Why Use a High Phenanthroline to Iron Mole Ratio in Iron Concentration Analysis?

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The discussion centers on the use of a high phenanthroline to iron mole ratio in iron concentration analysis, specifically in the context of determining iron in a tablet. The original mole ratio was stated as 52.8:1, later corrected to 5.2:1, which raises questions about the necessity of excess phenanthroline. The complex formed, [Fe(phen)3]2+, has a 3:1 ratio of phen to Fe, suggesting that excess phenanthroline ensures complete complexation of iron. This excess is crucial for accurate determination of iron concentration, as it enhances the color intensity of the complex, improving measurement precision. Understanding the rationale behind using excess phenanthroline is essential for effective lab practices in iron analysis.
corinnab
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1. This is a question about a lab.
The absorbing solution used in the lab had a mole ratio of phen to Fe of 52.8:1
However, the complex [Fe(phen)3]2+ has a mole ratio of 3:1 for phen:Fe

[Fe(phen)3]2+ is a coloured complex and we were determing iron concentration in a tablet.

I don't understand why we used a solution with such a high mole ratio, would appreciate any help!
 
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EDIT: the ratio in the absorbing solution is 5.2:1 I made a mistake
So what i would like to know is why the excess 0-phenanthroline in the absorbing solution?
 
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You were determining the unknown concentration of iron in the tablet and used an excess of the reagent to determine iron.
 
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