Câu trả lời tốt nhất
(a + 2b)K2Cr2O7 + 6aFeCl2 + (14a + 28b)HCl → (2a + 4b)CrCl3 + 6bCl2 + 6aFeCl3 + (2a + 4b)KCl + (7a + 14b)H2O
Fe2+ → Fe3+ + 1e
2Cl- → Cl2 + 2e
aFe2+ + 2bCl- → aFe3+ + bCl2 + (a + 2b)e……x6
2Cr+6 + 6e → 2Cr+3……………………………………x(a + 2b)
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