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Activity Series

posted Jun 7, 2016, 1:22 PM by Upali Salpadoru   [ updated Jun 14, 2016, 10:59 PM ]

A series.jpg


Fig.1 Some metals give off Hydrogen rapidly.


Reactivity of metals vary widely. If we know the order of reactivity it would be easy to predict chemical reactions. It would be also become easier to remember their properties.

Here is the generally accepted Activity series of metals which also include Carbon and Hydrogen for comparison.

 

 Li  KCa  Na Mg Al C ZnCr Fe  Cd Co Metal
 5204195904967375781086506653763868760Ionization energy

  


 Ni SnPb  HAs  Cu HgAg Pt Au Metal
73770971613129477461007731870890Ionization energy


First let us break this up into groups and learn some common behavior.

METAL

GROUPS

 

 

                    REACTIONS

 

In air

 With Water

Li,K, Ca,Na

 

Tarnishes in air.

(stored in Kerosene oil)

Metal + Oxygen

give

                metal oxide.

Vigorously react  in cold.

M + water

Give

  M hydroxide + Hydrogen

Mg,Al, Zn

 

Burns in air

React with steam

M + Water

Give

Mhydroxide + H2

Cr,Fe, Cd,Co, Ni

 

Combine with oxygen slowly

Rea→→→ct with steam.

Sn,Pb,H2,As

 

Combine with oxygen.

No

No Reaction

Cu,Hg,

 

Combine with oxygen when heated.

Ag Pt,Au

 

 

Did you ever wonder , why certain metals are so active while some are very passive. 

The activity of an element depends on several factors.

Size of the atom.

  • Number of protons and how the electrons are distributed.
  • The nature of the reactants
  • and The environmental conditions are mainly responsible.
    

We have an idea of the activity series but according to Lord Rutherford it not science unless we have a way to introduce it in numbers. So is there a way to do that?

There are two factors that can measure according to the accepted units.

They are:-

1.  The electrode potential.      2.  Ionization energy.


Most metals can lend electrons(Oxidation) to non metals like Oxygen and chlorine.

Sodium atom - electron =  sodium ion.

Na - e = Na+

The energy required for this is called ionization energy. 

If the ionization energy is low , it would be easier to donate an electron.

This is not the only factor that governs the activeness.  For exxample the ability of the other partner to accept electrons is also important.


Reaction with dil. acids and electrode potentials.


Name

E° (volts)

Reactions with dil. Hydrochloric acid.

Reaction with dil. Sulphuric acid.

Li

Lithium

-3.03


             DANGER

    

             DANGER

K     

Potassium

-2.92

Never Try


Sr

Strontium.



Never Try

Ca   

Calcium

-2.87



Na

Sodium

-2.71



Mg  

Magnesium.

-2.37

Mg(s) +2 HCl(aq) → MgCl2(aq)+H 2


Mg(s) + 2H2O(g) → Mg(OH)2(aq)+H2

Al  

Aluminium

-1.66

2Al   +6 HCl →2  AlCl3 +3 H2

Very slow start due to an oxide layer.

2Al + 3H2SO4 → Al2(SO4)3 + 3H2

Carbon


No reaction

No reaction

Zn  

Zinc

-0.76

Zn(s) + 2HCl → ZnCl2 + H2

Zn + H2SO4 → ZnSO4 + H2

Cr

Chromium


Cr(s) + 2HCl(aq) → CrCl2(aq + H2

Pure metal resists

Cr2 + H2SO4 → CrSO4 + H2

Fe

Irion

0.44

Fe(s) + 2HCl →FeCl2 + H2

2Fe(s) +  H2SO4 → Fe2SO4 + H2

Cd

Cadmium


Cd (s)+ 2 HCl (aq)→ CdCl2 (s) + H2

Very slow

Cd + H2SO4 → CdSO4 + H2


Co

Cobalt


Co + 2HCl → CoCl2 + H2↑;  

Co + H2SO4 → CoSO4 + H2

Ni

Nickel


Ni + 2HCl → NiCl2 + H2↑

 Ni + H2SO4 → NiSO4 + H2↑.

Sn

Tin


Sn + HCl → SnCl2 + H2

Sn +H2SO4 → SnSO4 + H2

Pb  

Lead

-0.13

Pb(s) +2HCl → PbCl2 + H2

Very slow.

No reaction

H2

Hydrogen

0.0

2 H2(g) + No reactionO2(g) →  2H2O(l)


As

Arsenic



4As(s) + 3O2(g) → As4O6(s


Cu

Copper

+ 0.34



Hg

Mercury


2Hg + O2 =  2HgO  

(reversible)


Ag

Silver

+0.80

2 Ag + S →  Ag2S

2 Ag2 O  →   4Ag + O2


Pt

Platinum


Pt(s) + 3F2(g) → PtF6(s) [dark red]


Au

Gold

+1.50

2Au(s) + 3Cl2(g) →2AuCl3(s)

Forms amalgam with Hg and dissolves in aqua regia


Electrochemical Series


 Li KCa  Na Mg Al C ZnCr Fe  Cd Co Metal
 -3.03 -2.92 -2.87 -2.71 -2.37 -1.66 +0.21 -0.76  -0.44   Electrodde potential

  


Co Ni SnPb  HAs  Cu HgAg Pt Au Metal
+1.2
Co3+
 -0.05 +2.0+1.8 0.0 -0.2 +0.15
Cu2+
 +0.85 +0.8 + 1.2 +1.5Electrode potential





Out of all the elements in the Earth almost 80% are metals. Even hydrogen which we normally consider as a non - metal due to its gaseous state is predicted to behave as a metal if frozen to solid  state. Metals have a number of common properties but they become very interesting  due to their subtle variations.

Remembering the properties of nearly 100 metals is no easy task. This arrangement of metals, ,'Activity Series', according to the ascending order of reactivity,  is a boon to students as well as to Industrial chemists.

Any scholar will get enthralled by the beauty of patterns emerging not only from chemical properties but also from completely unconnected factors such as age of discovery and demand. We table here a few of those.


Activity Series and the Discovery of Metals.

Discovery.jpg

Activity series and the cost of metals

Metals.jpg




Name

Density

g/cm3

Reactions with air

Reaction with Water

Li

Lithium

0.5

4Li(s) + O2(g) → 2Li2O(s)

6Li(s) + N2(g) → Li3N(s


2Li(s) + 2H2O → 2LiOH(aq) + H2(g)

K     

0.9

K(s) + O2(g) → KO2(s)

K2O also possible

2K(s) + 2H2O → 2KOH(aq) + H2(g)

Sr

Strontium.

2.6

2Sr(s) + O2(g) → 2SrO(s)

3Sr(s) + N2(g) → Sr3N2(s)


Ca   

Calcium

1.6

2Ca(s) + O2(g) → 2CaO(s)

3Ca(s) + N2(g) → Ca3N2(s)

Ca(s) + 2H2O(g) → Ca(OH)2(aq) + H2(g)

Na

Sodium

0.97

4Na s + O2  g → 2Na2O s

2Na(s) + 2H2O → 2NaOH(aq) + H2(g)

Mg  

Magnesium.

1.74

2Mg(s) + O2(g) → 2MgO(s)

3Mg(s) + N2(g) → Mg3N2(s)

Mg(s) + 2H2O(g) → Mg(OH)2(aq)+H2(g)

Al  

Aluminium

2.7

4Al(s) + 3O2(l) → 2Al2O3(s

 Very slow reaction

Carbon

Zn  

Zinc

7.1

2Zn(s) + O2(g) → 2ZnO(s)


Cr

7.2

2Cr(s) + 3Cl2(g) → 2CrCl3(s)


Fe

Irion

7.9

4Fe(s) + 3O2(g) → 2Fe2O3(s)

2Fe(s) +  3H2O(g)      Fe2O3(s) +3H2(g)

Cd

Cadmium

8.7

2Cd(s) + O2(g) → 2CdO(s)

No reaction

Co

Cobalt

8.9

2Co(s) + O2(g) → 2CoO(s)


Ni

Nickel

6.9

2Ni(s) + O2(g) → 2NiO(s)


Sn

Tin

7.3

Sn(s) + O2(g) → SnO2(s)


Pb  

Lead

11.3

2 Pb(s) +O2  (g)→  2PbO(s)


H2

Hydrogen

0.09

g/L

2 H2(g) + O2(g) →  2H2O(l)


Ar

Assenic

5.8

4As(s) + 3O2(g) → As4O6(s


Hg

Mercury

13.5

2Hg + O2 =  2HgO  

(reversible)


Ag

Silver

10.5

2 Ag + S →  Ag2S

2 Ag2 O  →   4Ag + O2


Pt

Platinum

21.5

Pt(s) + 3F2(g) → PtF6(s) [dark red]


Au

Gold

19.3

2Au(s) + 3Cl2(g) →2AuCl3(s)

Forms amalgam with Hg and dissolves in aqua regia



Activity series and Ionization energy.

110





















100





















90





















80





















70





















60





















50





















40





















30

x10

Li

52

K

42

Ca

59

Na

50

Mg

74

Al

58

Zn

51

Cr

65

Fe

76

Cd

87

Co

76

Ni

74

Sn

71

Pb

72

As

95

Cu

75

Hg

101

Ag

73

Pt

87

Au

89



Ionization is the formation of ions from atoms.   For a better account click  Ionization

Q.1.0              

  A.                                    Give equations to show how these metals react with chlorine and water.

Metal

 

 Ion

With Oxygen

With water

Copper

 

Cu++

Cu + O2

 Cu  + H2O

Calcium

Ca++

Ca + O2

Ca + H2O

Silver

Ag+

Ag + O2

Ag +  H2O

Sodium

Na+

Na + O2

Na+ H2O

           B.    Arrange the four metals according to their activity starting from the most active.

                                                                                                               15  marks.

        Q.2.0

Metal

In air

In Cold water

A

Tarnishes slowly

Bubbles form

B

Shine remains for years.

No reaction

C

Tarnishes quickly

Floats and move about releasing hydrogen.

D

Burns when heated.

No reaction

Some metals have been named as A,B,C and D.  How they reacted in air and with cold water is given in the chart. RE arrange them according to the activity series taking the most active one first.

                                                                                                                      15  maarks

 Q.3.0

  1.   What will be the solid  remainder when a sample of Ag2O is heated in air?.

                                  A,  Ag,    b. O2,  . c..N2 d.   N2

2. Iron can be obtained  by heating an oxide of iron with carbon. What can remain if you       heat calcium carbonate with carbon?

                                  a.  Ca,    b.  CaO, c. CaC,  d.   Ca(OH)2

  3.   Which metal could produce zinc metal, if heated with zinc oxide?   

                       a.  Al., b.  Cu  c. Fe  d. Pb/

  4   Which is the correct  equation for the reaction of magnesium with hot steam.

a.       Mg  +H2 O  MgO  +H2             b. Mg + 2 H2O  →  Mg(OH)2 + H2   

c.  2 Mg + 2H2O → 2MgH2 + O2 d. 2 Mg + 2H2O →2 Mg(OH)2


5.  A,B,C and D  are 4 metals according to the activity series. A is the most active. Which equation could be predicted as possible.

a.      An oxide of A can decompose when heated.       

b .  If the oxide of C is heated with D  we can get  the metal C,

   c.    If D is added to a sulphate solution of B the metal B will be displaced.

  d.     If C is added to a nitrate of D  the metal D will be displaced.

6x5 = 30 marks

Q. 4.0

Select the answers from these words.

Aluminium,    Calcium,  Copper, Iron,  Lead , Mercury, Potassium, Silver, Sodium, , Zinc,

1.    A coloured metal that has been used by man since earliest times.

2.    Size of a pea can produce a purple flame on cold water.

3.    Fairly an active metal but widely used in structural work and utensils.

4.    Slowly reacts with water to form a slightly soluble hydroxide.

5.    Shows a reversible reaction with oxygen.

6.    Widely used and a historic era/an age had been given this name.

7.    The yellow oxide of this metal can be reduced by magnesium to give a heavy metal.

8.    The oxide of this gives off oxygen when heated.

9.    This is used to protect iron as a sacrificial metal

10. Very light , soft and tarnishes instantly in air.

                                                                                                       4 x10 = 40 marks

               For answers click Answer page - A to K.



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