c) Sulfur dioxide làm mất màu dung dịch thuốc tím: SO2 + KMnO4 + H2O ⟶ MnSO4 + K2SO4 + H2SO4

Trả lời

c) $\stackrel{+4}{S}{O}_2+K\stackrel{+7}{Mn}{O}_4+H_{2}O\to \stackrel{+2}{Mn}\stackrel{+6}{S}{O}_4+K_2\stackrel{+6}{S}{O}_4+H_2\stackrel{+6}{S}{O}_4$

Ta có:

$\begin{array}{c}5\times \\ 2\times \end{array}\left|\begin{array}{l}\stackrel{+4}{S}\to \stackrel{+6}{S}+2e\\ \stackrel{+7}{Mn}+5e\to \stackrel{+2}{Mn}\end{array}\right.$

Vậy 5SO₂ + 2KMnO₄ + 2H₂O ⟶ 2MnSO₄ + K₂SO₄ + 2H₂SO₄