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National 4 & 5 Chemistry Metal Chemistry, Electricity & Chemistry,Examples Answers

NATIONAL 4 AND NATIONAL 5 CHEMISTRY

Unit 3: Chemistry in Society

METAL CHEMISTRY & ELECTROCHEMISTRY

PRACTICE EXAMPLES BOOKLEN4/5 METAL REACTIVITY AND DATE OF DISCOVERY N4/5

Q1) Using the N5 Chemistry Data Booklet; complete the REACTIVITY SERIES OF METALS with the Date of Discovery.

REACTIVITY SERIES OF METALS

document.docx of 18 5-May-23


METAL DATE OF DISCOVERY

potassium (K) 1807

sodium (Na) 1807

lithium (Li) 1817

calcium (Ca) 1808

magnesium (Mg) 1808

aluminium (Al) 1825

zinc (Zn) Ancient

iron (Fe) Ancient

tin (Sn) Ancient

lead (Pb) Ancient

copper (Cu) Ancient

mercury (Hg) Ancient

silver (Ag) Ancient

gold (Au) Ancient

Q2) What conclusion can be drawn from the metals reactivity and the date it was discovered. The more reactive the metal the later in history it was discovered, this would be due to the level of technology and Chemistry knowledge needed for extraction.

N4/5 METALS AND THEIR PROPERTIES N4/5

1. Match the following terms to their definitions

electrical conductor lustrous malleablesonorous flexible ductile thermal conductor

lustrous All metals are shiny when polished or freshly cut

flexible Metals do not break – they bend

ductile Metals can be drawn into wires

malleable Metals can be hammered into sheetsdocument.docx of 18 5-May-23


sonorous Metals ring like a bell when hit - they do not make a dull thud

Electrical conductor All metals conduct electricity

Thermal conductor Metals allow energy to flow through them, causing heating

2. Which of the following are NOT properties of most metals?

strong magnetic high melting pointbrittle hard

3. Metal application is based on the properties that the metal or alloy will have. Identify the properties of the metals which are important for the following uses.


1. Copper, iron, steel or aluminium are obviouslygood conductors of heat and malleable. Copper isone of the best conductors of heat but if you want apan made fully out of copper it would be expensivefor the consumer. Aluminium is also a metal thatconducts heat very well and isn't too expensive. Lowreactivity is important because acid is producedwhen cooking. Stainless steel is a good metalbecause it is tough, so withstands dishwashers anddamages. It is non-reactive which means certainacidic foods won't be discoloured, which may be thecase with aluminium pans. A solution to this would bea stainless steel outside and have a copper oraluminum core. This way it still conducts heat well,doesn't cost too much and because it only has analuminum core, the metal won’t change the food.

5. Bronze is used because it has the best sound, tone, and resonance as well as multiple harmonics. The tone and vibrato are gorgeous. Other metals can be used but are inferior in sound. The Liberty Bell is bronze. Sonorous. It also has high corrosion resistance.

3. In 1943, Richard James, a naval mechanical engineer stationed at the William Cramp and Sons shipyards in Philadelphia, was developing springs that could support and stabilize sensitive instruments aboard ships in rough seas. James accidentally knocked one of the springs from a shelf, and watched as the spring "stepped" in a series of arcs to a stack of books, to a table top, and to the floor, where it re-coiled itself and stood upright. James' wife Betty later recalled, "He came home and said, 'I think if I got the right property of steel and the right tension; I could make it walk.'" Flexible, ductile and malleable.

2. Copper is so ductile becausethe layers of positive copper ionscan slip over each other whilst stillbeing held together by the 'sea' ofde-localised electrons. Copper hasthe best electrical conductivity ofany metal, except silver. A goodelectrical conductivity is the sameas a small electrical resistance.

4. Silver and gold are very softmetals and can be moulded intodifferent shapes they are very pureforms of metals so there are verylittle impurities. They are not veryreactive in open atmosphere i.ealmost inert metals. They are ofcourse lustrous.

“All that is gold does not glitter,

Not all those who wander are lost….” J.R.R. Tolken

7. Pure tungsten has some amazing properties including the highest melting point (3422 ºC), lowest vapour pressure, and greatest tensile strength out of all the metals. Because of these properties it is the most commonly used material for light bulb filaments. Flexible, ductile, thermal and electrical conductor.

8. Testing of different material blades like High Carbon Steel, Low Alloy Steel, Bi-metallic blade, High speed Steel blades for their hardness, Cutting time performance, Wear Resistance, Tensile Strength and performance under buckling is essential in the manufacture of high quality tools like a cutting saw.

6. Most of the engineering materials are alloys for strength and other desired properties. Steel, an alloy of iron, has various types depending on the alloying elements. It is strong and can withstand a considerable force (high compression strength in comparison to concrete which is brittle. That is why concrete is reinforced with steel.)

9. Lead lasts an average of more than

three times longer than other roofing and

flashing products. Lead is resistant to

corrosion from the atmosphere, salt water,

most natural chemicals, and UV

degradation. Lead is recyclable and can be

re-used. Sheet lead can be tightly dressed

around junctions and penetrations and is

the only material that can protect these

areas from water penetration. Lead is able

to cope with wide ranging temperature

fluctuations, and its malleability ensures no

cracking. Sheet lead installation is not

http://en.wikipedia.org/wiki/William_Cramp_and_Sons

http://en.wikipedia.org/wiki/Richard_T._James


N4/5 REACTION OF METALS WITH OXYGEN N4/5

1. Copy and complete the following word and formula equations.(N5 students should balance the formula equations.)

(a) metal + oxygen Metal oxide

(b) aluminium + oxygen Aluminium oxide

4Al + 3O2 2 Al2O3

4Al(s) + 3O2(g) 2(Al3+)2(O2-)3(s)

(c) magnesium + oxygen Magnesium oxide

2Mg + O2 2MgO 2 Mg(s) + O2(g) 2Mg2+O2-

(s)

(d) Lithium + oxygen Lithium oxide

4Li + O2 2Li2O 4Li(s) + O2(g) 2(Li+)2O2-

(s)

(e) Copper + Oxygen Copper(ii) Oxide

Cu2Cu(s)

++

O2

O2(g)

CuO2Cu2+O2-

(s)


7. Pure tungsten has some amazing properties including the highest melting point (3422 ºC), lowest vapour pressure, and greatest tensile strength out of all the metals. Because of these properties it is the most commonly used material for light bulb filaments. Flexible, ductile, thermal and electrical conductor.

8. Testing of different material blades like High Carbon Steel, Low Alloy Steel, Bi-metallic blade, High speed Steel blades for their hardness, Cutting time performance, Wear Resistance, Tensile Strength and performance under buckling is essential in the manufacture of high quality tools like a cutting saw.

10. Partly because brass does not corrode in seawater and partly because brass is not magnetic and so does not interfere with the compass needle. Malleable and flexible.

9. Lead lasts an average of more than

three times longer than other roofing and

flashing products. Lead is resistant to

corrosion from the atmosphere, salt water,

most natural chemicals, and UV

degradation. Lead is recyclable and can be

re-used. Sheet lead can be tightly dressed

around junctions and penetrations and is

the only material that can protect these

areas from water penetration. Lead is able

to cope with wide ranging temperature

fluctuations, and its malleability ensures no

cracking. Sheet lead installation is not

11. Strong strength to weight ratio. While the same can be said of exotic metals like titanium, aluminum is much cheaper. Low density 2.70g/cm3. Malleable. Flexible.

12. Lead is a fairly cheap metal, which is good for fishing weights that can get lost. It is a soft malleable metal and resistant to corrosion. Lead has a high density 11.3g/cm3. The other metals are not as good as lead but share some of the characteristics above. The reason lead is being replaced is lead is toxic.


2. Write balanced ionic equations for the above reactions with state symbols.

N4/5 REACTION OF METALS WITH WATER N4/5


(a) metal + water Metal hydroxide

+ hydrogen

(b) calcium + water Calcium hydroxide

+ hydrogen

Ca + 2H2O Ca(OH)2 + H2

Ca(s) + 2H2O(l) Ca2+(OH-)2(aq) + H2(g)

(c) sodium + water Sodium hydroxide

+ hydrogen

2Na + 2H2O 2NaOH + H2

2Na(s) + 2H2O(l) 2Na+OH-(aq) + H2(g)

(d) lithium + water Lithium hydroxide

+ hydrogen

2Li + 2H2O 2LiOH + H2

2Li(s) + 2H2O(l) 2Li+OH-(aq) + H2(g)

(e) potassium + water Potassium hydroxide

+ hydrogen

2K + 2H2O 2KOH + H2

2K(s) + 2H2O(l) 2K+OH-(aq) + H2(g)




N4/5 REACTION OF METALS WITH ACID N4/5


(a) metal + acid Salt + hydrogen

(b) lead + Hydrochloric acid

Lead(ii) chloride

+ hydrogen

Pb + 2HCl PbCl2 + H2

Pb(s) + 2H+Cl-(aq) Pb2+(Cl-)2(aq) + H2(g)

(c) magnesium + Nitric acid Magnesium nitrate

+ hydrogen

Mg + 2HNO3 Mg(NO3)2 + H2

Mg(s) + 2H+NO3-(aq) Mg2+(NO3

-)2(aq) + H2(g)

(d) Calcium + Sulphuric acid

Calcium sulphate

+ hydrogen

Ca + H2SO4 CaSO4 + H2

Ca(s) + (H+)2SO42-

(aq) Ca2+SO42-

(aq) + H2(g)

(e) Zinc + Nitric acid Zinc (ii) nitrate

+ hydrogen

ZnZn(s)

++

2HNO3

2HNO3(aq)

Zn(NO3)2

Zn2+(NO3-)2(aq)

+ H2

+ H2(g)




N4/5 EXTRACTING METALS FROM ORES N4/5

1. Describe briefly the three methods that are used to extract metals from their ores.

2. Which metals occur naturally? Gold and silver.

3. Which metals are extracted using carbon? Zinc, iron, nickel, tin, lead and copper

4. Which metals have to be extracted by electrolysis of their molten ore? Lithium, potassium, calcium, sodium, magnesium and aluminium

5. Zinc is extracted from zinc(ii) oxide by heating with carbon. The ionic equation for this reaction is shown below.

zinc (ii) oxide + carbon zinc+ carbon dioxide Zn2+O2- (s) + C (s) 2Zn (s) + CO2 (g)

6. In question 5:

a) Which element is reduced? zinc (Zn2++ 2e’ Zn) as it has gained electrons

b) Which element is oxidised? Oxygen (O2- O2 +2e’) as it has lost electrons

7. Electrolysis is the decomposition of an electrolyte (a molten or aqueous compound that conducts electricity) using electricity. Complete the following table:

Electrolyte Product at anode(+)

Product at cathode(-)

Molten sodium chloride bubbles of chlorine sodiumAqueus sodium chloride bubbles of chlorine sodiumMolten aluminum oxide bubbles of oxygen aluminiumAqueous potassium bromide bubbles of bromine potassium

8. Look at this diagram for the electrolysis of aluminium oxide and answer the questions that follow:



a) What is the product at the anode? Bubbles of oxygen gas.

b) What is the product at the cathode? Molten Aluminium metal

c) The anode is made of carbon and burns away (needing to be constantly replaced). What is the product of this burning? Carbon dioxide

9. Here is a diagram to show the metallic structure of aluminium:

a) Define what a metallic bond is. Metallic bonding is the electrostatic attraction between the positively charged atomic nuclei of metal atoms and the delocalised electrons in the metal.

b) Explain in terms of structure and bonding why a metal like aluminium has:i) a high melting point - The electrostatic attraction between the positive ions and

the delocalised electrons acts in all 3-dimensions, strongly holding the lattice together. Most metals have high melting and boiling points.

ii) is relatively strong in tension - apply a force to (something) which tends to stretch it. The electrostatic attraction between the positive ions and the delocalised electrons acts in all 3-dimensions, strongly holding the lattice together. The metal ions can move position, as do the sea of electrons and so allows eventually for the metal to stretch.

iii) is a good conductor of electricity - Metals are good conductors of heat and electricity. This is due to the presence of the delocalised electrons.

iv) is malleable (easily shaped) - During reshaping the metal ions move position, as do the sea of electrons. The metallic bonding is not affected.

N4/5 PERCENTAGE COMPOSITION N4/5Find the percent compositions of all of the elements in the following compounds:

1) CuBr2Cu: 28.41%



Br: 71.59%

2) NaOHNa: 57.50%

O: 40%

H:2.50%

3) (NH4)2SN: 41.18%

H: 11.76%

S: 47.06%

4) N2S2N: 30.43%

S: 69.57%

5) KMnO4K: 24.68%

Mn: 34.81%

O: 24.68%

6) HClH: 2.74%

Cl: 97.26%

7) Mg(NO3)2Mg: 16.50%

N: 18.85% document.docx of 18 5-May-23


O: 64.65%

8) (NH4)3PO4N: 28.19%

H: 8.05%

O: 42.95%

P: 20.81%

9) Al2(SO4)3Al: 15.79%

S: 28.07%O: 56.14%

N5 OXIDATION & REDUCTION N5

1.



2.

(a) Ca(s) + Ni2+(aq) + 2 Cl-(aq)

Ca2+(aq) +2 Cl-(aq) + Ni(s)

Ca oxid Ni2+ red

(b) Cl2(g) + 2 K+(aq) + 2 Br-(aq)

2 K+(aq) +2 Cl-(aq) + Br2(l)

Cl2 red Br- oxid

(c) Zn(s) + 2 H+(aq) + SO4

2-(aq)Zn2+(aq) +SO4

2-(aq) + H2(g)

Zn oxid H+ red

(d) 4 Al(s) + 3 O2(g) 2 (Al3+)2(O2-)3(s)

Al oxid O2 red

(e) 3 Mg(s) + (Fe3+)2(O2-)3(s) 3 Mg2+O2-(s) + 2 Fe(l)

Mg oxid Fe3+ red

(f) The spectator ions are shaded.


(a) Cu2+ + 2e- Cu reduction

(b) Br2 + 2e- 2 Br- reduction

(c) Al Al3+ + 3e- oxidation

(d) Fe2+ Fe3+ + e- oxidation

(e) Cu2+ + e- Cu+ reduction

(f) 2 H2O + O2 + 4e-

4OH- reduction

(g) SO32- + H2O SO4

2- + 2H+

+2e-oxidation


N5 ELECTROCHEMICAL SERIES RULE 1 N5

1. potassium; sodium; magnesium; aluminium; iron; nickel; tin; lead; copper; gold.

2. (a)

(b) Copper and copper pairing would give a reading of 0 V.

(c) Platinum is poorer than gold at giving away electrons. If metal B was platinum:

(i) which metal from the metal A list would give the largest voltage? Answer calcium.

(ii) which metal from the metal A list would give the smallestvoltage? Answer gold.


voltmeter

METAL B

Filter paper soaked in salt solution.

METAL A

Order METAL A METAL B1 calcium silver

2 zinc tin

3 gold silver

4 nickel iron

5 copper copper


N4 ELECTROCHEMICAL SERIES RULE 2 DISPLACEMENT N4

1. Use the electrochemical series to predict if a displacement reaction will take place.

Metal Solution Displacement(yes / no) Products of Reaction

(a) zinc nickel(II) chloride yes zinc chloride + nickel

(b) calcium copper(II) sulfate yes calcium sulfate + copper

(c) zinc magnesium sulfate

no

(d) lead mercury(II) nitrate

yes lead(II) nitrate + mercury

(e) magnesium tin(II) chloride yes magnesium chloride + tin

(f) copper copper(II) iodide no

(g) gold silver nitrate no

(h) magnesium sulfuric acid yes magnesium sulfate + hydrogen

(i) aluminium hydrochloric acid yes aluminium chloride + hydrogen

gold nitric acid no



N4 ELECTROCHEMICAL SERIES RULE 2 DISPLACEMENT N4

2.

(a) zinc + nickel(II) chloride zinc chloride + nickelZn(s) + NiCl2(aq) ZnCl2(aq) + Ni(s)

(b) calcium + copper(II) sulfate calcium sulfate + copperCa(s) + CuSO4(aq) CaSO4(aq) + Cu(s)

(c) zinc + magnesium sulfate

No reaction, zinc cannot displace magnesium from a solution.

(d) lead + mercury(II) nitrate lead(II) nitrate + mercury

Pb(s) + Hg(NO3)2(aq) Pb(NO3)2(aq) + Hg(l)

(e) magnesium + tin(II) chloride magnesium chloride + tin

Mg(s) + SnCl2(aq) MgCl2(aq) + Sn(s)

(f) copper + copper(II) iodide No reaction, copper cannot displace itself from a solution.

(g) gold + silver nitrate No reaction, gold cannot displace silver from a solution.

(h) magnesium + sulfuric acid magnesium sulfate + hydrogen

Mg(s) + H2SO4(aq) MgSO4(aq) + H2(g)

(i) aluminium + hydrochloric acid aluminium chloride + hydrogen

Al(s) + 6 HCl(aq) 2 AlCl3(aq) + 3 H2(g)

(j) gold + nitric acid No reaction, gold cannot displace hydrogen from an acid.



N5 WRITING REDOX EQUATIONS N5

1. Zn(s) Zn2+(aq) + 2 e- Each reaction involves 2 electrons which cancel.Pb2+(aq) + 2 e- Pb(s)

Zn(s) + Pb2+(aq) Zn2+(aq) + Pb(s) REDOX

2. Fe(s) Fe2+(aq) + 2 e- Multiply the silver reaction by 2.Ag+(aq) + e- Ag(s)

Fe(s) Fe2+(aq) + 2 e- Each reaction involves 2 electrons which cancel.2 Ag+(aq) + 2 e- 2 Ag(s)

Fe(s) + 2 Ag+(aq) Fe2+(aq) + 2 Ag(s) REDOX

3. Li(s) Li+(aq) + e- Multiply the lithium reaction by 3.Al3+(aq) + 3 e- Al(s)

3 Li(s) 3 Li+(aq) + 3 e- Each reaction involves 3 electrons which cancel.Al3+(aq) + 3 e- Al(s)

3 Li(s) + Al3+(aq) 3 Li+(aq) + Al(s) REDOX

4. Al(s) Al3+(aq) + 3 e- Multiply the aluminium reaction by 2, the hydrogen by 3.

2H+(aq) + 2 e- H2(g)

2 Al(s) 2 Al3+(aq) + 6 e- Each reaction involves 6 electrons which cancel.6 H+(aq) + 6 e- 3 H2(g)

2 Al(s) + 6 H+(aq) 2 Al3+(aq) + 3 H2(g) REDOX




5. Mg(s) Mg2+(aq) + 2 e- Multiply the magnesium reaction by 3, the iron by 2.Fe3+(aq) + 3 e- Fe(s)

3 Mg(s) 3 Mg2+(aq) + 6 e- Each reaction involves 6 electrons which cancel.2 Fe3+(aq) + 6 e- 2 Fe(s)

3 Mg(s) + 2 Fe3+(aq) 3 Mg2+(aq) + 3 Mg2+(aq) REDOX

6. Cu(s) Cu2+(aq) + 2 e- Multiply the gold reaction by 2.Au+(aq) + e- Au(s)

Cu(s) Cu2+(aq) + 2 e- Each reaction involves 2 electrons which cancel.2 Au+(aq) + 2 e- Au(s)

Cu(s) + 2 Au+(aq) Cu2+(aq) + Au(s) REDOX

7. Na(s) Na+(aq) + e- Multiply the sodium reaction by 2.Br2(l) + 2 e- 2 Br-(aq)

2 Na(s) 2 Na+(aq) + 2 e- Each reaction involves 2 electrons which cancel.Br2(l) + 2 e- 2 Br-(aq)

2 Na(s) + Br2(l) 2 Na+(aq) + 2 Br-(aq) REDOX

8. Al(s) Al3+(aq) + 3 e- Multiply the aluminium reaction by 2, the iodine by 3.I2(s) + 2 e- 2 I-(aq)

2 Al(s) 2 Al3+(aq) + 6 e- Each reaction involves 6 electrons which cancel.3 I2(s) + 6 e- 6 I-(aq)

2 Al(s) + 3 I2(s) 2 Al3+(aq) + 6 I-(aq) REDOX

N5 WRITING REDOX EQUATIONS N5document.docx of 18 5-May-23


1.METAL A METAL B DIRECTION OF THE ELECTRON FLOW

lead aluminium From aluminium to lead

copper gold From copper to gold

nickel magnesium From magnesium to nickel

tin copper From tin to copper

silver lead From lead to silver

gold iron From iron to gold

calcium zinc From calcium to zinc

2.(a) Al(s) Al3+(aq) + 2e- Al is oxidised.

Pb2+(aq) + 2e- Pb(s) Pb2+ is reduced.

(b) Cu(s) Cu2+(aq) + 2e- Cu is oxidised.

Au+(aq) + e- Au(s) Au+ is reduced.

(c) Mg(s) Mg2+(aq) + 2e- Mg is oxidised.

Ni2+(aq) + 2e- Ni(s) Ni2+ is reduced.

(d) Sn(s) Sn2+(aq) + 2e- Sn is oxidised.

Cu2+(aq) + 2e- Cu(s) Cu2+ is reduced.

(e) On next page.




2.(e) Pb(s) Pb2+(aq) + 2e- Pb is oxidised.

Ag+(aq) + e- Ag(s) Ag+ is reduced.

(f) Fe(s) Fe2+(aq) + 2e- Fe is oxidised.

Au+(aq) + e- Au(s) Au+ is reduced.

(g) Ca(s) Ca2+(aq) + 2e- Ca is oxidised.

Zn2+(aq) + 2e- Zn(s) Zn2+ is reduced.


elements & symbols - whitburnscience web viewhard. 3. metal application is ... lead is resistant...

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