THE D-BLOCK TRANSITION ELEMENTS ASSIGNMENT

1. Describe the preparation of potassium dichromate from chromite ore.

2. Describe the preparation of potassium permanganate from pyrolusite. 

3. .Co+2 is stable in aqueous solution but in the presence of complexing reagent it is easily oxidised.

4. .The chemistry of actinoid elements is not so smooth as lanthanoid. Justify this statement. 

 

 

ANSWERS

1. Preparation of sodium chromate
4FeCr2O4 + 16NaOH + 7O2 → 8NaCrO4 + 2Fe2O3 + 8H2O
Conversion of sodium chromate into sodium dichromate
2Na2CrO4 + conc.H2SO4 → Na2Cr2O7 + Na2SO4 + H2O
Conversion of sodium dichromate to potassium dichromate
Na2Cr2O7 + 2KCl → K2Cr2O7 + 2NaCl

2. MnO2 + 2OH− + O2 → MnO42− + H2O
MnO42− + Cl2 → MnO4− + 2Cl−

 

3. In the presence of strong field complexing reagents, it is oxidized to Co (III). Although the 3rdionization energy for Co is high, but the higher amount of crystal field stabilization energy (CFSE) released in the presence of strong field ligands overcomes this ionization energy.

4. Lanthanoids display a limited number of oxidation states because the energy difference between 4f, 5d, and 6s orbitals is quite large. On the other hand, the energy difference between 5f, 6d, and 7s orbitals is very less. Hence, actinoids display a large number of oxidation.

Mugisa Geofrey and SOLOMON TATWEBWA

Mugisa Geofrey Zziwa is a learning facilitator with Ultimate MultiMedia Consult. With knowledge of the following topics:  Digital Pedagogy training or digital teaching skills, how to integrate ICT in teaching.  Journalism and the Internet/Computers (How internet helps journalism)  Basic web design & CMS and Multimedia Content publishing  Digital security and safety basics for journalists  Best practices for ensuring safety online  Data Mashups  Collaborative digital content development tools  Live streaming and Live reporting  Immersive Storytelling tools and practices  Among others I have conducted a number of trainings which include: • Multimedia Journalism and Digital Safety training for university Students held in Makerere University, Kampala International University and Cavendish University and sponsored by the American Embassy Uganda. • Digital Pedagogy training for Science Technology Engineering and Mathematics (STEM) Teachers held in Iganga Girls SSS in Iganga District for Eastern region Uganda, St. Maria Gorretti in MPigi District for Central region Uganda, and Teso College ALOET for the Karamoja region Uganda. Sponsored by Forum for African Women Educationalists Uganda (FAWEU) Training Teachers on integration of ICT in teaching and delivering lessons to students. • Digital Pedagogy at American Center for Teachers by Teachers In Need (TIN) Uganda. • Facilitator on Digital Pedagogy with ICT Teachers Association Uganda (ITAU) at American Center, Kyebambe Girls SSS in FortPortal for western region Uganda, Dr. Obote College Boro Boro Lira for Nothern Region Uganda.

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