Synthesis of chloropentaaminecobalt(lll) chloride

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Experiment 1 (Day 2)

Synthesis of chloropentaaminecobalt(lll) chloride

 

Abstract

The complex compound [Co(NH3)5Cl]Cl2 was synthesized and electrical conductance and infrared spectra were measured to characterize. The percentage yield was calculated ,91.23 % that the error of percentage yield was discussed. The molar conductivity was obtained to determine the number of ions constituting the compound which was not successful. Also, the frequencies of product were examined to observe the peak of ammonia group.

Introduction

 

 In this experiment, [Co(NH3)5Cl]Cl2 was synthesized and the formation and properties of a coordination compound were studied. The experiment involved a coordination compound that is formed between electron pair donors, ligands and electron pair acceptors, the metal atoms. Generally, a coordination compound is made up of a central atom which is bound to ligands. There is many possible ligands that can bond to the central atom, but NH3 was used that donates one pair of electrons to form coordinate bonds. In the formation of chloropentaaminecobalt(lll) chloride, denoted [Co(NH3)5Cl]Cl2, the transition metal which serves as the central atom is cobalt. Since cobalt is involved in six bonds, its coordination number is six, and the structure around the cobalt is octahedral. The synthesis of cobalt(lll) complexes involved oxidation of the cobalt(lll) salt in the presence of the desired ligands. Carbonato compounds made intermediates in the synthesis of cobalt complexes in which carbonate ion was removed by HCl which expelled the carbonate.

 The complex was characterized in terms of conductivity and infrared spectroscopy. Measuring the conductivity of the cobalt coordination compound was necessary to determine how many ions were present in one formula unit of the complex. The expected conclusion was three ions, resulting in a conductance of 235-273.

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 An infrared spectrum is a plot of the absorption intensities of different wavelengths of infrared light. The IR spectrum of [Co(NH3)5Cl]Cl2 consists of absorptions  primarily attributed to the NH3 groups.

Results

Table 1: Result of synthesis of [Co(NH3)5Cl]Cl2

Table 2: Results of Electroconductivity

  • This data was obtained from other groups.

Table 3: Results of IR spectrum of [Co(NH3)5Cl]Cl2

Simple calculation

  1. Theoretical mass

Moles of [Co(NH3)5Cl]Cl2

= mass of Co(NH3)4CO3]NO3 x 1 / (MW of Co(NH3)4CO3]NO3) x MW of [Co(NH3)5Cl]Cl2

= 2.5g x (1/ 249.0695 g/mol ) x 250.4956g/mol

= 2.51g

  1. Percentage yield

= Actual ...

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