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salz14a
Assemble models of Cu2+complex ions
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* Left: In the previous
experiment a colour change from light blue (K) to green (NaCl) or to
dark blue (NH3) took place after adding table salt or ammonia
solution.
Explanation:
Ther
copper ion (Cu2+) in the center is surrounded by 6 water molecules
sitting at the 6 corners of a double pyramide (octahedron): [Cu
(H2O)6]2+ (aq)
* Photo
2 Assemble a model of this copper
complex ion by welding coloured beads: Take
a small silver bead as a model of the copper ion.
* Fix around it 4 red beads
(models of the O atoms of water molecules) in a horizontal orientaion with
90° angles. Red bead Nr. 5 fix to the top of the pyramid. A complete
model of a water molecule fix from below.
* Photo
3 The green colour of the the 2. solution is caused by an
exchange of one water ligand by one chloride ion [Cu
(H2O)5(Cl-)]+(aq).
* Replace one red bead in
the model by a big green one (model of a chloride ion).
*
Right
The dark blue colour of the 3. solution is caused by an exchange of
4 water ligands by 4 ammonia molecules: [Cu (H2O)2(NH3)4]2+
(aq).
* Replace four red beads
in the model by four blue ones (models of ammonia molecules).