Test Index

CBSE Class 12 Chemistry 2020 Outside Delhi Set 1 Solved Paper

© examsnet.com
Question : 23 of 37
Marks: +1, -0
Write the balanced chemical equations involved in the preparation of KMnO4\mathrm{KMnO}_4 from pyrolusite ore (MnO2)(\mathrm{MnO}_2).
OR
Write the balanced ionic equations showing the oxidising action of acidified dichromate (Cr2O72−)(\mathrm{Cr}_2\mathrm{O}_7^{2-}) solution with
(i) Iron (II) ion and (ii) Tin (II) ion.
Solution:  
2MnO2+4KOH+O2→2K2MnO42\mathrm{MnO}_2+4\mathrm{KOH}+\mathrm{O}_2 \rightarrow 2\mathrm{K}_2\mathrm{MnO}_4 +2H2O+2\mathrm{H}_2\mathrm{O}
3K2MnO4+2CO2→2KMnO4+MnO2(ppt)3\mathrm{K}_2\mathrm{MnO}_4+2\mathrm{CO}_2 \rightarrow 2\mathrm{KMnO}_4+\mathrm{MnO}_{\underset{\text{(ppt)}}{2}} +2K2CO3+2\mathrm{K}_2\mathrm{CO}_3
OR
(i) Cr2O72−+14H++6Fe2+→2Cr3+\mathrm{Cr}_2\mathrm{O}_7^{2-}+14\mathrm{H}^{+}+6\mathrm{Fe}^{2+} \rightarrow 2\mathrm{Cr}^{3+} +6Fe3++7H2O+6\mathrm{Fe}^{3+}+7\mathrm{H}_2\mathrm{O}
(ii) Cr2O72−+3Sn2++14H+→2Cr3++3Sn4+\mathrm{Cr}_2\mathrm{O}_7^{2-}+3\mathrm{Sn}^{2+}+14\mathrm{H}^{+} \rightarrow 2\mathrm{Cr}^{3+}+3\mathrm{Sn}^{4+} +7H2O+7\mathrm{H}_2\mathrm{O}
© examsnet.com
Go to Question:
Prev Question
Next Question