KMnO4 and K2CrO7

Question 1

i)MnO2–KOH and O2–>A
A–H+—>B+C
ii)KMnO4–hv–>

Answer 1

i)MnO2–>K2MnO4(o2 or kclo4 or kno3)
K2MnO4—H+–>KMnO4 + MnO2
ii)KMnO4–hv–>K2MnO4 + MnO2 + O2

Question 2

MnO4- and MnO4-2 paramagnetic or diamagnetic at :
i)RT
ii) high temperature

Answer 2

i)diamagnetic and paramagnetic
ii)paramagnetic and paramagnetic

Question 3

Method of Preparation of K2Cr2O7

Answer 3

FeCr2O4+ Na2CO3 –air–>Na2CrO4 + Fe2O3 + CO2
Na2CrO4(aq)–H+–>Na2Cr2O7
(CrO4-2 + H+–>Cr2O7-2)
Na2Cr2O7 + KCl–>K2Cr2O7

Question 4

i)K2Cr2O7–heat–>
ii)CrO3–heat–>
iii)K2Cr2O7 + conc.H2SO4 +KCl(s)–>
iv)K2Cr2O7 + H2O2 + H+ –>A
on standing A—>B+C

Answer 4

i)K2Cr2O7–heat–>K2CrO4 + Cr2O3 + O2
ii)CrO3–heat–>Cr2O3
iii)K2Cr2O7 + conc.H2SO4 + KCl(s)–>CrO2Cl2
iv)A is CrO5,B is Cr2O3, C is O2