Question

For each of the following redox reactions, determine which element is being reduced and which is being oxidized.

(a)    5 C₂H₅OH(aq) + 2 KMnO₄(aq) + 3 H₂SO₄(aq) → 5 C₂H₄O(aq) + 2 MnSO₄(aq) + K₂SO₄(aq) + 8 H₂O(l)

(b)    4 Au(s) + 8 KCN(aq) + O₂(g) + 2 H₂O(l) → 4 K[Au(CN)₂](aq) + 4 KOH(aq)

(c)    MnO₂(aq) + K₂C₂O₄(aq) + 2 H₂SO₄(aq) → MnSO₄(aq) + K₂SO₄(aq) + 2 CO₂(g) + 2 H₂O(l)

Answer 1

a) element is being reduced = Mn

    element is being oxidized = C

b) element is being reduced = O

    element is being oxidized = Au

c)

element is being reduced = Mn

    element is being oxidized = C

explanation:

element being reduced =Mn because +7 oxidation state changes to +2

element being oxidized C because + oxidation state changes to +2

b) Au oxidation state changes 0 to +1 it is oxidation

O oxidation state changes from 0 to -2 so it is reduction