Experiment
30: Relative Stabilities of some Complex Ions
Name: ___________________ ( ) Form
7 S
Results Table 30
|
Ligand |
H2O |
Cl- |
ox |
en |
edta |
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|
Complex
ion |
Cu(H2O)42+ |
CuCl42- |
Cu(ox)22- |
Cu(en)22+ |
Cu(edta)2- |
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|
Colour |
|
|
|
|
|
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|
Stability
constant |
--- |
4.0 x
10 mol dm |
2.1 x
10 mol dm |
--- |
6.3 x
10 mol dm |
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Predictions (P) and Results (R). Ö = replacement, ´ = none
|
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|
Test |
P |
R |
P |
R |
P |
R |
P |
R |
P |
R |
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|
Add H2O |
--- |
--- |
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|
|
|
--- |
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Add Cl- |
|
|
--- |
--- |
|
|
--- |
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Add ox |
|
|
|
|
--- |
--- |
--- |
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Add en |
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|
|
|
|
|
--- |
--- |
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|
Add
edta |
|
|
|
|
|
|
--- |
|
--- |
--- |
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Questions
1. Could you have made any tentative predictions without
knowing stability constants?
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2. Estimate the approximate stability constant for Cu(en)22+.
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3. One
of the ligand exchange reactions appeared to be readily reversible. Which one
was this?
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4. Calculate
the ratio [Cu(H2O)42+(aq)] / [CuCl42-(aq)]
for the following values of [Cl-(aq)]:
(a) 5.0 mol dm-3 (in saturated NaCl)
(b) 0.050 mol dm-3 (in dilute NaCl).
How do these ratios help to
explain the reversible nature of the ligand exchange?
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The End