Activity Series
To becnme familiar with the relative activities of metals in chemical reactions.
Apparatus
small test tubes' (13)
test tube rack
OBTECTTVE
APPARATUS
AND CHEMICALS
Chemicals
0.2 34 Ca(NO3)2
0J M Zn(NOt)2
0.2 M FeSO3
02UCuSO#
7 small pieoes each of calcium,
magnesium, zinc, iron wool,
tin, and copper
0.2 M Mg(NO )2
0.2 M Fi(NOT)
6 HHCl
Chemical elements are equally classified by their properties into three groups:
metals, nonmetals, and rnetalloids. Most of the known elements are metals.
Their physical pmperties include high thermal and electrical conductivity, high
luster, mallenbility (ability to be pounded flat without shattering), and ductility
(ability to be drawn out into a fine wire). All common metals are solids at room
temperatum except mercoty, which ie a liquid The periodic table illustrated ie
Figure 15.1 ahows die three cla9Sificotions of the elements.
All elements to the left of the shaded area except hydrogen are metals.
Those to the right are n umetsls. Those in the shaded area have intermediate
pmpei4ies and are called semimetals or inetalloids. Families or greups of elements coneiei of elements in vertical columns in the periodic table. £lleoiena
within a gmup ot family (called congeners) have similar chemical properties
because they have similar valence electroiiic structures; thai is, the number of
valence electrons (electrons in the outermost shell) is the same for all
members of a family or group. For historical reasons, most of the groups
lieve names, some often referred to by their names. These are the following:
1. Group lA, called iiJ&fi metals becaiase they react with oxygen to ffiroi bases
2. Group 2A, called ‹ztR/iw
weiab because their presence makes soils
3. Group 3A, no coiljniori name
4. Group 4A, no common name
’A apot plaie msy be use4 in plc ottast tche.
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2012 Pearson EdW8tion, fnc.
DISCUSSION
Periodic Table of the Elements
5. Cironp SA, called pnicticles, L:om the Greek word meaning choking suffocation
6. Group 6A, called chalcogeiis, Tom Greek roots meaning ore former
7. Jkiroup 7A, called halogens, from Greek roots meaning salt former
8. / Ciroup 8A, called rare, noble, or irterf gaces because they are tare and
were thought to be unreactive
Those most flequenily referred to by group name are the alknli metal2, the
alkaline eortli metals, the halogens, and the rare gases.
The three brond categories of the elements also have somewhat similar
chemical properties. For example, metals, as compared with the other elements,
have relatively low ionizntion potentials and enter into chemical combination
with nonmetals by fp iitg electrons to become cations. This can be symbolized
by the following equation:
M —-r 1vI“+ + ne*
Nonnietals, as compared with itletals, have relatively high electron affinities
and enter inio chemical combination with metols by gaining electrons to
become onlons. This can be s bolized by the following equation:
X + ne‘
X“°
Specific examples of these types or reactions can be divided into several useful
categories, z'!iich the following exan ¡rles illustrate.
Electron-Transfer Reactions
1 REACTIOJNS WITH OXYGEN
2Mg(s)+ Ozla)
2MgO(s)
In this reaction, magnesium is oxidized by oxygen, which is reduced by magnesium (c”Section 4.4). This can be better illustrated by breaking down the
reaction into the folloz4ng fictitious although helpful steps:
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2(Mg —+ Mg+ + 2e*)
oxidation
O2 -f 4e" —r
reduction
20**
2Mg + 02 —r 2MgO
oxidation-reduction (redox) reaction
In oxidation, the oxidized element loses electrons and becomes more positive.
In reduction, the reduced element gains electrons end becomes more negative.
Oxidation is always associated with a concomitant reduction and in a balanced
reaction the number of electrons lost equals the iimnbcr of electrons gained.
2 REACTIONS WITH WATER
2Na(s)+ 2H2O(/)—-r 2N8OH(42Q) •b Hz(8)
Cars) 2H2O(1) —r
Ca(OH)2(eg)+ H2(g)
The ioziic equations for diese reactions fetter illustrate the election-transfer press.
2Na(s)+ 2HtO(5 —+ 2Na“(aq) + 2OH*( ) +
2$&)
2
Ca(i) + 2H O(I) —+ Ca (aq) + 2OH‘(nd) + H2(g)
3 REACTIONS WITH ACIDS
Zn(i) + 2HCl(o9) —+ ZnCl2(aq) + Ht(g)
or
Zn(x) + 2H°(eg) + Cl*(‹iq)
Zn"(oq)+ 2Cl*(aq) + H2(g)
Because the chloride ion is merely a spectator—that is, it ‹lees not participate'in
the reaction-it may be omitted, yielding the net ionic equmion (HSection 4.4).
Zn(s j+ 2H*(aq) —r
Znz*(eg) + H (g)
or simply
Zn + 2H* —r
Zn2++ H2
4 ELECTRON TRANSFER AMONG METALS
or
z»( ) + c«2•(«q)—+ Zn2+( )+ Cu(s)
or simply
zi +cq24
+ +Cu
Note once again that in the ionic equation, the spectator ion (hiO3 ) has bean
omitted because it takes no active part in the reaction and serves only lo provide
electrical neutrality («?'Section 4.4). Therefore, any other soluble salt ofoopper(II),
such as chloride, sulfate, or acetate, could perfomi the sairie function.
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lu this game of “musical electmns,” there ate only cnough electmns for
nnc iit‹›n› ‹›f' the eysccm. Tu aohiovc tho Inwcst cnvrgy Icvcl km thv .•ystam.
the m‹›re activo mclal ol” s pair will lusc ulcctruns to tho mora }xsssive motal
or will ceact snore vigorously with wctor, acids, or oxygci\. In somo cagos, no
reaction will occur. Wichout prinr knowledge, you havc no wey la predict
these events.
PROCEDUI€E
A. Reactions of Metall with Acid
To each of six test tubes containing 0.5 md of dilute 6 HCI, add a smnll
piece of the metals Ca, Cu, Fc, Mg, So. and Zn. Obser 'c the wst mbas aad
nole any changes tbot occur (such as whether a gas is cvolved, whether the
gas is vigomus and what cc)nr changes occurred). Enter yuur observations ‹›n
thc mpcn short and write b‹›th complete and ic›nic cctuotiun9 Fc›r cacb reaction
noted. After cumplcling cach series c›f i<actiooe, dispose c›f Lhc contents of”
your iest tuhcs in the designated containers.
B. Reactions of Metall with Solutions of Metsl lons
(WORK IN PAIRS FOR THIS STEP.) Add a small piece of calcium metal
to each of seven test tubes containing about 0.5 ml. of Ca(NO3)2,
CuSO#, FeSO#, fe(NOj)j, Mg(NOi)2, SnCl , and Zn(NO )j soluéotis. Note aiiy
rTaction that occurs by observing whether a color change occurs on the surface of
the metal or in the so1uti‹m or ivbetsher gas is evolved. Pay close attention io
whetber tiie Co dimilvei (becaum there may he other sidt reecti•ns). Reccrd your
oJ;iservetions on the rcjx›rt shect Writc both ciznpletc and i‹mic equtfiwis ft›r any
reac*on ßiat ‹x:cx After compJctinp each stilles ‹›f reactions, disjx›sc of the
contents of your test tubcs in the dcsignafed ccntninetä.
Repeat the preceding process by adding a small piece of copper to der
0.5 mL of each of the metal-cation solutions. Oo the same for iron, magpesiuin.
tin, atid zinc and record your observations. Pay close attention to wliether the
metal dissolves. Write toth complete molecular and ionic equations for all
C'. Relative-AcH1/ Sertes
Lrom tbe inIormali‹›n in the tahle yuu constructed In Part J3, you can rank
thmc six mclaJn occc›rding to their mlativ¢ cbemioal reactivities. One nd the
metals will replace all others in solution. for example, it‘ calcium metal is
oxidized by solutioris containing cations of each of the otntc metals, tt is
most reactive. One of the other metals that wilt replace all but calcium is the
ntxt most reactive. Finally. one of the metnls will not replant eny of the other
mTtal cationc from solution. Therefore, it is least reactive. List the metals on
your report sheet in terms of decreasing reactivity starting with the most
reactive (1} and ending with the least reactive (6).
GIVE IT GOME THOUGHT
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Activity Series
Pre-tab
Questions
Before beginnlag lbws experiment In tbe laboratory, you sbould be sb)e to snswer the
fol)owtng questions.
1.
What distinguishes a metal from a nonmetal†
2.
What does ionlzation potential measure†
3.
What does electron a{finity measure?
4. Why must oxidation be accompanied by a reductions
5. How do you determine the relative reactivities of metals?
6. Complete and balance the following:
(I) ’1-Oz (81
Zn(s) + HCI(
)
—i
Zn(s) +Cu2 (aq) —r
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7.
Balance the following reactions and identify the species that have been oxidized and the species that
have been reduced.
Species oxidized
Reaction
8.
C12(g)+ I*{aq)
I,{s) + Cl*‹aq)
WO 2 (s)+ H2(g1
W(s) + H;O(f)
Ca(s) + H2O(I) —+
H2 (g) + Ca(OH)j{s)
Al(s) •l• O2p (Q)
A zO3 s)
Species reduced
Assuming that the following redox reactions are foiuid to occur spontaneously, identify the more active
metal in each reaction.
More actlve metal
Reactlon
2Li(s)+ Cu *(rig) —r
2Li*(‹aq) + Cu(s)
Cr(s) + 3V'“(
3V'*(eg) + C/°(«q)
)
Cd(i) + 2Ti “(eg) —+ 2Ti2+[aq j+ Cd‘"(sq)
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Desk
Name
De
Laboratory liistructor
REPORT SHEET
Actšvity Series
A. Reactlons of Metals with Aeid
Metal
Reactlon
wlth HCl
Observatlon
EqucQoas
Gas evolved; solution
turned blue
Co(s)+ 2HCI(aq) —+ CoCly(aq)+H2(g)
Cu
Fe
Sn
Example:
Co
Yes, slowly
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Co(s)+2H*(aq) —+ Co2°(aq)+H2(s)
B
. Reactions of Mlei!a s with Solut:
Yes, turns
aluminum dark
N.R. means that no reaction occg¡red.
Example:
L“.un›plet.e eqii Ifinn
Ca(s)+ Mg(NOM )2(aq)
Ca(s) + Zn(NOM )2(aq)
Ca(s)+ Fe(NO3 $(aq)
3Ca(s) + 2Fe(NO3)3(aq) —+
2Ca(s)+SnC!4(•q› —•
Ca(s) +CuSO4(aq) —•
Mg(s) + Zn(NO3 )2(aq) —+
Mg(s)+ Fe(NO3 (aq)
3Mg(s)+ 2Fe(NOM (aq)
2Mg(s)+SnCIy(aq) —+
Mg(s) i CuSOy(aq)
Zn(s)+Fe(NO3h(••i) —*
3Zn(s) 2Fe(NO3 $(aq) —+
2Zn(s)+ SnCI,(aq) —+
Zn(s)+ CuSO (aq)
2Fe(s) SnCIt(aq)
Fe(s)+ CuSO4(aq)
Sn(s) + CuSO4(aq)
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apel ionic equatioti
C. Relative-Activity Series
Least reactive
Most reactive
1.
3.
2.
4.
6.
5..
QUESTIONS
1. Which of these six metals should be most reactive toward oxygen†
2. Which of the oxides would you expect to be themially unstable and decompose according to the
equation†
2MO
2M + 02
3. Sodium is slightly less reactive than calcium. Predict the outcome of the following reactions:
Na+H2O—+
Na+Ops
N»+HC1 —+
Na + Ca2° —+
4. Which is more reactive Fe°° or Fe3 ? why7
5. From the dsta in Table B, rank the activity of aluminum.
6. For each of the following reactions, indicate which substance is oxidized and which is reduced. Which
substance is the oxidizing agent, and which is the reducing agent?
Subsmnce
oxidised
2A1(5) + C z181
2AlCl3(I)
8H"(o9) + MnO4 (oq}+ 5Fe2 (oq) —r
5Fe“(o9) + Mn2’ (
) + 4H2Otf)
FeS(s) +3NO “(og)+41-I*(og) —+
3Nt3(g) + SOA 2 (o9) + Fe'“ (aq) + 2H2O(i)
Zn(sl + 2HCl(aq) —-+ ZnCl (aq)+ 2H2(g)
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Substance
reduced
Oxidizing
agent
Reducing
agent