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Exercises (Advanced Inorganic Chemistry) 1. Explain the difference between a thermodynamically and a kinetically controlled reaction.
2. Explain the term unit cell and give examples for the unit cells of different close packings.
3. Calculate the packing density (space filling) for a cubic primitive and a cubic face centered packing.
4. Explain the differences between covalent, metallic and ionic radius. Which correlation exists between ionic radius and coordination number?
5. How does the atomic radius change throughout the periodic table? Which types of elements have maximum/minimum radii?
6. Calculate the space filling for a body centered cubic unit cell.
7. Explain Braggs law of X-Ray diffraction with respect to constructive and destructive interference.
8. Sketch the possible reaction pathes between two solid grains in a high temperature solid state reaction.
9. Which point defects ar the most important ones in solids? How are they associated with cations and anions? Name typical solids in which these defects occur.
10. Explain the basic law (1st law of Fick) for the diffusion of ions in a solid in the presence of a concentration gradient. Name four container materials for solid state reactions.
11. Which general difference exists between diffusion coefficients in the bulk, the surface and at grain boundaries for one and the same ion? Which relation holds for the temperature dependence of the diffusion coefficient?
12. Explain the basic aspects of a chemical transport reaction and the hydrothermal synthesis.
13. Czochralski growth and zone refining are two important methods for the growth of pure silicon crystals. Describe them?
14. Explain the terms CVD, MBE and epitaxy.
15. Calculate the optimal r(cation)/r(anion) for a threefold and a fourfold planar coordination of anions around a cation.
16. Assume a cubic or hexagonal close packing of anions of type C Which chemical formulas result if atoms of type A fill all tetrahedral and atoms of type B fill all octahedral holes? Assume atoms of type A to fill 12.5% of the tetrahedral and atoms of type B 25% of the tetrahedral holes. Which chemical formula results?
17. Which structure type results if you fill all octahedral holes in a hexagonal close packing ?
18. Sketch the rutile and the perovskite structure. Which structure type results if half of the tetrahedral holes in a hexagonal close packing of anions are filled by cations in an ordered way.
19. How is the lattice enthalpy defined and how the Born repulsion? Explain the importance of the Madelung constant.
20. Illustrate some general trends for ionic radii. Which dependence exists between coordination number and ionic radius.
21. Calculate the shortest distance between an anion and a cation in the fluorite structure (lattice constant. 500 pm). Describe the mutual coordinations of cations and anions.
22. Assume WC to crystallize in the rock salt structure. Describe the mutual coordination of W and C.
23. The element Ta is bcc and has an atomic radius of 0.143 nm at 20 ºC. Calculate a value for its lattice constants in Å.
24. The element W crystallizes in the bcc structure with lattice constants 3.16 Å. Calculate a value for its atomic radius in nm.
25. Pb is fcc and has a lattice constant of 0.495 nm. Calculate a value for the atomic radius of a Pb atom in Å.
26. Calculate a value for the density of fcc Nickel from its lattice constant a=0.352 nm and its atomic mass of 58.71 g/mol.
27. The lattice constant for bcc Fe at 20 ºC is 2.87 Å and its density is 7.87 g/cm3. Calculate a value for its atomic mass.
28. How many neighbours (Na or Cl !) has an Na+ ion in an NaCl structure in its (a) first, (b) second and (c) third coordination sphere?
29. Assume the lattice constants of the following cubic rock salt type structures to be 545 pm (MgSe), 591 pm (CaSe), 623 pm (SrSe) and 662 pm (BaSe). Calculate the cation radii. To determine the Se2- radius, assume that the Se2- ions are ion contact in MgSe.
30. Calculate the enlargement factor of surface if you grind a 1 cm3 cube of a solid material into smaller cubes with an edge length of 100 µm.