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7/31/2019 Metal Displacement
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7/31/2019 Metal Displacement
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Concept Experiment
Interpret Data Evaluation
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K +Na+
Ca+2
Mg+2 Al +3 Zn+2 Fe+2 Sn+2 Pb +2
H+ Cu+2 Hg+2 Ag+
Au+
M
O
R
E
E
L
E
C
TR
O
P
O
S
IT
I
V
E
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ELECTROCHEMICAL SERIESCation
K +Na+
Ca+2
Mg+2 Al +3 Zn+2 Fe+2 Sn+2 Pb +2 H+ Cu+2 Hg+2
Ag+
Au+
The MORE electropositivemetal is able to displacea LESS electropositive metalfrom its salt solution
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Concept:
Zinc
Copper(II) sulphate solution(Salt solution)
Brown solid
Note: Salt solution: sulphate / nitrate/ chloride / carbonate*
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Zinc is higher than copper in ECS Zinc is able to displace copper from
copper(II) sulphate solution
Chemical Equation:
Zn + CuSO 4 ZnSO 4 + Cuatom ion
ion
atom
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Before Reaction
Zn
copper(II) sulphate solution
Cu+2
Cu+2
Zn
Zn
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After reaction
Zinc dissolved
[ atom change to ion]
Copper(II) sulphate solution
Brown solid[ ion change to atom]
Zn2+
Zn+2
Cu
Cu
Blue solution change toColourless
[ concentration of Cu2+
ion decreased]
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Chemical Equation:
Zn + CuSO 4 ZnSO 4 + Cuatom ionion atom
HALF Equation:Zn Zn 2+ + 2e
Cu 2+ + 2e Cu
IONIC Equation:
Zn+ Cu2+
Zn2+
+ Cu
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But..
When copper is put in zinc sulphatesolution,
There is No change??????? Copper try to displace zinc
But Cu is lower than Zn is ECS Cu is not able to displace zinc .
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How can we construct theelectrochemical series based on the
displacement of metals ?
Idea :If metal X is able to displace metal Y from Y chloride solution,SoX is more electropositive than YOr
X is higher than Y in the ECS
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How can we know that displacementreaction takes place ?.
When you can observe these changes :New solid depositedSolutions colour changed Metal used dissolved / thinnerTest tube feels hot
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Data & Observation
Metal Coppernitrate
Leadnitrate
Zincnitrate
Magnesiumnitrate
copper
Lead
Zinc
Magnesium
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Metal Coppernitrate
Leadnitrate
Zinc nitrate Magnesiumnitrate
Copper X X x
Lead Leaddissolved/brown S
x X
Zinc ZincdissolvedOR brownsolid
Zincdissolved/ Grey S
X
Magnesium Mgdissolved/Brown S
Mgdissolved/Grey S
Mgdissolved/Grey S
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1. Magnesium is able to displace copper, lead and zincSomagnesium > coppermagnesium > leadmagnesium > zinc
Interpret the data
1. Zinc is able to displace copper, lead and zincSomagnesium > coppermagnesium > leadmagnesium > zinc
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Conclusion
Arrange the metals in descending order
of tendency to release electron is :
Mg > Zn > Pb > Cu
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Equation
Metal Solution Half Equation
Zinc Leadnitrate
Ionic Equation
Zn Zn+2 + 2e
Pb+2 + 2e Pb
Zn + Pb+2 Zn+2 + Pb
Zinc become thinner / dissolvedGrey solid deposited
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Test yourself.. Put a copper strip into a test tube
contains silver nitrate solution. State the observation
Write the half equations
Silver nitrate solutioncopper
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1. Predict whether take
A. Ada tindak balas
B. Tiada tindak balas
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Manakah antara berikut mewakili setengahpersamaan bagi tindak balas yang berlakudalam tabung uji itu.
A. Pb+2 + Zn Pb + Zn+2
B. Pb + Zn+2 Pb +2 + Zn
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Manakah antara berikut mewakili setengahpersamaan bagi tindak balas yang berlakudalam tabung uji itu.
A. Pb+2 + Zn Pb + Zn+2
B. Pb + Zn+2 Pb +2 + Zn
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Manakah antara berikut mewakili setengahpersamaan bagi tindak balas yang berlakudalam tabung uji itu.
A. Pb+2 + Zn Pb + Zn+2
B. Pb + Zn+2 Pb +2 + Zn
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ELECTROCHEMICAL SERIES
Themoreelectropositive
metal is able todisplace thelesselectropostivemetal from itssalt solution
K +Na+ Ca+2 Mg+2
Al +3
Zn+2
Fe+2 Sn+2 Pb +2 H+ Cu+2 Hg+2
Ag+ A +