Coordination Complexes- Cobalt (III) Ammine Complexes
Anusha Ambaselkar Lab B05 A-1
January 28, 2021
Abstract:
In this experiment, tetraamminecarbonatocobalt (III) nitrate (1.114g, 32.6%) and
pentaamminechlorocobalt(III) chloride (0.454g, 89.0%) was synthesized. Ammonium carbonate
solution and cobalt (II) hexahydrate solution was mixed, evaporated and filtrated to prepare the
intermediate of tetraamminecarbonatocobalt (III) nitrate. A sample of this intermediate was used
to synthesize pentaamminechlorocobalt(III) chloride by replacing the carbonate ligand with a
chlorine ligand through evaporation and filtration. Conductance measurements were obtained of
the two products as well as three stock solutions of KCl, MgCl2 and Na3PO4ᐧ 12 H2O. These
were then converted to molar conductivities using a formula in order to assign the number of
ions present in the ionic species. Tetraamminecarbonatocobalt (III) nitrate (116.96(Sᐧ cm2/mol),
2 ions) and pentaamminechlorocobalt(III) chloride (235.23(Sᐧ cm2/mol), 3 ions).
Introduction:
Conductance of a coordination complex with a known concentration can be used to
determine the number of ions in solution. The conductivity determined experimentally however
reflects all ions that are mobile and carry current as well as dependent on concentration.[1] This
concentration dependence prohibits the comparison between different solutions thus molar
conductivity (Am) is used between known ionic species that consist of different numbers of ions.
The Am ranges that correspond with the number of ions help determine if the experimental
product has the same number of ions as the known ionic species.
The purpose of this experiment was to synthesize two cobalt (III) coordination
complexes. In part A of the experiment, tetraamminecarbonatocobalt (III) nitrate was made and
in part B of the experiment pentaamminechlorocobalt(III) Chloride was made. After their
This study source was downloaded by 100000850872992 from CourseHero.com on 02-10-2023 23:01:14 GMT -06:00
https://www.coursehero.com/file/83007395/Coordination-of-Cobalt-Complex-Chem-333pdf/
, synthesis, the conductance of each cobalt complex was measured using a conductivity meter.
This conductance was then converted into molar conductance (Am) in order to compare with
KCl, MgCl2, and Na3PO4ᐧ 12 H2O stock solutions to prove the number of ions of the
experimental products.
Product Reactions:
Tetraamminecarbonatocobalt (III) nitrate [Co(NH3)4CO3]NO3
10 Co(NO3)2 + 26NH3 + 10(NH4)2CO3 + H2O2 → 8 NH4NO3OH + 10 [Co(NH3)4CO3]NO3
Pentaamminechlorocobalt(III) Chloride [Co(NH3)5Cl]Cl2
[Co(NH3)4CO3]++ 2HCl → [Co(NH3)4(OH2)Cl]2++ CO2 + Cl-
[Co(NH3)4(OH2)Cl]2+ + NH3 → [Co(NH3)5(OH2)]3+ + Cl-
[Co(NH3)5(OH2)]3+ + 3HCl → [Co(NH3)5Cl]Cl2 + H2O + 3H+
Methods:
Part A: Preparation of Tetraamminecarbonatocobalt(III) Nitrate
Ammonium carbonate (36.4 mmol, 3.505g) was dissolved in water (10.0mL) along with
concentrated aqueous NH3 (NH4OH) to form solution A.[1] Cobalt (II) Nitrate Hexahydrate (8.6
mmol, 2.510g) was dissolved in water to form solution B. Solution A and solution B was mixed
resulting in a solution that was a deep purple opaque color. 30% Hydrogen Peroxide (2.0mL)
was slowly added dropwise into the solution while stirring continuously. Some bubbles occurred
during this process. This solution was poured into an evaporating dish to be heated (70℃) on a
hot plate for approximately 25 minutes in order to concentrate to less than half the original
amount. During the evaporation process, ammonium carbonate (1g, 10.4mmol) was added in
small portions to the evaporating dish. Using vacuum filtration, filter this solution and cool the
filtrate using an ice water bath. After 7 minutes of crystallization, the solution was filtered again
through vacuum filtration resulting in reddish-pink precipitate left in the funnel. After washing
with water (2.1mL) and cold ethanol (3 x 5mL), a bright fuschia pink solid powder was isolated
(1.114g, 32.6%
This study source was downloaded by 100000850872992 from CourseHero.com on 02-10-2023 23:01:14 GMT -06:00
https://www.coursehero.com/file/83007395/Coordination-of-Cobalt-Complex-Chem-333pdf/
Anusha Ambaselkar Lab B05 A-1
January 28, 2021
Abstract:
In this experiment, tetraamminecarbonatocobalt (III) nitrate (1.114g, 32.6%) and
pentaamminechlorocobalt(III) chloride (0.454g, 89.0%) was synthesized. Ammonium carbonate
solution and cobalt (II) hexahydrate solution was mixed, evaporated and filtrated to prepare the
intermediate of tetraamminecarbonatocobalt (III) nitrate. A sample of this intermediate was used
to synthesize pentaamminechlorocobalt(III) chloride by replacing the carbonate ligand with a
chlorine ligand through evaporation and filtration. Conductance measurements were obtained of
the two products as well as three stock solutions of KCl, MgCl2 and Na3PO4ᐧ 12 H2O. These
were then converted to molar conductivities using a formula in order to assign the number of
ions present in the ionic species. Tetraamminecarbonatocobalt (III) nitrate (116.96(Sᐧ cm2/mol),
2 ions) and pentaamminechlorocobalt(III) chloride (235.23(Sᐧ cm2/mol), 3 ions).
Introduction:
Conductance of a coordination complex with a known concentration can be used to
determine the number of ions in solution. The conductivity determined experimentally however
reflects all ions that are mobile and carry current as well as dependent on concentration.[1] This
concentration dependence prohibits the comparison between different solutions thus molar
conductivity (Am) is used between known ionic species that consist of different numbers of ions.
The Am ranges that correspond with the number of ions help determine if the experimental
product has the same number of ions as the known ionic species.
The purpose of this experiment was to synthesize two cobalt (III) coordination
complexes. In part A of the experiment, tetraamminecarbonatocobalt (III) nitrate was made and
in part B of the experiment pentaamminechlorocobalt(III) Chloride was made. After their
This study source was downloaded by 100000850872992 from CourseHero.com on 02-10-2023 23:01:14 GMT -06:00
https://www.coursehero.com/file/83007395/Coordination-of-Cobalt-Complex-Chem-333pdf/
, synthesis, the conductance of each cobalt complex was measured using a conductivity meter.
This conductance was then converted into molar conductance (Am) in order to compare with
KCl, MgCl2, and Na3PO4ᐧ 12 H2O stock solutions to prove the number of ions of the
experimental products.
Product Reactions:
Tetraamminecarbonatocobalt (III) nitrate [Co(NH3)4CO3]NO3
10 Co(NO3)2 + 26NH3 + 10(NH4)2CO3 + H2O2 → 8 NH4NO3OH + 10 [Co(NH3)4CO3]NO3
Pentaamminechlorocobalt(III) Chloride [Co(NH3)5Cl]Cl2
[Co(NH3)4CO3]++ 2HCl → [Co(NH3)4(OH2)Cl]2++ CO2 + Cl-
[Co(NH3)4(OH2)Cl]2+ + NH3 → [Co(NH3)5(OH2)]3+ + Cl-
[Co(NH3)5(OH2)]3+ + 3HCl → [Co(NH3)5Cl]Cl2 + H2O + 3H+
Methods:
Part A: Preparation of Tetraamminecarbonatocobalt(III) Nitrate
Ammonium carbonate (36.4 mmol, 3.505g) was dissolved in water (10.0mL) along with
concentrated aqueous NH3 (NH4OH) to form solution A.[1] Cobalt (II) Nitrate Hexahydrate (8.6
mmol, 2.510g) was dissolved in water to form solution B. Solution A and solution B was mixed
resulting in a solution that was a deep purple opaque color. 30% Hydrogen Peroxide (2.0mL)
was slowly added dropwise into the solution while stirring continuously. Some bubbles occurred
during this process. This solution was poured into an evaporating dish to be heated (70℃) on a
hot plate for approximately 25 minutes in order to concentrate to less than half the original
amount. During the evaporation process, ammonium carbonate (1g, 10.4mmol) was added in
small portions to the evaporating dish. Using vacuum filtration, filter this solution and cool the
filtrate using an ice water bath. After 7 minutes of crystallization, the solution was filtered again
through vacuum filtration resulting in reddish-pink precipitate left in the funnel. After washing
with water (2.1mL) and cold ethanol (3 x 5mL), a bright fuschia pink solid powder was isolated
(1.114g, 32.6%
This study source was downloaded by 100000850872992 from CourseHero.com on 02-10-2023 23:01:14 GMT -06:00
https://www.coursehero.com/file/83007395/Coordination-of-Cobalt-Complex-Chem-333pdf/
