JAMB - Chemistry (2004 - No. 23)
Which of the following acts as both reducing and oxidizing agent?
H2
SO2
H2S
CO2
Uitleg
SO\(_2\) can act as both an oxidizing and reducing agent because it has multiple valencies, with the oxidation state of sulphur ranging from -2 to +6. It can oxidize hydrogen sulphide to sulphur, and carbon monoxide to carbon dioxide. It can lose electrons to other compounds, reducing itself to a lower valency state. For example, SO\(_2\) can reduce ferric to ferrous salts, and acidified potassium iodate to iodine. Therefore, sulphur dioxide, SO\(_2\) can act as both an oxidizing and reducing agent.