a.
CrāŗĀ¹Ā + Snāŗā“Ā āĀ CrāŗĀ³Ā + SnāŗĀ²
CrāŗĀ¹ āĀ CrāŗĀ³ + 2eā»
The half-reaction of oxidation: chrome is anĀ electron donor,Ā losses 2 electrons ie it is oxidized
2eā» + Snāŗā“Ā ā SnāŗĀ²
The half-reaction of reduction: tin is anĀ electron acceptor, receives 2 electrons, ieĀ it is reduced
b.
3HgāŗĀ²Ā + 2FeĀ āĀ 3Hg + 2FeāŗĀ³
2FeĀ āĀ 2FeāŗĀ³ + 6eā»Ā
The half-reaction of oxidation: iron is anĀ electron donor,Ā losses 3 electrons ie it is oxidized
6eā» + 3HgāŗĀ²Ā + āĀ 3HgĀ
The half-reaction of reduction: mercury is anĀ electron acceptor, receives 2 electrons, ieĀ it is reduced
c.
2As + 3ClāĀ ā 2AsClā
2As ā 2AsāŗĀ³ + 6eā»Ā
The half-reaction of oxidation: arsenic is anĀ electron donor,Ā losses 3 electrons ie it is oxidized
6eā» + 3ClāĀ ā 6Clā»
The half-reaction of reduction: chlorine is anĀ electron acceptor, receives 1 electron, ieĀ it is reduced
d.
NaBr + ClāĀ āĀ NaCl + BrāĀ
2Brā» āĀ Brā + 2eā»Ā
The half-reaction of oxidation: bromine is anĀ electron donor,Ā losses 1 electron ie it is oxidized
2eā» + ClāĀ ā 2Clā»
The half-reaction of reduction: chlorine is anĀ electron acceptor, receives 1 electron, ieĀ it is reduced
e.
FeāOāĀ + 3COĀ ā 2Fe + 3COā
3CāŗĀ² ā 3Cāŗā“ + 6eā»
The half-reaction of oxidation: carbon is anĀ electron donor,Ā losses 2 electrons ie it is oxidized
6eā» +Ā 2FeāŗĀ³ ā 2FeĀ
The half-reaction of reduction: iron is anĀ electron acceptor, receives 3 electrons, ieĀ it is reduced
