Question

2. Suppose that FeO is added as impurity to Cu20. a) If Fe2+ substitutes for Cut, what kind of vacancies would you expect to form, if any? b) Based on your answer in a) how many vacancies are created per Fe2+ added? Justify your answer. (2p) 3. Which element is more soluble in Ni: Cu or Co? Justify your answer using Hume-Rothery rule. (2p)

Answer 1

2 ) when Fe²⁺ substitutes Cu⁺ ion , each Fe²⁺ ion substitute two Cu⁺ ion in which position is filled by Cu⁺ and other remain vacant.since it was initially position of a cation ,it is called cationic vacancies.

One added Fe²⁺ creat one cationic vacancy.

3 ) Cu completely soluble in Ni.
according to Hume - Rotherery rule Cu - Ni system have

1)same valency and same lattice structure.

2) atomic size is similar

3 ) approximately same electronegativity