DEPARTMENT OF CHEMISTRY FACULTY SCIENCE AND MATHEMATICS
SULTAN IDRIS EDUCATION UNIVERSITY
LABORATORY REPORT
INTRODUCTION TO INORGANIC CHEMISTRY
(SKT1013)
STUDENT’S NAME 1. WAN AHMAD HAKIM BIN WAN
KAMARUZAMAN
2. NURUL FARHIDA BINTI OTHMAN
MATRIC NUMBER 1. E20161014530
2. E20161014441
TITLE OF EXPERIMENT 1 : COMPLEX ION OF
EXPERIMENT NICKEL(II) CHLORIDE
DATE 17 NOVEMBER 2017
LABORATORY MAKMAL KIMIA 7 ARAS 3 BLOK 3
LECTURER’S NAME DR SITI MUNIRAH BINTI SIDIK
TITLE: COMPLEX ION OF NICKEL (II) CHLORIDE
OBJECTIVES:
1. To account for a colour change in a complex ion due to ligand substitution
METHODOLOGY:
1. 5 mL of 0.1M NiCl2 were placed in each of FIVE test tubes.
2. 5 drops of concentrated NH3 was added in the first test tube.
3. 5drops of ethylenediamine was added in the second test tube
4. 5 drops of 1M KCN was added in the third test tube
5. 5 drops of EDTA was added in the fourth test tube.
6. The ligand-containing solutions were added excessively into any solution that
precipitate formed. The colour change in each test tube was compared with the colour
of solution in test tube which contains only 𝑁𝑖𝐶𝑙2.
RESULTS:
REACTION OBSERVATION
1 5 mL of 𝑁𝑖𝐶𝑙2 Light green colour formed
2 5 mL of 𝑁𝑖𝐶𝑙2 + 5 drops of 𝑁𝐻3 Pale blue colour and
participated formed
3 5 mL of 𝑁𝑖𝐶𝑙2 + 5 drops of Purple colour formed
ethylenediamine
4 5 mL of 𝑁𝑖𝐶𝑙2 + 5 drops of KCN Green yellowish colour
and participated formed
5 5 mL of 𝑁𝑖𝐶𝑙2 + 5 drops of EDTA Light green colour formed
DISCUSSION:
In test tube 2 solution of NiCl2 were added with ammonia NH3 was changed the
colour of the solution from light green to light turquoise and participated [Ni(H2O)2(NH3)4]2+
also formed. The two nickel(II) complexes are octahedral in shape with a co-ordination
number of 6.The overall charge on the nickel(II) hydroxide complex remains 2+ because both
ligands are electrically neutral. This is another example of a nickel complex ligand exchange
reaction where six ammonia molecules replace six water molecules. Ligand substitution may
be incomplete, so with lower concentrations and excess volume aqueous ammonia the pale
blue hexammine complex ion is formed from the hexaaquanickel(II) ion a typical ligand
substitution reaction giving the hexaamminenickel(II) ion.
[Ni(H2O)6]2+ + 6NH3 →[Ni(NH3)6]2+ + 6H2O
For test tube 3 chelation substitution reaction was occur where a bidentate or
multidentate ligand displaces a numerically greater monodentate (unidentate) ligands.
[Ni(NH3)6]2+ + 3en [Ni(en)3]2+ + 6NH3
In test tube 4 Ni2+ forms the tetracyanonickelate(II) ion, [Ni(CN)4]2–(which is
precipitate that formed) a square planar anionic complex with the cyanide ion (CN–)., in this
ligand exchange reaction, the nickel(II) complex ion shape changes from octahedral to square
planar, the co-ordination number changes from 6 to 4, but the oxidation state of nickel
remains at +2.Due changed of coordination number the solution was changed it colour from
light green to green yellowish and also formed a precipitate of [NiCN4]2–.
[Ni(H2O)6]2++ 4CN–→ [NiCN4]2–+ 6H2O
The complex with EDTA is also readily formed in test tube 5. EDTA is an even more
powerful chelating agent for the same ion tend to increase the greater the chelating power of
an individual ligand in terms of the ligand bond formed as more particles are formed by the
polydentate ligands displacing the unidentate ligands. The replacing ligand on [Ni(H2O)6]2+
doesn’t changed the colour of the solution nor forming of precipitation.
[Ni(H2O)6]2++ EDTA4– → [Ni(EDTA)]2– + 6H2O
CONCLUSION:
Conclusion that was made was that whenever there was a colour change in a solution,
there was a new compound created using NiCl2 and the ion being tested. For example, when
NH3 was tested with any solution, the colour of the entire solution changed to pale blue and
[Ni(NH3)6]2+ was formed and also formed a precipitate in test tube 2.
REFERENCES:
1. http://shodhganga.inflibnet.ac.in/bitstream/10603/51157/12/12_chapter%205.pdf
2. Brown, Lemay, Bursten and Murphy, Chemistry The Central Science 11E, Pearson
Education, pages 1014-1021.
