Textbook Question
Draw the structure of the following complexes. What are the oxidation state, coordination number, and coordination geometry of the metal in each?
(b) [Co(H2O)5Cl]SO4]
Ch.21 - Transition Elements and Coordination Chemistry
Chapter 21, Problem 76
What role does EDTA4- play as a trace additive to mayonnaise? Would the glycinate ion (H2NCH2CO2-) be an effective substitute for EDTA4-?
Verified step by step guidance1
EDTA^{4-} is a chelating agent, which means it can form multiple bonds with a single metal ion, effectively 'trapping' the metal ion and preventing it from participating in unwanted chemical reactions.
In mayonnaise, EDTA^{4-} is used to bind metal ions such as iron and copper, which can catalyze the oxidation of fats, leading to rancidity and spoilage. By binding these metal ions, EDTA^{4-} helps to preserve the freshness and extend the shelf life of the product.
The glycinate ion (H_2NCH_2CO_2^{-}) is a bidentate ligand, meaning it can form two bonds with a metal ion. This is less effective than EDTA^{4-}, which is a hexadentate ligand and can form up to six bonds with a metal ion, providing a stronger and more stable complex.
To determine if glycinate could be an effective substitute, consider its ability to form stable complexes with metal ions compared to EDTA^{4-}. The stability constant (K_f) of the metal-glycinate complex would need to be high enough to effectively sequester metal ions in the same way EDTA^{4-} does.
Evaluate the practical aspects such as the cost, availability, and any potential impact on the taste or texture of mayonnaise when using glycinate instead of EDTA^{4-}.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Chelation
Chelation is a chemical process where a molecule, known as a chelator, binds to a metal ion to form a stable complex. EDTA<sup>4-</sup> is a well-known chelating agent that effectively sequesters metal ions, preventing them from catalyzing undesirable reactions in food products like mayonnaise. This property helps in preserving the quality and safety of the food by inhibiting oxidation and microbial growth.
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Chelating Agents
Stability of Metal Complexes
The stability of metal complexes is crucial in determining the effectiveness of a chelating agent. EDTA<sup>4-</sup> forms very stable complexes with a wide range of metal ions due to its multiple binding sites. In contrast, the glycinate ion (H<sub>2</sub>NCH<sub>2</sub>CO<sub>2</sub><sup>-</sup>) has fewer binding sites and may not form as stable complexes, potentially making it less effective as a substitute for EDTA<sup>4-</sup> in food applications.
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Food Additives and Safety
Food additives, such as EDTA<sup>4-</sup>, are substances added to food to enhance its safety, quality, and shelf life. The use of chelating agents like EDTA<sup>4-</sup> is regulated to ensure they do not pose health risks. Understanding the role of these additives in preventing spoilage and maintaining food safety is essential for evaluating alternatives like glycinate, which may have different safety profiles and effectiveness.
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02:55Addition Reactions
Related Practice
Textbook Question
(a) Identify the Lewis acid and the Lewis base in the reaction of ethylenediamine (H2NCH2CH2NH2) with Ni2+ to form [Ni(en)3]2+.
(b) Identify the ligands and donor atoms.
(c) Give the coordination number and geometry of the metal in the complex.
Textbook Question
What is the systematic name for each of the following coordination compounds?
(a) [Cu(NH3)4]SO4
(b) Cr(CO)6
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Textbook Question
What is the systematic name for each of the following coordination compounds?
(c) K3[Fe(C2O4)3]
(d) [Co(en)2(NH3)CN]Cl2
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Textbook Question
Write the formula for each of the following compounds.
(a) Tetraammineplatinum(II) chloride
(b) Sodium hexacyanoferrate(III)