which are the most important reactions that one should surely know in d-block elements?
Important reaction from d-block elements are as follows:
It is prepared by fusion of chromate ore (FeCr2O4) with sodium carbonate in excess of air.
4FeCr2O4 + 8Na2CO3 + 7O2 8Na2CrO4 + 2Fe2O3 + 8CO2
2Na2CrO4 + H2SO4 Na2Cr2O7 + H2O + Na2SO4
Na2Cr2O7 + 2KCl K2Cr2O7 + 2NaCl
Effect of pH on chromate and dichromate ions: The chromates and dichromates are interconvertible in aqueous solution depending upon pH of the solution. The oxidation state of chromium in chromate and dichromate is the same
2 CrO42- + 2H+ Cr2O72- + H2O
Cr2O72- + 2 OH- 2 CrO42-+ H2O
- Potassium dichromate acts as a strong oxidizing agent in acidic medium.
Cr2O72- +14 H+ + 6e- 2 Cr3+ + 7 H2O
- Potassium permanganate acts as a strong oxidizing agent in acidic, neutral or faintly basic medium.
In acidic medium.
MnO4- + 8 H+ + 5 e- Mn2+ + 4 H2O
In neutral or faintly basic medium,
MnO4- + 3 e- + 2 H2O MnO2 + 4OH-
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