F.

3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )

Chapter 11 Reactivity of metals

Different reactivates of metals

 Some metal can react with cold water while some can only react with steam , from this , we can see that
Different metal have different reactivity

 This is called the Metal Reactivity Series

 What is reactivity ?
 Reactivity = Tendency to lose electrons

 To compare the reactivity of metals , we base on three factors:

 The lowest temperature at which the reactions starts
 A more reactive metal usually requires a lower temperature than a less reactive metal does

 The rate of the reaction

 Under the same conditions , a more reactive metal reacts faster than a less reactive one
 The amount of heat energy given out during reaction
 A more reactive metal gives out more heat during reaction

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 So , in this chapter , we are going to look at the reactions of metals with air , water and dilute acid to
help us arrange the metals reactivity !

Reaction of metals with air

( A ) Reactivity of metals with air
 Most metals , when they are heated in air , they will combine with in oxygen air to form metal oxides
 The questions would not be so strict forward , asking you what would happen when metal X
combines with oxygen in air
 So , what will they ask ?
 ONCE you see that the questions asking you what would happen when metal X burns in air , you
need to know that the equation is actually asking you what would happen when metal X combines
with oxygen in air
 when metal X burns in air = when metal X combines with oxygen in air

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )

What you need to remember ???

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
( C ) Appearance of metals and storage methods
 Usually Group I and Group II elements ( E.g. Potassium , Calcium , Sodium ) are very reactive , when
they are freshly cut , they look shiny .

 However , when they expose to air , the shiny surface of the metals become dull very soon as the
metal reacts with oxygen in air to form oxides on its surface , hence making the metal surface dull .

 The reactivity of metals : Group I > Group II > Group III

 To prevent reaction with air , very reactive metals ( e.g. potassium and sodium ) needs to be stored
under paraffin oil
 To prevent reaction with air , calcium ( which is quite reactive , but less reactive than potassium and
sodium ) is kept in an airtight container .

 For those not reactive metal , it does not need special method of storage . E.g. Gold . It always shows
attractive shiny colour .

 So , from the appearance and the method that used to store it , we can predict the reactivity of an
unfamiliar metal from its appearance .

Reaction of metals with water

 To test how metal reacts with water , we can first test with cold water . If there is no reaction , we then
use hot water or even steam .

( A ) Reaction of potassium with water

 When a small piece of potassium is added to water , it moves about vigorously on the water surface with
a hissing sound , then it melts to form a silvery ball , burns with a lilac flame , it becomes smaller and
smaller and finally all dissolves in water
 Potassium + water  Potassium hydroxide + hydrogen
 2K (s)  2H 2 O(l )  2KOH (aq)  H 2 ( g )

 The resulting potassium hydroxide is an alkaline solution , it will turn red litmus paper blue

( B ) Reaction of sodium with water

 As sodium and potassium are in the same group ( Group I ) , they will have similar chemical properties
 As they are in the same group , which means they have the same number of outermost shell electrons
 However , for group 1 , in chapter 6 ( The periodic table ) , we have learnt that when going down the
group , the reactivity increases
 Hence , the reactivity for potassium > sodium
 So , when sodium is added to cold water , the reactivity of it should be less vigorously when
compared with potassium

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 When a small piece of sodium is added to water , it moves about on the water surface with a hissing
sound , then it melts to form a silvery ball , burns with a golden yellow flame , it becomes smaller and
smaller and finally all dissolves in water
 Sodium + water  Sodium hydroxide + hydrogen
 2 Na(s)  2H 2 O(l )  2 NaOH (aq)  H 2 ( g )

 In normal case , it won’t burns to give a flame .

 Only when sodium ball happens to stick to the wall of the container
while moving around , it will burn with a golden yellow flame .

Observations of Group I elements with water

Element Observations
Lithium 1. Floats
2. producing hydrogen gas steadily
Sodium 1. Melts to form a silvery ball
2. moves about quickly on the water surface
3. Hissing sound
Potassium 1. Melts to a silvery ball
2. moves about very quickly on the water surface
3. Hissing sound
4. lilac flame
Rubidium Reacts even more vigorously than potassium does ( Caution : Explosive reaction ! )
Caesium Reacts even more vigorously than rubidium does ( Caution : Explosive reaction ! )

( C ) Reaction of calcium with water

 Unlike potassium and sodium , calcium is much denser than water , so when calcium drop into water , it
will sink to the bottom

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 When the reaction goes on , the size of calcium metal decrease gradually and finally disappear . Then , a
milky suspension is formed
 Why there is milky suspension ?
 As the white calcium hydroxide formed and it is only slightly soluble in water
Calcium + water  Calcium hydroxide + hydrogen
 Ca(s)  2H 2 O(l )  Ca(OH ) 2 (aq)  H 2 ( g )

 How to test the gas is hydrogen ?

 Test the gas with a burning splint
 If it burns with a “pop” sound , this shows that the gas is hydrogen

( D ) Reaction of magnesium
 Magnesium almost has no reaction with cold water

 It reacts slowly with hot water to give magnesium hydroxides and hydrogen
 Magnesium + Water  Magnesium hydroxides + Hydrogen
 However , magnesium hydroxides are only slightly soluble in water
 Hence , milky suspension is the formed !

 However , magnesium reacts vigorously with steam

 With strong heating , the water in the wet sand turns into steam . The steam then reacts with magnesium
to give an intense white light and a while solid , magnesium oxide .
 Magnesium + Steam  Magnesium Oxide + Hydrogen
 Mg (s)  H 2 O( g )  MgO(s)  H 2 ( g )

( E ) Reaction of aluminium
 Aluminium seem does not react with steam
 Because aluminium metal is usually covered with a very thin layer of aluminium oxide
 This oxide layer protects the metal from reaction

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 If the protective oxide layer is removed , the aluminium would react with steam to from aluminium
oxide and hydrogen
 How to remove this thin layer of aluminium oxide
 By sand paper !
 According to the metals reactivity Series :
 Reactivity of Aluminium : More reactive than zinc but less reactive than magnesium

( F ) Reaction of zinc and iron with steam

 Zinc and iron do not react with cold water or hot water , but it can react with steam as magnesium
does .
 Reactivity of Zinc : Less vigorous than magnesium
Zn(s)  H 2 O( g )  Z n O
( s)  H 2 ( g )

 Reactivity of Iron : Less vigorous than zinc , much less vigorous than magnesium
3Fe(s)  4H 2 O( g )  Fe3O4 (s)  4H 2 ( g )

( G ) Reaction of Lead , Copper , Mercury , Silver and Gold with steam

 No reaction with either cold water , hot water or steam ( even if you heated the metals strongly , there is
still no reaction ! )

Metal + Water  Metals hydroxide + Hydrogen

Metal + Water  Metals Oxide + Hydrogen

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )

Exercises
Rubidium ( Rb ) reacts with water to form hydrogen and a compound . Is this compound rubidium oxide or
rubidium hydroxide ? Why ?

rubidium is a
[ Solution ] Rubidium hydroxide ,
because

towards ater
metal
~

less reactive

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Reaction of metals with dilute acid
 The dilute acid that we are going to talk about is ONLY
 Dilute hydrochloric acid
 Dilute sulphuric acid
 BUT NOT Dilute nitric acid
 Why ?
 As it is an oxidizing agent
 The reaction of this acid with metal is totally different from the other two dilute acids , no
hydrogen gas is given out !

 Also , be careful that all these reactions regarding acid , the acid is dilute acid ( not concentrated acid )
 As if concentrated acid is used , the chemical reaction is totally different ! [ No hydrogen gas will
be given ! ]
 What would you see when metals add to the dilute hydrochloric acid or dilute sulphuric acid ( assume :
these two metals can react with these two acids ) ?
 When metal adds to the dilute acid , many colourless gas bubbles are given out
 The test tube quickly becomes warm
 So , this reaction is called exothermic reaction !

Metal + Dilute hydrochloric acid  Metals Chloride + Hydrogen

Metal + Dilute Sulphuric acid  Metals Sulphate + Hydrogen

 From the above equation , we can see that when metal reacts with dilute hydrochloric acid and dilute
sulphuric acid to give salt and hydrogen gas .

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 However , not all metals can react with dilute acid !
 Copper , Mercury , Silver and Gold will NOT react with dilute hydrochloric acid and dilute
sulphuric acid .
 Also , when lithium , potassium or sodium adds to the dilute acids , explosion would be occurred !

 The reactivity of metal in acid is following the metal reactivity series . When going down the metal
reactivity series , the reactivity decreases .

Exercises

( a ) Arrange the four metals in decreasing order of reactivity

( b ) Give possible names of the four metals

[ Solution ]

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Exercises
( A ) Multiple Choices
Q1. Which of the following metals can burn in air to give a dazzling white flame ?
A. Calcium
O B. Magnesium
C. Potassium
D. Silver

Q2. A metal that could be used conveniently in the preparation of hydrogen from dilute hydrochloric acid is
A. zinc
B. copper
O
C. lead
D. sodium

( B ) Structural Questions
Q1. Given the metals below :
TA. aluminium
B. iron
C. copper
D. gold
-

-
E. potassium

Choose the one that best fits the given statement in each of the following cases
As Pb
( a ) It is more reactive than silver but less reactive than lead C
( b ) It reacts violently with cold water E
( c ) It is not affected at all by air , water or dilute hydrochloric acid D
( d ) It reacts with steam to give a black product B
( e ) It shows the greatest tendency to lose electrons A

[ Solution ]

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )

Chapter 11 Reactivity of metals

Chemistry equations
( A ) Representing the reaction between magnesium and oxygen
 There are two ways to represent the reactions :
 Word equation
 Chemical equation

 We have learnt that when magnesium burns in air , magnesium oxides are formed . We can easily
represent it by word equation
Magnesium + Oxygen  Magnesium Oxides

 How can we represent it by chemical equation ?

 Remember that oxygen is a gas , the formula of it is O2 ( g )
 However , oxygen atom is only O
 They are different !

( B ) Equation as the summary of a reaction

 A chemical equation ( or an equation ) is just converting the word equation into chemical symbols
together with its physical states

 What are included in the chemical equation ?

 Reactants
 Products
 Physical states of the substances involved
 Relative number of particles ( atoms , molecules , ions or formula units )
 i.e. Balancing Equations !!!
 On each sides of the equations , there should be equal number of atoms / particles
( NEED TO BE FAIR !!!!!!!!! )

( C ) More about an equation

( I ) Balanced Equation
 What is balancing equation ?

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 An equation must be balanced in TWO things :
 Number of atoms
 The net ionic charges

 Be careful :
 We can ONLY balance the equations by adding numbers before the formulae of reactants and
products in the balanced equation ( you cannot change the formulae of the reactants and
products )

H 2 (g)+O2 (g)  H 2O2 (l )

 X X
H 2 (g)+O( g )  H 2O(l )
 These numbers are called stoichiometric coefficients
 In Chemistry , The coefficient “1” is usually omitted as all understand there is only one
molecule / atom / particle even if the number “1” is not written in the equation
 Only smallest possible whole numbers are used ( i.e. if all of the coefficients have common
factors , we can cancel it out ! )

Example
Q1. Express in words the information provided by the following equation
SO2 (g) + 2NaOH(aq)  Na 2SO3 (aq) + H2O(l)

Q2. Consider 2CO(g) + O2 (g)  2CO2 (g)

( a ) How many carbon atoms are on the
( i ) left – hand side of the arrow
( ii ) right – hand side of the arrow

( b ) How many oxygen atoms are on the

( i ) left – hand side of the arrow
( ii ) right – hand side of the arrow

( c ) Is it a balanced equation ?

Q3. State the number of atoms of each kind for the given number of formula units below :
( a ) Cl2O7
( b ) (NH4 )2Cr2O7
( c ) 3Fe2 (SO4 )3
( d ) 3Na 2CO3 10H2O

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Q4. Balance the following by adding suitable stoichiometric coefficients :
_ _ _ _ 3P b4 O 
(s) _ _ _ P b O 2( s ) + _ _ _ O ( g )

( D ) One – way reaction and reversible reaction

 The single arrow “ ” between the two sides of the equations indicates
 the reaction can go in one direction only !
 at the end of the reaction , all reactants react to form products

 The double arrow “ ” is also used sometimes , it indicates

 i.e. the reaction can go both forward ( left to right ) and backward ( right to left ) at the same time
 So , finally , both reactants and products are present

Steps for writing a chemical equation

 Step I : Write down a correct word equation

 Step II : Change the words in the word equation into chemical symbols

 Step III : Balance the chemical equation by counting the number of atoms on both sides of the
equations
 Make sure the total number of atoms ( i.e. H , O , N , S …. ) are fair on both sides

 Step IV : Write the state symbol after completing the balanced equations

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Metal Reactivity Series and the tendency of metals to form positive ions
( A ) Metals reacts by losing electrons
 Looking back the above reaction i.e. when magnesium reacts with oxygen to form magnesium oxides
2Mg(s)+O2 (g)  2MgO(s)

 Actually , after the reaction , magnesium metal changes to magnesium ions ( as MgO is an ionic
compound )
 Mg(s)  Mg 2+ (aq)
 However , this reaction is not completed as the charges on both sides are not the same
 We need to add electrons to balance the charge
 How ?
Mg(s)  Mg2+ (aq) +2e-

 So , magnesium is an electron donor ( After the reaction , magnesium give out its electrons )
 What about Oxygen atom ?
 After the reaction , oxygen gas changes to form oxide ions

 O2 (g)  2O2- (aq)

 However , this reaction is not completed as the charges on both sides are not the same
 We need to add electrons to balance the charge
 How ?

4e- +O2 (g)  2O2- (aq)

 So , oxygen is an electron acceptor ( oxygen accepts the electrons that donated by

magnesium to start the reaction )

 Overall Equation :

Mg(s)  Mg 2+ (aq) +2e- ....(1)

O 2 (g)+4e-  2O 2- (aq)...(2)

(1) x 2 2Mg(s)  2Mg 2+ (aq) +4e- ....(3)

(2)  (3)
2Mg(s)  2Mg 2+ (aq) +4e-
+) O 2 (g)+4e-  2O 2- (aq)
2Mg(s) + O 2 (g)  2O 2- (aq)  2Mg 2+ (aq)
2Mg(s) + O 2 (g)  2 MgO( s )

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )

 Be careful :
 Metals are always lose electrons to form cations , so metal is always +ve sign
 Non – metals are always gain electrons to form anions , so non – metal is always –ve sign

Example
Q1. ( a ) Write a chemical equation when iron is burnt in air
( b ) Which is the electron acceptor and which is the electron donor . Write an ionic half equation to
explain it briefly

Q2. ( a ) Write a chemical equation when iron is added to dilute hydrochloric acid
( b ) Which is the electron acceptor and which is the electron donor . Write an ionic half equation to
explain it briefly
[ Solution ]

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
( B ) Reactivity and readiness to lose electrons
 Reactivity = How readiness ( willingness / easiness ) for the metal to undergo the reaction
 The reactivity of the metal depends on how easily the metal atom loses it electrons
 And how easily the metal atom loses it electrons is according to the metal reactivity series ( if
the metals are present in the metal reactivity series ) .
 However , if the metals that you are interested are not in the metal reactivity series , we should
then look at the periodic table to find their reactivity !

 Down the group

 The reactivity of the metals increases
 As the readiness of losing the electrons increase
 Why ?
 This is because when going down the group , the size of the metal atom increases ( as the
number of the electron shell increases )
 The attraction force between the nucleus and the outermost electrons decreases
 The outermost shell electrons can lose very easily

 Across the period ( going from the left to the right ) :

 The reactivity of the metals decreases
 As the readiness of losing the electrons decrease
 Why ?
 This is because when moving across the period , the number of protons of the metal atom
increases
 The attraction force between the nucleus and the outermost electrons increase
 The outermost shell electrons can NOT lose very easily !
 Hence , the reactivity of the metals decrease

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Displacement reactions of metals in aqueous solution
 A metal higher in the metal reactivity series will displace any metal lower in the series from the solution
that containing this metal ions .
 A metal higher in the metal reactivity series is more reactive , so its atoms lose electrons more
readily to form cations .
 Then , the cations of the less reactive metal would accept these electrons , forming back the atoms
of the less reactive metal

( A ) Copper in silver nitrate solution

Cu(s)  2 AgNO3 (aq)  Cu( NO3 ) 2 (aq)  2 Ag (s)

 From the metal reactivity series , copper is higher than silver

 So , copper can displace the silver metal from the silver nitrate solution

( B ) Iron in Copper ( II ) sulphate solution

Fe(s)  CuSO4 (aq)  FeSO4 (aq)  Cu(s)

 From the metal reactivity series , iron is higher than copper

 So , iron can displace the copper metal from the copper ( II ) sulphate solution

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
( C ) Copper in Iron ( II ) sulphate solution

 From the metal reactivity series , iron is higher than copper

 So , copper can NOT displace the iron metal from the iron ( II ) sulphate solution

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Example
Predict , with reasoning , whether a reaction takes place in each of the following :
( a ) Zinc is added to magnesium chloride solution
( b ) Magnesium is added to lead ( II ) nitrate solution
( c ) Silver is added to dilute sulphuric acid
( d ) State what type of reaction ( if any ) takes place and write an appropriate equation for the reaction

[ Solution ]

Ionic equations
 To represent chemical reactions , we can not only use word equations and chemical equations , but also
we can use ionic equations
 Are all the chemical reactions be represented by ionic equations ?
 NO !!!
 Example : CaCO3 (s) + H2SO4 (aq)  CaSO4 (s) + CO2 (g) + H2O(l)

 What is an ionic equation ?

 An ionic equation is an equation involving ions in aqueous solution . Only those ions formed or
changed during the reaction are included

 How to write an ionic equation ?

 Write a full chemical equation first
 Only change those substance with (aq) state into one +ve and one –ve ions
 The other substances with ( s ) , ( l ) or ( g ) state remind unchanged !
 Cancel out the same ions on both sides
 Check carefully that the charges on both sides are the same
 Be careful : 2HCl(aq)  2H+ (aq) + 2Cl- (aq)

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Example
Q1. Cu(s) + 2AgNO3 (aq)  Cu(NO3 )2 (aq) + 2Ag(s)

[ Solution ]

Cu(s) + 2AgNO3 (aq)  Cu(NO 3) (aq)

2 + 2Ag(s)
Cu(s) + 2Ag  (aq)  2NO3 (aq)  Cu 2 (aq) + 2NO3 (aq)  2Ag(s)
Cu(s) + 2Ag  (aq)  Cu 2 (aq)  2Ag(s)

Q2. 2NaHCO3 (aq) + H2SO4 (aq)  Na 2SO4 (aq) + 2CO2 (g) + 2H2O(l)

[ Solution ]
2NaHCO3 (aq) + H 2SO 4 (aq)  Na 2SO 4 (aq) + 2CO 2 (g) + 2H 2O(l)
2Na + (aq) + 2HCO3- (aq) + 2H + (aq) +SO 4 2 (aq)  2Na + (aq) +SO4 2 (aq)+ 2CO2 (g) + 2H 2O(l)
2HCO3- (aq) +2H + (aq)  2CO 2 (g) + 2H 2O(l)

Example
Q1. Write the ionic equation for the following reactants
( a ) Pb(s)+CuSO4 (aq)  PbSO4 (aq) +Cu(s)
( b ) Zn(s)+2AgNO3 (aq)  Zn(NO3 )2 (aq) +2Ag(s)
( c ) Mg(s)+2AgNO3 (aq)  Mg(NO3 )2 (aq) +2Ag(s)
( d ) 3Mg(s)+2Al(NO3 )3 (aq)  3Mg(NO3 )2 (aq) +2Al(s)

Q2. Find the values of y and z in the ionic equation

y C2l ( g ) + 6- O H( a q ) - z C l 3 (- a q ) + C2 l O ( a q ) + 3 H O ( l )

[ Solution ]

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Extraction of metals from their ores
 Extraction = Process of getting a metal from its ore

 Why do we need to extract the metal ?

 Usually , the metals that we get on earth are not pure , those metals in their ores are usually
combined with other things ( e.g. oxygen )
 If we want to get back the pure metal , we need to extract the metal out from its ores

 We need to extract this metal from its ores before we can use the metals
 Metals play an important role in our daily lives .
 For example , we use metals to make ships , metal cutlery to eat food , cars …

 However , most of the metals are not exist as free elements in the Earth .
 Only some of the unreactive metals e.g. gold , silver … exists as free elements in Earth
 Most of the metals exist as compounds in nature

 There are lots of methods to extract the metals from its ores

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
 What kinds of factors affecting us to choose what kinds of methods to extract the metals ?
 The reactivity of the metals
 The method used to extract a metal from its ore depends on the position of the metal in
the metal reactivity series

 Why gold and silver will be discovered so earlier ?

 As they are very unreactive
 They don’t like to react with many things including oxygen
 Why ?
 As they are so stable , even we force this unreactive metal to form compounds , the
compounds are also unstable
 These unstable compounds will also decompose very quickly to form the unreactive metal
back
 On the contrary , those reactive metals would like to form compounds very readily
 The compounds that these reactive metals formed are very stable , which means that the
reactive metals are unstable !
 So , they exists as free elemenets on earth
 People just dig it from the ground and use some simple methods to take the metals out !

 The easiness of the metals to be discovered are also affected by the metal reactivity series !
 The lower the position of a metal in the metal reactivity series , the earlier it was first discovered

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Exercises
Some information about the extraction methods of five different metals A , B , C , D and E are listed as
follows :

Arrange the positions of metals in the metal reactivity series based on the above information , from the
lowest to the highest . Explain your answer

[ Solution ]
Mechanical separation is the easiest way to extract a metal from its ores . Thus , metal A must be the least
reactive ( i.e. the lowest in the metal reactivity series )

Metal D should be in a positive higher than that of A , but lower than that of E as it can be displaced out
from its solution by E

Metal C should be in the highest position among the five metals since it is the most difficult to be extracted

Metal B should be in a position higher than that of E since it is extracted by carbon reduction

So , the positions of five metals in the metal reactivity series should be :

A< D < E < B< C

Example
Q1. ( a ) Is it possible to reduce haematite ( containing iron ( III ) oxide ) by heating it with magnesium ?
Why ?
( b ) Is this method used in industry to extract iron form haematite ? why ?

Q2. Write balanced chemical equations for the following reactions :

( a ) Iron ( III ) oxides + carbon  iron + carbon dioxide
( b ) silver oxide  silver + oxygen

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
[ Solution ]

Exercises
( A ) Multiple Choices
Q1. Which of the following metals can burn in air to give a dazzling white flame ?
A. Calcium
B. Magnesium
C. Potassium
D. Silver

Q2. A metal that could be used conveniently in the preparation of hydrogen from dilute hydrochloric acid is
A. Zinc
B. Copper
C. Lead
D. Sodium

Q3. Which of the following is / are related to the metal reactivity series ?
( 1 ) methods of storage of metals
( 2 ) percentage abundance of the metals in the Earth’s crust
( 3 ) Densities of the metals
( 4 ) thermal stability of metal compounds

A. ( 1 ) only
B. ( 1 ) and ( 4 ) only
C. ( 2 ) and ( 3 ) only
D. ( 2 ) , ( 3 ) and ( 4 ) only

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Q4. The action of dilute nitric acid on copper is represented by the following equation :
vCu(s)+wHNO3 (aq)  xCu(NO3 )2 (aq)+yH2O(l)+zNO(g)

The values of v , w , x , y and z in the balanced equation are respectively

A. 1 , 4 , 1 , 2 , and 2
B. 3 , 4 , 3 , 2 and 2
C. 3, 8 , 3 , 4 , and 2
D. 1 , 3 , 1 , 2 , and 1

Q5. An iron nail is placed in each of the following test tubes

Which of the following about the experiment is / are correct ?

( 1 ) Blue colour becomes deeper in test tube 1
( 2 ) Some shiny cyrstals are observed in test tube II
( 3 ) No change is observed in test tubes III

A. ( 1 ) only
B. ( 2 ) only
C. ( 1 ) and ( 2 ) only
D. ( 2 ) and ( 3 ) only

Q6. Which of the following mixtures is likely to react to form new substances when being heated strongly ?
A. Copper and lead ( II ) oxide
B. Copper and magnesium oxide
C. Zinc and copper ( II ) oxide
D. Iron and magnesium oxide

Q7. Which of the following metals will NOT displace silver from aqueous silver nitrate solution
A. Copper
B. Iron
C. Silver
D. Zinc

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Q8. In which one of the following sets are ALL metals extracted by electrolysis ?
A. K , Na , Hg
B. Mg , Cu , Fe
C. Ca , Ag , Al
D. Al , Ca , Mg

( B ) Structural Questions
Q1. Given the metals below :
A. Aluminium
B. Iron
C. Copper
D. Gold
E. Potassium

( a ) It is more reactive than silver but less reactive than lead

( b ) It reacts violently with cold water
( c ) it is not affected at all by air , water or dilute hydrochloric acid
( d ) It reacts with steam to give a black product
( e ) It shows the greatest tendency to lose electrons

Q2. Balance the following equation :

( a ) Al(s) + O2 (g)  Al2O3 (s)
( b ) C2 H6 (g)+ O2 (g)  CO2 (g) + H2O(l)
( c ) Cu(NO3 )2 (s)  CuO(s) + NO2 (g) + O2 (g)
(d) KClO3 (s)  KCl(s) + O2 (g)
( e ) C2 H2 (g)+ O2 (g)  CO2 (g) + H2O(l)
( f ) CuO(s)+ NH3 (g)  Cu(s) + H2O(l) + N2 ( g )
( g ) FeS2 (s)+ O2 (g)  Fe2O3 (s) + SO2 ( g )
( h ) O2 (g)+ NH3 (g)  NO(g) + H2O(l)
( i ) Mg3 N2 (g)+ H2O(l)  MgO(s) + NH3 (g)
(j) Al(s) + Fe2+ (aq)  Al3+ (aq) + Fe(s)

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Q3. Predict whether a reaction takes place in each of the following experiments . If there is a reaction , state
all observable change(s) and write the chemical equation for the reaction
( a ) a piece of magnesium is added to dilute sulphuric acid
( b ) a piece of calcium is heated strongly in air
( c ) a piece of gold is heated directly
( d ) calcium oxide powder is heated directly
( e ) an iron nail is added to zinc sulphate solution
( f ) a piece of copper wire is added to silver nitrate solution

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )
Q4.

( a ) What is the colourless gas formed when the oxide of metal A is heated directly ?
( b ) Give ONE possible name of metal A
( c ) What is the colourelss gas formed when metal B reacts with cold water ?
( d ) Give ONE possible name of metal B
( e ) Suppose metal C is zinc
( i ) Write a chemical equation for its reaction with dilute hydrochloric acid
( ii ) Write an ionic equation for its reaction with copper ( II ) sulphate solution
( f ) Arrange the three metals A , B and C in order of increasing reactivity

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F.3 Chemistry 2021-2022 Chapter 11 Reactivity of metals ( Prepared by Janet Ho )

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