* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Show all work – Homework 5 –
2-Norbornyl cation wikipedia , lookup
Homoaromaticity wikipedia , lookup
Mössbauer spectroscopy wikipedia , lookup
Nitrogen-vacancy center wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Bose–Einstein condensate wikipedia , lookup
X-ray photoelectron spectroscopy wikipedia , lookup
Magnetic circular dichroism wikipedia , lookup
Ionic compound wikipedia , lookup
Scanning tunneling spectroscopy wikipedia , lookup
Electron paramagnetic resonance wikipedia , lookup
Stability constants of complexes wikipedia , lookup
Debye–Hückel equation wikipedia , lookup
Cluster chemistry wikipedia , lookup
Atomic theory wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Electron configuration wikipedia , lookup
Ultraviolet–visible spectroscopy wikipedia , lookup
Electrochemistry wikipedia , lookup
Coupled cluster wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
Surface properties of transition metal oxides wikipedia , lookup
Solid State Chemistry Show all work Spring 2015 – Homework 5 – Show all work (10 pts) 1. Transition metal oxides containing a metal ion with multiple oxidation states may be non-stoichiometric. The non-stoichiometric compound may accommodate this by a variety of ways, including cation vacancies, oxide ion (anion) vacancies, interstitial cations, or interstitial anions. Soft chemistry techniques were used in the synthesis of two compounds with the approximate composition of cobalt(IV) oxide, which has a tetragonal unit cell containing one cobalt atom and two oxygen atoms. These were characterized using powder X-ray diffraction, density measurements, and elemental analysis. The unit cell is trigonal. The data are summarized in the table below. Determine the most likely way in which the non-stoichiometry was accommodated and support your justification. Sample 1 2 O:Co ratio 2.00 1.92 Co:O ratio 0.50 0.52 Lattice parameters /Å a = 2.8208, c = 4.2403 a = 2.8048, c = 4.2509 Density (g/cm3) 5.17 5.14 2. A possible defect cluster in Fe1-xO is given in the figure below. a) Determine the vacancy:interstitialcy ratio for the cluster b) Assuming this section is surrounded by Fe and O ions in octahedral sites as in the Koch-Kohen cluster, determine the formula of the sample of a sample made totally of such clusters. c) Determine the numbers of Fe2+ and Fe3+ in octahedral sites. 3. Zeolite structures contains pores with different sizes. Download and open the *.diamdoc files in the demo version 4.0.2 of Diamond by Crystal Impact (http://www.crystalimpact.com/diamond/ ). Rotate the structure using the botton. Using the Measure Distances button to determine the distances between atoms of the pore entrance to determine the geometric minimum size of the pore opening. 1 File (Diamdoc) Atom-atom distance in pore opening P-43n-Sodalite-zeolite P63mmc-Gmelinite-zeolite Pm-3m-Zeolite_A_Na12Al12Si12O48 FD3MZ-Faujasite_zeolite 4. Two metal oxide octahedra may share a corner, and edge, and/or a face. Sketch each pair of connected octahedra. What is the formula (MxOy) of each pair of connected octahedra? a) corner-shared _______________ b) edge-shared _____________ c) face-shared _____________ 5. The figure below shows a member of the homologous series WnO3n-1. It contains WO6 octahedra that are corner and edge-sharing. Determine and outline the unit cell. Determine the chemical formula. ____________ Determine the average oxidation state of the W._____________ 6. Zeolite A has a single peak in the 29Si MAS NMR spectrum at 89 ppm and has a Si/Al ratio of 1. Explain these observations. 7. Zeolite A (Ca form), when loaded with platinum, has been found to be a good catalyst for the oxidation of hydrocarbon mixture. If the mixture contains branched chain hydrocarbons, these do not react. Describe a possible reason to explain these observations. 8. In the manganese(II) oxide the Mn2+ ions occupy the octahedral holes in the rock salt structure. a. Describe the splitting of the d-orbitals and assign symmetry labels. b. Assuming the oxide ligand to be a weak field ligand (high spin), populate the d orbitals. c. The total spin of the Mn2+ is _________ d. Explain why the absorption lines due to transitions between the two 3d levels are very weak for Mn2+. 2 9. The energy levels of Nd3+ in Y3Al5O12 that are involved in the laser action of the crystal are shown in the following figure. Describe the processes that occur when the laser is working. 10. Determine the ground state electron configuration for Nd3+. How many microstates are possible for this electron configuration? What is the spin multiplicity? Determine the term symbol for the ground state. 3