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Avogadro's HypothesisThe Italian, Amadeo Avogadro (1776-1856) was trained inLaw, but became very interested in Science.

In 1811, he noticed the similarity between Gay-Lussac'sLaw (an empirical "law" based on experiment) and theconcept that atoms must combine in simple, whole numberratios to form compounds.

Equal Volumes of all GasesContain Equal Numbers of Molecules

(when measured at the same conditionsof temperature and pressure)

Prior to Avogadro, it was assumed that the the reactioninvolved single atoms, like this:

Hydrogen{g) + Chlorine(g) ~ Hydrogen chloride(g)1 volume : 1 volume 2 volumes

Now, reasoned Avogadro, gases react in simple, whole-number volume ratios because each litre of gas has thesame number of molecules in it. Therefore, to get thevolume ratios shown above, each hydrogen molecule, andeach chlorine molecule, must have 2 atoms!

i.e. Hydrogen is H2(g) and Chlorine is Cl2(g)' and the correctequation is

Then, for the same reaction, scientists could measure themasses of these gases as well as volumes. This showed thatchlorine atoms must be about 35 times heavier thanhydrogen ... chemists were on the way to figuring out therelative atomic weights of elements, and being able tocalculate chemical quantities.

Although he did not invent the concept of the mole, wename the number of particles in 1 mole in Avogadro'shonour ...

Northmead High School SL#603217

Molar Volume of a GasIf 1 mole of any chemical species contains the samenumber of particles (Avogadro's Number) AND if equalvolumes of gases contain equal number of particles(Avogadro'S Hypothesis), then it follows that1 mole of any gas must occupy the same volume,if measured at the same temperature and pressure.

This volume is the "Molar Volume" and is the same forevery gas. It is measured at the standard set of conditionsknown as Standard Laboratory Conditions (SLC); 25°Cand 1 standard atmosphere of pressure.

Mole Calculations Involving GasesThis additional knowledge opens up the opportunity tocarry out quantity calculations which involve mass andvolumes of gases.

Example Problems1.If 15.65g of calcium carbonate (CaC03) was completelydecomposed by heat, what volume of carbon dioxidegas would be produced (if measured at SLC)?

SolutionAlways begin with the balanced equation for the reaction.

CaC03(s) •. CO2(g) + CaO(s)mole ratio = 1 : 1 : 1Moles of CaC03: n =..J.!L = 15.65 = 0.1564 mol

j\1},,f 100,09Mole ratio is 1 : 1, so moles of CO2 formed = 0.1564

~:. Volume of CO2 = 0.1564 x 24.8...... Molar Vol.

= 3.88 L (at SLC) of all gasesat SLC

2.What volume of hydrogen gas (at SLC) would beproduced if 10.00g of lithium metal was reacted withsulfuric acid?

Solution

2 Li(s) +2 :

•. H2(g) + Li2SO 4(aq)1 1

Moles of lithium: n = ..J.!L = 10.00 = 1.441 molMM 6.941

Mole ratio is 2:1, so moles of H2 = 1/2 X 1.441=0.7204

:. Volume of Hz = 0.7204 x 24.8= 17.9 L (at SLC)

1. Molar MassesCalculate the molar mass of:a) potassium b) kryptonc) tin d) bromine (Brz>e) nitrogen gas f) magnesium oxideg) sodium iodide h) iron(III) sulfidei) ammonia j) copper(lI) sulfatek) aluminium oxide I) glucose (C6H120J

2. No. of Moles in a Given MassHow many moles in:a) 100.0g of lead?b) 1OO.Ogof zinc?c) 100.0g of water?d) 100.0g of copper(lI) nitrate?e) 38.55g of magnesium fluoride?f) 60.00g of carbon dioxide?g) 1.000g of zinc oxide?h) 500.0g of flucose (C6H1PJ?i) 3.258 x 10- g of salt (sodium chloride)?j) 128.6g of ammonium carbonate?

3. Moles and Number of Particlesa) How many particles (atoms/molecules) in:i) 3 moles of water?ii) 2.478 mol of COiiii) 5 mol of salt?iv) 0.007862 mol of copperv) 1/1000 mol of helium

b) Convert between mass, moles and no.of particles.25 f' hI'i) If there are 8.800x10 atoms 0 till, ow many mo es 1S

this, and what would be the mass? .

ii) You have a sample containing 2.575x1024 molecules ofwater. How many moles is this, and what is its mass?

iii) If you weigh out 400.0g of water, how many moles isthis, and how many molecules are present?

iv) If you have 2.569g of pure nickel, how many atoms arethere?

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4. Mole Ratios in EquationsSodium reacts with water as follows:2N a + 2HzO •. Hz +

a) If 1 mole of sodium reacted, how many moles ofi) hydrogen formed? ii) water consumed?

b) If 0.25 mol of NaOH formed, how many moles ofi) sodium consumed? ii) hydrogen formed?

c) If 0.75 mole of hydrogen formed, how many moles ofi) sodium consumed? ii) NaOH produced?

Aluminium reacts with oxygen:4Al + 3 0z ~ 2Alz03

d) If 0.5 mole of AI used, how many moles ofi) Alum.oxide formed? ii) oxygen used?

e) If 0.1 mole of alum. oxide formed, how many moles ofi) aluminium used? ii) oxygen used?

5. Mass Quantities in Reactionsa) Calcium burns in oxygen to form calcium oxide:

2Ca + 0z ~ 2CaOIf 8.50g of calcium reacted, what mass of calcium oxidewould be formed?

b) Silver carbonate decomposes when heated:2AgzC03 ~ 2COz + 4Ag + 0z

If 20.0g of silver carbonate was decomposedi) what mass of silver metal would form?ii) what mass of CO2 would be produced?iii) what mass of 02 would be formed?

c) Aluminium reacts with hydrochloric acid:2Al + 6HCI ---.. 3Hz + 2AlC13

If 6.50g of aluminium reactedi) what mass of HCI would be consumed?ii) what mass of hydrogen gas produced?iii) what mass of aluminium chloride produced?

d) Tin reacts with steam as follows:

Sn(s) + 2HZO(g~ 2HZ(g) + SnOZ(s)

If 14.8g of tin reactedi) what mass of tin(lV) oxide would be formed?ii) What mass of steam would be consumed?iii) what mass of hydrogen would be produced?

6. Empirical Formulas from Mass Compositiona) A compound containing only copper and chlorine isdecomposed, and the masses measured to fmd the masscomposition:Mass of copper present = 12.84gMass of chlorine present = 7.16gi) Find the empirical formula.ii) Name the compound.

b) i) Find the empirical formula of a compound containingcarbon and hydrogen; a sample was found to contain 1.5gof carbon and O.5g of hydrogen.ii) Name the compound, given that its empirical andmolecular formulas are the same.

c) A compound was found to contain 30% nitrogen and70% oxygen by mass.i) Find the empirical formula.ii) It is later found that its molecular formula is a 2 timesmultiple of the empirical. Write the molecular formula.iii) Name the compound.

7. Volumes of Reacting Gases( Assume all are measured at same temperature & pressure)

2 HZ(g) + 0Z(g) ••. 2 HZO(g)

a) If you used 5 litres of hydrogen, how many litresi) of oxygen consumed?ii) of water vapour formed?

b) If you used 0.25 litres of oxygen, how many litres ofi) water vapour formed?ii) hydrogen consumed?

c) If tllls reaction produced 20 litres of steam, how manylitres ofi) hydrogen consumed?ii) oxygen consumed?

Ammonia gas isnitrogen

3 HZ(g)

d) In order to make 9 litres of ammonia, what volumei) of hydrogen needed?ii) of nitrogen needed?

e) If 0.6 litre of hydrogen reacted, what volumei) of ammonia formed?ii) of nitrogen need?

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8. Mass & Gas Volume Calculationsa) To "scrub" the air and remove poisonous COz on boardthe Space Shuttle, the air is continually pumped throughcanisters containing 5.0kg of litlllum oxide. The reaction is

LiZO(s) + COZ(~ LiZC03(s)

i) How many moles of litillum oxide in each canister?ii) How many moles of COz can this amount absorb?iii) What volume of COz(g) is tills? (measured at SLC)

b) Iron reacts with oxygen:4Fe(s) + 30Z(g) -... 2FeZ03(s)

i) If 10.0L of 0z at SLC reacted, what mass of iron(III)oxide would be formed?ii) If 100g of iron reacted, what volume of oxygen (at SLC)would be needed?

c) The electrolysis of water causes decomposition:2HzO (I) ••• 2HZ(g) + °Z(g)

i) If 1.00g of water was decomposed, what volumes ofeach gas (measured at SLC) would be formed?

In an electrolysis experiment, 50mL (0.050 L) of oxygenwas produced. (measured at SLC)ii) What volume of hydrogen (at SLC) was produced?iii) What mass of water must have been decomposed?

The formal definition of the mole is "the a) .of atoms in 12.00 grams of b) "One mole of any substance contains the same numberof c) The mass of 1 mole of anysubstance is equal to its d) .in grams. The actual number of particles in one mole ofanything is known as "e) .'sNumber" and has a value of f) .

In a balanced chenllcal equation, the "balancing numbers"(coefficients) may be interpreted as being g) ............................... of reactants and products.

By converting between the h) of substancesand the number of i) , it becomes possibleto calculate all the quantity relationships during a chenllcalj) From the mass composition it is alsopossible to determine the k) formula ofcompounds.

Historically, the mole concept arose from the work of 2men: The Frenchman 1) - .discovered that "the m) of gases in chemicalreactions always show simple, n) .ratios to each other". Soon after, the Italian0)................................................. suggested that "Equalp) of all gases contain q) .numbers of r) (when measured at thesame conditions of s) and )The standard conditions usually used are known ast)...................... (abbreviation) and is a pressure ofu) and temperature v) °c.

Ores and Minerals... and now back to the metals.

Minerals are naturally occurring compounds. "Rocks" aremixtures of various minerals. Most minerals are latticestructures, both ionic and covalent. Some very commonminerals include:

o Silica, which is chemically silicon dioxide (SiOz) and is themost common mineral on Earth. Other compounds areoften included in the silica lattice to make "silicate"minerals. These occur in virtually all rocks.o Calcite, which is calcium carbonate (CaC03) is the mainmineral in limestone and marble.

Some minerals contain significant quantities of metal(s),chemically combined in the compound.

Ores are rocks and/or minerals from which it 1S

economically worthwhile to extract a desired metal.

It is the economic part of this definition which is criticaLFor example, there are many rocks and minerals thatcontain significant amounts of iron and aluminium. Theseare not "iron ore" or "aluminium ore" unless it iseconomically worthwhile to mine and process them to getthe metaL

What Makes It Economically Worthwhile?Basically, economic feasibility is the balance between:

o the Commercial Price for which the metal can be soldando the Production Costs of mining and transporting theare, and chemically extracting and purifying of the metal.

Another factor is the abundance of the metal and its oreson Earth. For example, iron is relatively cheap because it isvery common in huge deposits of iron ores. Platinum isvery rare, so it commands a high price. This makes itworthwhile to mine even very low-grade ores. A low-gradeiron are would not be worth mining!

The Importance of PredictingYield from an Ore

The whole situation of economic feasibility makes thescience of Analytical Chemistry vital in the mining andmetals industry.

Mining operations cost millions of dollars to set up. To doso, the operators need to be sure that the ore containsenough metal to be profitable. Chemical analysis in thelaboratory is used to measure the mineral content of theore body, to predict the final yield of the metal.

Ores are Non-Renewable ResourcesMinerals and ores have been formed over millions andbillions of years of geological processes on Earth.

Because of that time-frame, the ores are non-renewable inthe sense that once we use them up, they cannot bereplaced.

There is no immediate concern for running out of themost important ores, but unlimited exploitation of anynon-renewable resource is:

o irresponsible, to future generations.o unsustainable, because all non-renewable things musteventually run out.

o economically stupid, because it may be cheaper to re-useand recycle, dlan to constantly extract "new" materials.

o environmentally damaging, because mining and metalsmelting have a history of pollution and ecosystemdestruction.

In the not-too-distant future it may become economicallyworthwhile to begin "mining" the old rubbish dumpsaround our cities, to recover dle discarded metals insociety's garbage.

Case Study:Extraction of Copper from its Ores

Copper Oresinclude a variety of compounds of copper, including:

• coppe,r(I) sulfide, Cu2S• copper(II) hydroxide mixed withcopper(II) carbonate, Cu(OH}z.CuC03

Froth Flotation to Concentrate the OreThe ore is crushed into a powder and the copperminerals are separated from the silicates by a process of"Froth Flotation" which relies on differences in"wettability" and density.

These compounds usually occur as thin "veins" of blue-green minerals embedded in masses of worthless silicaterock.

The copper content of the entire ore body might be only3% or less. Therefore, the first step after mining is toseparate the copper minerals from the "rock".

Compressed air creates a froth of bubbles in a detergentsolution.

Chemistry of SmeltingThe concentrated copper minerals now undergoDecomposition Reactions.

Copper minerals, sprayed with a special oil, cling to thebubbles and are carried upwards to overflow with d1efroth.

In Australia, the main copper ores contain copper(I)sulfide. If tllls is heated in a furnace supplied witl1 plentyof air the reaction is:

Silicate minerals are wetted by the water and, beingdenser, sink to the bottom.

Copper(I) sulfide + oxygen... Copper + Sulfur dioxideCu2S + 02 • ZCu + S02

The collected froth is then treated to separate tl1e oil anddetergent for re-use.

Sulfur dioxide is a serious pollutant if releasedfrom the smelter.These days it is collected and used tomanufacture sulfuric acid... a useful by-product.

Final Purification by ElectrolysisThe major use of copper is for electrical wiring. For d1is it needs to be 99.9% pure.

Copper is purified by electrolysis:

The impure copperis immersed inCuSO 4 solution andelectrified:

ImpureCopperdissolvesintosolution

~-C +2 . I"U Ions '.

migrate throug~CuS04 solution ~ I

~J

After nligratingtluough tl1e solution,tl1e ions are re-deposited as purecopper metal on tl1eother electrode:

The copper dissolvesinto d1e solution, butimpurities do not.

PureCopperdepositsonelectrode

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The Case for RecyclingThe point that mineral ores are non-renewable has alreadybeen made. Eventually, any non-renewable resource mustrun out, so recycling is inevitable.

There is also a strong environmental case for recycling ofmetals, especially aluminium.

Producing the electricity usually involves the burning ofcoal at a power station. The burning of fossil fuels like coalis a major contributor to the "Greenhouse Effect" whichmany scientists are now convinced is causing massiveclimate changes to the entire Earth.

Recvcling aluminium requires about 7kI of energy, a saving~--'" of about 96% in energy and environmental impact!

Extracting aluminium from its ore reqUires about 200k](kilojoules) of energy per kg of metal. This energy ismainly in the form of electricity, which is needed in hugequantities for the electrolytic smelting process.

"Minerals" are naturally occurring a) : .which are mixed together in rocks.

An "ore" is a b) from which it isc) worthwhile to extract a desiredd) .

Whether it is worthwhile (or not) to mine an ore depends onthe balance between the e) .and the f) of ml111ng,transporting and g) the metal.

h) analysis of an ore deposit is vital topredict the i)..................................... from the ore, todetermine if it is worth mining.

Ores are j) resources becauseonce used, they cannot k) .due to the immense time it takes for 1) .processes to form them.

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Most local councils now operate "Recycling Centres"which can sort out paper, glass, plastic, etc from ourgarbage, as long as we remember to put recyclables in thecorrect bin.

Aluminium (mainly drink cans) collected this way isreturned to scrap-metal businesses which clean and re-meltthe metal to return it to manufacturing industry for re-use.

Copper ores contain compounds such as m) ............................. and .After mining, the ore is crushed, then concentrated by"n)........................... .. ". This processuses a froth of bubbles to separate the0) density copper compounds from theworthless rock which is mainly p) .minerals.

The "smelting" process involves q) .reactions. For a sulfide ore, it reacts with r) .to form s) metal and t) .gas.

The fInal step is to u) the copper by aprocess of v) .

There are many good reasons to w) .metals, especially x) which requireslarge amounts of y) energy to extractfrom its ore. Producing the electricity required is often doneby burning z) fuels such as aa) .This contributes to the "ab) .Effect", responsible for global climate changes. Recyclingaluminium requires only a fraction of this energy.

CONCEPT DIAGRAM ("Mind Map") OF TOPICSome students find that memorizing the OUTLINE of a topic

helps them learn and remember the concepts and important facts.Practise on this blank version.

METALS

Practice QuestionsThese are not intended to be "HSC style" questions, but tochallenge your basic knowledge and understanding of thetopic, and remind you of what you NEED to know at theK.ISS. Principle leveL

When you have confidently mastered this level, it isstrongly recommended you work on questions from pastexam papers.

1.Which list shows metals used by humans in the correctchronological order of their history of usage?A. bronze, aluminium, ironB. copper, bronze, ironC. gold, iron, bronzeD. copper, steel, bronze

2.Which list correctly identifies an alloy, and the elements itcontains?A. Steel; iron and tinB. Bronze; tin and zincC. Solder; copper and leadD. Brass; copper and zinc

3.The metals used by humans have changed over the courseof history. The availability of new metals has often beendependent on the:A. availablity of energy to extract metals from ores.B. discovery of new minerals as people explored the world.C. invention of new alloys.D. development of new technologies to use the metals.

4.A metal which reacts readily and vigorously with oxygen,water and dilute acids would probably:A. have a high value for 1st ionization energy.B. be from the "Transition" block of the Periodic Table.C. have a very low 1st ionization energy.D. be located at extreme right of the Periodic Table.

5.If nickel reacted with sulfuric acid, the products of thereaction would be:A. hydrogen gas and nickel sulfateB. carbon dioxide gas and nickel sulfate.C. nickel sulfide and hydrogen gas.D. sulfur dioxide gas and nickel hydroxide.

6.During the reaction in Q5, the basic underlying changeoccurnng IS:

A. the breaking covalent bonds.B. the transfer of electron(s) from one species to another.C. chemical changes in "spectator ions".D. physical dissolving of metal in the acid.

7.The scientist most responsible for the development of thePeriodic Table was:A. AvogadroC. Gay-Lussac

B. NewlandsD. Mendeleev

8.Element "X" is in Group 2 and element "Y" in Group 7.

If X& Yformed acompound,you wouldexpect it to be

j--"t

r'.-T-'.t i

~n~m+1Ejg=fftj~A. ionic, with formula ~ YB. covalent, with formula ~ YC. ionic, with formula :>"''Y 2D. covalent, with formula Y2X

9.If the elements "X" & "Y" in Q8 lie in the same period ofthe table, you would expect:A. X to have a smaller radius than YB. Y to have a higher electronegativity than X.C. X to have a higher 1st ionization energy than YD. Y to have a higher melting point than X.

10.The reason for the trend in atomic radius as you moveacross a period to the right, is:A. increasing nuclear charge.B. addition of extra electron shells.C. decreasing attraction of electrons to the nucleus.D. increasing mass of the atoms.

11.An atom of argon is about twice as heavy as an atom ofneon. You would expect:A. a mole of argon to contain about half as many atoms asa mole of neon.

B. equal masses of each element to contain about the samenumber of atoms.

C. 2g of argon to contain about the same number of atomsas Ig of neon.

D. the molar mass of neon to be about twice tlle molarmass of argon.

12.Which line shows correctly the molar mass (to the nearestgram) of the named substance?A. water, 18gB. carbon dioxide, 28gC. oxygen gas, 16gD. helium gas, 8g

13.I\luminium reacts with oxygen to form ahuninium oxide.

4 AI + 3 02 •. 2 Alz03

If 1 mole of aluminium (about 27g) was to be reacted, youwould need how many moles of oxygen gas?A. 0.75 mol B. 3 molC. 1 mol D. 1.3 mol

14.Avogadro's number can be described by the abbreviation NA'If you had 2 moles of me dune (CHJ, then the number ofhydrogen atoms present is:A. 2 x NAB. 4 x NAC.8xNA D.10xNA

15.Carbon monoxide gas reactscarbon dioxide gas as follows:

2C:0(g) + 02(g)--------"••--

If 100mL of carbon dioxide was produced, then the totalvolume of reactants (all measured at the same temp. &pressure) before the reaction would have been:A. 100mL B. 150mLC. 50mL D. 250mL

16.The "smelting" of a metal ore always involves:A. separatlll.g the metal-containing mineral from the rock.B. decomposing a compound of the metal.C. purifying the extracted metal by electrolysis.D. all of the above.

Longer Response QuestionsMark values shown are suggestions only, and are to giveyou an idea of how detailed an answer is appropriate.

17. (5 marks)Give an example of

a) a metal used in its elemental state, andb) a non-ferrous alloy (naming its components)

in common use. For each, relate the properties of the metalto its particular use(s).

18. (3 marks)Give a reason whya) metal tools are superior to stone tools.b) iron replaced bronze in the history of metallurgy.c) aluminium did not come into common use until the 20thcentury.

19. (6 marks)The most common metal in use today is steel, which comesin a variety of forms, with different properties and uses.Compare 3 different types of steel, stating the compositionof each and relating its properties to a common use.

20. (5 marks)Give an outline of an experiment you have done toinvestigate the relative chemical activity of some metals.Include the observation(s) you made to assess metalactivity, and state the conclusion(s) reached.

21. (6 marks)Write a balanced symbol equation for the reaction of:a) magnesium with hydrochloric acid.b) calcium with water (reacts at room temperature).c) potassium with oxygen.

22. (4 marks)When barium metal reacts with an acid there is an exchangeof electrons such that hydrogen gas and barium ions areformed.\'V'rite 2 "half-equations" to show clearly the speciesgaining, and the species loslll.g, electrons.

23. (4 marks)a) Write anionization of

equation (including states) for the firsti) magnesiumii) oxygen

b) Describe how the Activity Series of Metals is related todl.e values of 1st Ionisation Energy.

24. (5 marks)a) Sketch a graph (values are not required) to show thegeneral changes in melting points of the elements acrossone period of the Periodic Table.b) Briefly explain the general trend shown in your graph.

25. (marks)a) Write equations (including states) to describe the

i) 1stii) 2nd

and iii) 3rd ionisations of potassium.b) At which ionization would you expect a huge lll.CreaSeinthe ionization energy? Explain your answer.

26. (6 marks)a) Write a balanced equation for the reaction of aluminiummetal with hydrochloric acid.b) If 6.58g of aluminium reacted fully, calculate:

i) the number of aluminium atoms involved.ii) the mass of aluminium chloride formed.iii) the volume of hydrogen gas (at SLC)

27. (4 marks)It was found by experiment that a compound containingonly tin and oxygen, contained 88% tin, by mass.Showing your working, determine the empirical formula forthis compound, and give its correct chemical name.

28. (4 marks)In the reaction of nitrogen and hydrogen gases to formammonia gas, it was found by experiment that 300mL ofhydrogen reacted completely with 100mL of nitrogen.200mL of ammonia gas was produced. All the gas volumeswere measured at a pressure of 10 standard atmospheresand 1S0°C.a) Write a balanced equation for the reaction.b) Explain how the experimental measurements are 1nagreement with Gay-Lussac's Law:

29. (S marks)a) Differentiate between a "mineral" and an "ore".b) Outline the role of Chemical Science in assessing theeconomic feasibility of mining a mineral resource.c) Briefly discuss the sustainability of using the Earth'smineral resources, and outline a strategy for conservation.

30. (8 marks)a) Give the name and formula for a compound commonlyfound in copper ores.

b) Name, and briefly describe the process by which acopper ore is concentrated and separated from thesurrounding "rock".

c) Write a chemical equation to describe the reaction whichoccurs in the smelting of the ore. (Involving the compoundyou named in part (a»

d) Name the process by which the smelted copper ispurified, and relate the need for purification to a commonuse of the metaL

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Answer Section

Worksheet 1a) stone or wood/bone b) goldc) decoration/jewellery d) coppere) roasted by fire f) copper and ting) bronze h) hard and strongi) brittle j) a saw bladek) iron I) harder and strongerm) temperature/energy n) coal0) steel p) carbonq) aluminium r) energys) ores t) ironu) steel v) cheap/economicalw) hard and strong x) mildy) stainless z) copper and zincaa) solder ab) tin and leadac) plumbing and electronicsad) lightweight ae) corrosionaf) drink cans/window frames/aircraft constructionag) copper ah) conductivityai) ductile aj) decompositionak) endothermic al) copperam) aluminium an) electricityao) metal ap) energy

Worksheet 2Part Aa) oxidec) hydrogene) hydrogeng) differenti) potassium and sodiumk) copper and goldm) slowly0) loseq) covalents) Hzu) Reductionw) hydrogeny) Ionisationaa) gasac) higherad) gold used in electronics, because it will not corrode.

b) :METAL OXIDEd) hydroxide (or oxide)f) salth) activityj) leftI) iron and tin/lead/zincn) electronsp) hydrogenr) hydrogent) loss of electronsv) oxidizedx) reducedz) remove one electronab) low

Part B Practice Problems1.a) Pb + 0z •. PbOz

2.a) Li, Fe, Pbb) Lithium

3.a) calcium + water --.- hydrogen + calcium hydroxideCa + 2HzO --~ •.- Hz + Ca(OH}z

b) Tin + water ----0"- hydrogen + tin(II) oxideSn + HzO ---11"- Hz + SnO

hydrogen + zinc sulfate•. Hz + ZnS04hydrogen + calcium chloride•. Hz + CaClz

Zn + HZS04b)Ca + 2HCI

c) Barium + nitric acidBa + 2HN0

3-....

d) Iron + hydrochloric acidFe + 2HCI •.

5.a) the metals: Zn, Ca, Ba, Feb) hydrogen ions (from the acid)c) sulfate, chloride and nitrate ions.

Worksheet 3Part Aa) Dobereiner b) Newlandsc) Octaves d) Mendeleeve) Periodic Table f) been discoveredg) left gaps h) predicti) almost identical to the predictionsj) decreases k) semi-metals & non-metals1)increase m) decreasen) Transition 0) semi-metalp) inert q) rightr) identical s) metalst) ionic u) positivev) covalent w) covalentlyx) gain y) negativez) bottom aa) upwardsab) right ac) topad) down and left ae) decreasesaf) more ag) nucleusah) increases ai) Ionisationaj) increase ak) removeal) decrease am) lessan) remove ao) higherap) increases aq) Electronegativityar) attract as) fluorineat) left au) down

Part B1.a) 1st +

Ca(g) -.. Ca (g) + e

+ +z2nd Ca (g) -.. Ca (g) + e

3 d C +z ----- C +3 +r a (g)------- a (g) e

h +3 +44t Ca ()-.. Ca (g) + e-b) Between 2n~ and 3rd, because 3rd ionisation takes anelectron from an inner orbit.2.a) i) decreasingb) i) increasing

H= fluorinec) i) increasing

H = helium

ii) increasingii) decreasing

L= franciumii) decreasing

L = francium

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Worksheet 4Part A1. Molar Massesa) 39.10g b) 83.80g c) 118.7gd) 159.8g e) N2 = 28.02g f) MgO = 40.31gg) NaI= 149.9 h) Fe2S3=207.9g i) NH3=17.03gj) CuS04=159.6g k) AIP3=102.0g I) 180.2g

2. Moles in a Given Mass use n = m/MMa) n= 100.0/207.2 = 0.4826 molb) n = 100.0/ 65.39 = 1.529 molc) n = 100.0 / 18.016 = 5.551 mold) n= 100.0/251.12 = 0.3982 mole) n = 38.55 / 62.31 = 0.6187 molf) n = 60.00 / 44.01 = 1.363 molg) n = 1.000/ 81.39 = 0.01229 molh) n = 500.0 / 180.2 = 2.775 moli) n = 3.258x10·3/ 58.44 = 5.575 x 10.5molj) n = 128.6 / 96.094 = 1.338 mol

3. Moles & Particlesa) use n = N/NA and N= n x NA. _ 23 241) N - 3 x 6.022xl0 = 1.807x10 molecules..) N 2 7 23 2411 =.4 8 x 6.022x10 = 1.492x10 molecules...) N 5 0 023 24 .111 = x 6. 22xl = 3.011x10 "sets" of Ions.. ) N - 23 21IV - 0.007862 x 6.022x10 = 4.734xlO atoms

23 20V)N = 1/1000 x 6.022xl0 = 6.022xl0 atoms. ~ nb) 1) n = N/NA = 8.800x10 /6.022x10 = 146.1molm = n x MM = 146.1xl18.7 = 172340g(=17.34kg)ii) n = N/NA = 2.575x1024/6.022x10 3 = 4.276 mol

m = n x MM = 4.276 x 18.016 = 77.04giii) n = m/MM = 400.0/ 18.016 = 22.20 mol23 25N = n x NA = 22.20 x 6.022x10 = 1.337xl0 moleculesiv) n = m/MM = 2.569/58.69 = 0.04377 mol_ _ n nN - n x NA - 0.04377 x 6.022x10 = 2.636x10 atoms23 23v) n = N/NA = 2.500xl0 /6.022x10 = 0.4151 molm = n x MM = 0.4151 x 32.07 = 13.31g

4. Mole ratios in Equationsa) i) 0.5 mol ii) 1 molb) i) 0.25 mol ii) 0.125 molc) i) 1.5mol ii) 1.5 mold) i) 0.25 mol ii) 0.375 mole) i) 0.2 mol ii) 0.15 mol

5. Mass Quantities in Reactionsa) n(Ca) = m/MM = 8.50/40.08 = 0.212 mol:. n(CaO) = 0.212 molm(CaO) = n x MM = 0.212 x 56.08 = 11.9g

b) n(Ag2C03) = m/MM = 20.0/275.81 = 0.0725 moli) :. n(Ag) = 0.0725 x 2 = 0.145 molm(Ag) = n x MM = 0.145 x 107.9 = 15.6g

ii) :. n(CO~ = 0.0725 molm(CO~ = n x MM = 0.0725 x 44.01 = 3.19g

iii) :. n(O~ = 0.0725 / 2 = 0.03625 molm(O~ = n x MM = 0.03625 x 32.00 = 1.16g

c) n(AI) = m / MJ.VI= 6.50/26.98 = 0.241 moli) :. n(HCl) = 0.241 x 3 = 0.723 mol

m(HCl) = n x MM = 0.723 x 36.458 = 26.4gii) :. n(H~ = 0.241 x 3/2 = 0.3615 mol

m(H~ = n x 11M = 0.3615 x 2.016 = O.729giii) :. n(AICI3)= 0.241 mol

m(AICl3)= n x MJ.VI= 0.241 x 133.33 = 32.1g

Northmead High School SL#603217

d) n(Sn) = m / MM = 14.8/118.7 = 0.125 moli) :. n(SnO~ = 0.125 mol

m(SnO~ = n x MM = 0.125 x 150.7 = 18.8gii) :. n(HzO) = 0.125 x 2 = 0.250 mol

m(HzO) = n x MM = 0.250 x 18.016 = 4.50giii) :. n(H~ = 0.125 x 2 = 0.250 mol

m(H~ = n x MM = 0.250 x 2.016 = 0.504g

6. Empirical Formulasa) i) Coppermasses 12.84gNo moles = 12.84/63.55

0.2020ratio = 1:. emp. formula is CuCI

ii) Copper(I) chlorideb) i) Carbonmasses 1.5gNo moles = 1.5/12.01

0.1250.125/0.125

= 1ratio _ 1:. emp. formula is CH4

ii) methanec) i)

: Chlorine7.16g7.16/35.450.20191

: Hydrogen0.5g0.5/1.0080.4960.496/0.1253.964

Nitrogen30%30/14.Q12.142.14/2.141

_ 1:. emp. formula is NOz

ii) 2 x (NO~ = N204iii) dinitrogen tetra-oxide

: Oxygen70%70/164.3754.375/2.142.042

massesNo moles =

7. Volumes of Reacting Gasesa) i) 2.5L ii) 5 Lb) i) 0.5 L ii) 0.5 Lc)i)20L ii)10Ld) i) 13.5 L ii) 4.5 Le) i) 0.4 L ii) 0.2 L

8. Mass & Gas Volumea) i) n(Lip) = m/MM = 5,000/29.882 = 167 molii) n(CO~ = 167 moliii) v(CO~ = 167 x 24.8 = 4.14x103 L (>4,000L !)

b) i) n(O~ = 10.0/24.8 = 0.403 mol:. n(Fep3) = 0.403 x2/3 = 0.269 molm(Fe203) = n x MM = 0.269 x 159.7 = 42.9g

ii) n(Fe) = m/MM = 100/55.85 = 1.79mol:. n( O~ = 1.79 x 3/4 = 1.34molV(O~ = 1.34 x 24.8 = 33.2 L

c) i) n(H20) = m /MM = 1.00/ 18.016 = 0.0555 mol:.n(H~ = 0.0555, v(H~ = 0.0555 x 24.8 = 1.38 L

and n(O~ = 0.0555/2, v(O~ = (0.0555/2) x24.8=0.688Lii) use Gay-Lussac's Law: v(H~ = 100mL (0.10 L)iii) n(H~ = 0.10 / 24.8 = 0.00403 mol:. n(H20) = 0.00403 molm(Hp) = n x MM = 0.00403 x 18.016 = O.073g

keep it simple science

Worksheet 4Part Ba) numberc) particlese) Avogadro'sg) ratio of molesi) moles (particles)k) empiricalm) volume0) Avogadroq) equals) tempera hue & pressureu) 1 standard atmosphere

b) carbon (carbon-12)d) formula ~~ssf) 6.022 x 10h) massj) reactions1)Gay-Lussacn) whole-numberp) volumesr) molecules/particlest) SLCv) 25

a) compounds b) mineralc) economically d) metale) commercial price f) production costg) extracting (smelting) h) Chemicali) yield j) non-renewablek) be replaced 1)geologicalm) copper(I) sulfide & copper carbonate/hydroxiden) Froth-flotation 0) lowerp) silicate q) decompositionr) oxygen s) coppert) sulfur dioxide u) purifyv) electrolysis w) recyclex) aluminium y) electricalz) fossil aa) coalab) Greenhouse

Part AloB2. D3.A4. C

Multiple Choice5. A 9. B 13.A6. B 10. A 14. C7.D 11.C 15.B8. C 12. A 16. B

Longer ResponseIn some cases there may be more than onecorrect answer possible. The following "model"answers are correct, but not necessarily perfect.

17.a) Copper. Used for electrical wiring, due to its excellentconductivity and high ductility.b) Solder, an alloy of tin & lead. Used for joining pipes inplumbing, and joining wires in electronics, because of itsvery low melting point.18.a) not brittle/ can be re-sharpened/ shape possiblities (saw)b) Iron is stronger and harder ... tools are superior.c) Needs electricity for smelting.19.Mild Steel (0.2% carbon). Used for car bodies & sheetmetal, because it is strong but very malleable.Tool Steel (1.5% carbon). Used for hammers, drills, etcbecause it is very hard and strong.Stainless Steel (20% nickel & chromium). Used for foodutensils and medical equipment because it resists corrosionand is very hygenic.20.Small pieces of metal added to dilute acid in test tubes.(To keep expt. fair, the acid must be same strength, andmetal pieces same size.)Observe the rate of gas production to assess reactivity.Conclusion: order of activity is: Mg > 2n > Fe > Pb > Cu

21.a) Mg + 2HCI

Ba •. Ba+z + 2e+2H + 2e ---.. Hz

(Barium lost, hydrogen ions gained)23.a) i) Mg(g) • Mg+(g) _ + eii) 0(g) •• 0+ , + e

b) The lower the ist Ionisa~on Energy the more active themetal, because the metal readily loses electron(s) to enter areaction.24a) graph ~b) At the beginning of a '15period (left) the elements ';;,are soft metals with c::Emoderate to low mp's. ClI

::'EMoving right, the mp's riseto a maximum at a transitionmetal, or semi-metal. Then mp's fall rapidly at the non-metals. Lowest values are tl1.einert gases on far right.25. + -a) 1st: K( ) •. K (I) + e2nd: K+ g.. K+z +g e-3 d· (g) K+z (g) K+3 + -r . (g). (g) e

b) Between 1st & 2nd, because the 2nd lOnization involvesan electron from an inner orbit, which will require a bigincrease in energy to remove.26.a) 2Al + 6HCI ---.. 3Hz + 2AlCl3b) n(AI) = m / MM = 6.58 / 26.98 = 0.244 moli) N(Al)= n x NA=0.244x6.022xl0

z= 1.47xl0Z3atomsii) n(AICl3) = 0.244 molm(AICl3) = n x MM = 0.244 x 133.33 = 32.5giii) n(Hz) = 0.244 x 3/2 = 0.366 molV(Hz) = 0.366 x 24.8 = 9.08 L

Tin Oxvgen% mass 88 12moles 88/118.7 12/16.00

0.74 0.75~ 1 1

empirical formula is SnO. Tin(II) oxide28.a) Nz + 3Hz •. 2NH3

b) volumes = 100mL 300mL 200mLVol. ratio = 1 3 2

The volumes of the gases are in a simple, whole numberratio to each other. This is Gay-Lussac's Law.29. a) A mineral is a naturally-occurring crystalline compound.An are is a mineral which is economically worth miningto extract a metal from. All ores are minerals; not allminerals are ores.b) Chemical analysis allows an ore body to be analysed topredict the yield of metal.c) Ores are non-renewable resources, and once usedcannot be replaced. Therefore, it is wise to conserve theseresources by recycling metals wherever possible.30. a) Copper(I) sulfide, CUzS.b) Crushed ore is separated by "froth flotation". Lowdensity ore is carried in a detergent froth, while silicatesfall to the bottom.c) CUzS .+ 0z • 2Cu + SOzd) ElectrolysIs. Copper needs to be very pure for Its mainuse in electrical wires. If impure, conductivity is lower.