Chem 218 Exp 13

# Cobalt ii nitrate reacts with the ammonium carbonate

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Cobalt (II) nitrate reacts with the ammonium carbonate which results in the replacement of nitrate with carbonate. The ammonia has a higher electronegativity than the water, and it is drawn to the cobalt. After the hydrogen peroxide is added, cobalt (II) is oxidized to cobalt (III) due to an electron being transferred to the hydrogen peroxide. Then, the ion binds to NO 3 - in solution to form carbonatotetraamminecobalt(III) nitrate. Absorbance spectrum shows how the absorbance of light depends on the wavelength. And, the maximum wavelength is characteristic of different compounds. The percent yield was 1.46%, and the maximum wavelength was 520 nm. Since I determined that the maximum wavelength was 520 nm for the coordination compound, the energy gap between the levels corresponding to the transition was 228 kJ/ mole. Post Lab Questions 1. Calculate the percent yield for the reaction Theoretical Yield: 1.002 g Co(NO 3 ) 2 x (1 mole/183 g Co(NO 3 ) 2 ) x ( 1 mole cobalt complex/1 mole Co(NO 3 ) 2 ) x (248 g/1 mole cobalt complex) = 1.36 g Actual Yield: 1.99 g Percent Yield: Actual Yield/ Theoretical Yield x 100= 1.99g/1.36g = 1.46% 2. What is λ max for your complex? Using this value, calculate the energy gap (in KJ/mol) between the energy levels corresponding to this transition.

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• Fall '12
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