling tube Cold water and measuring cylinder Tongs (mounting pins can be used instead) Several different foods to burn. Include

potato crisps, which have a high fat content and work well. Other foods could include one high in protein (a meat product), and one high in carbohydrate, although these can be difficult to ignite. Avoid nut-based products in case of allergies.

KS4 Activity 4 - The iron in me Participant Card Any fortified cereal, e.g. Special K Water Large beaker (1000 ml) Magnetic stirrer with stirrer bar (preferably a

clean white one) Tweezers

KS4 Activity 5 - The hot air in me Participant Cards 2 gas syringes, 100 ml, with plungers loosely

fastened with string, to prevent them dropping out of the syringes onto the bench and smashing

freshly reduced wire-form copper (see photograph below) (or if freshly reduced wire-form copper is unavailable, copper turnings)

Silica (glass) combustion tube, 15 cm long 2 short pieces of silica glass rod that fit

loosely into the tube 3 way tap to allow initial adjustment of plunger

positions Rubber tubing short lengths to connect Cartoon poster or OHT prepared to show a

volcano with past atmospheric composition, and then arrows and clouds linking to present day atmospheric composition

The preparation of freshly reduced copper wire, using the lab gas supply

Technicians List Chemistry of me at 16

KS4 Activity 6 - The value of me what am I worth? Participant Cards Geological map of the UK

KS4 Plenary activity - Putting it all together Participant Cards

----------------------------------------------------------

Appendix 1. Optional - A visual representation of the human body The elemental composition of the human body can be illustrated visually as follows: Prepare sealed and labelled samples of some

common elements in the human body. Where possible each sample should have the same mass as contained in an average 70kg human body, but where not possible a smaller sample taped to e.g. a box having a similar volume to that which that mass of element would occupy. See the Data Sheet on the Participant Card for a table of the correct quantities. Oxygen: a standard medical oxygen

cylinder, or the small size of oxygen cylinder found in some schools (less than 1 metre long), when full probably contains somewhat less than the 43 kg of oxygen, but is the nearest approximation to this mass of oxygen in the body. If such a cylinder is available, it should be displayed securely and clearly labelled: Oxygen: 43 kg (gas under high pressure). Failing this, a large box of approx. 50 litres capacity (40cm X 40cm X 30cm), wrapped in coloured paper and labelled Oxygen: 43kg (volume as occupied by liquid oxygen).

Carbon: 16kg of coke, charcoal or a high carbon fuel such as phurnacite, displayed if possible in a transparent box labelled: Carbon: 16kg.

Hydrogen: the small size of laboratory cylinder probably contains somewhat more than the 7kg of hydrogen found in the human body, but as with oxygen this would be the nearest approximation. Displayed securely and labelled: Hydrogen 7kg (gas under high pressure). Failing this a box about twice the size as suggested for oxygen above, wrapped in coloured paper and labelled: Hydrogen: 7kg (volume as occupied by liquid hydrogen)

Nitrogen: a small nitrogen cylinder would need to be nearly empty to contain a mass of nitrogen approximating to the 1.8kg in the body! Such a cylinder could be displayed with a label stating: Nitrogen 1.8kg (cylinder almost empty), or use a box about 2 litre capacity (20cm X 10cm X 10cm) wrapped in coloured paper and

labelled: Nitrogen: 1.8kg (volume as occupied by liquid nitrogen)

Calcium: a mass of 1kg is probably too much for the average school chemical store to provide, but if it can be done, so much the better! displayed with due regard to safety in a clear container and labelled: Calcium: 1kg. Failing this, a smaller sample displayed in the same way, attached to a box or block of volume 650 cm3 (e.g. 10 X 10 X 6.5 cm) painted silver or covered with cooking foil.

Phosphorus: 770g of red phosphorus is probably more than is normally kept in stock by schools, so a smaller sample in a sample bottle attached to a block/box of volume about 333cm3 (e.g. 7 X 7 X 7cm), labelled: Phosphorus: 770g

Potassium: it is unlikely that most schools will have 140g of potassium, so prepare a box/block of volume 120 cm3 (5 X 5 X 5cm) covered in foil paired with a small sample bottle containing potassium under oil. Label: Potassium: 140g

Sulfur: 140g of flowers of sulfur or roll sulfur in a bottle labelled: Sulfur: 140g (a school chemical store should have little problem supplying this!)

Sodium: a sample of 98g of sodium (displayed under oil) may be possible in some schools, but otherwise a box/block of volume 100cm3 (5 X 5 X 4cm) covered in foil paired with a small sample bottle containing sodium under oil. Label: Sodium: 98g

Chlorine: it is highly unlikely that most schools will have small bench cylinders of chlorine used for demonstrations (but if a school does, then a nearly empty cylinder would be appropriate). A box/block of volume 32 litres would approximate to 95g of chlorine gas, but for comparability to the other gases, a box of approx. volume 60cm3 (e.g. 4 X 4 X 4cm) could represent 95g of liquid chlorine. Label: Chlorine: 95g (volume as occupied by liquid chlorine)

Magnesium: 21g. A partly used reel of magnesium ribbon may suffice, or a sample bottle with 21g of magnesium powder. Label: Magnesium: 21g

Iron: 4.2 g. If possible a single nail of appropriate size will make the point quite forcefully! Otherwise iron filings in a sample bottle could be used. Either way, label: Iron: 4.2g

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