Patterns in Redox Potentials

The large exothermic value for AHox (La +) indicates that it is not likely to exist in aqueous solution. The Eu +(aq) ion is known to have a short lifetime in water, even though AH is negative for the oxidation process, so the activation energy for oxidation may be rather high. 

Known and estimated values are listed in Table 2.7. The values for the reduction potential for Ln + + 3 e — Ln are very consistent, with slight irregularities at Eu and Yb. The potential largely depends upon three processes  

Question 2.1 What is the trend in atomic radii, and that in ionic radii, for the lanthanides What are the exceptions to this, and why  

Answer 2.1 The structure of metals is usually described as one in which metal ions are surrounded by a sea of delocalised outer-shell electrons. The greater the number of loosely held electrons, the stronger the metallic bonding and the smaller the atomic radius. If the 

Question 2.2 Using Hess s Law and the A//f forLap2 (—831 kJ/mol) and for LaFsC—1732 kJ/mol), calculate A// for this decomposition reaction. 

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