J.R. S. answered 04/18/19
Ph.D. University Professor with 10+ years Tutoring Experience
This is a redox reaction and can be balanced by the half reaction method:
Sb goes from 5+ to 3+ so it has been reduced
Mn goes from zero to 2+ so it has been oxidized
Sb2O5 + 4e- + 6H+ ===> 2SbO+ + 3H2O Reduction half reaction
2Mn ====> 2Mn2+ + 4e- Oxidation half reaction
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1Sb2O5 + 2Mn + 6H+ ===> 2SbO+ + 2Mn2+ + 3H2O balanced for mass and charge