Question

Question #d0498

Answer 1

For every oxidation there is a reduction; and for every reduction there is an oxidation.

Explanation:

`2Na+FeCl_2 rarr 2NaCl + Fe`

Sodium is oxidized; iron is reduced.

`HC-=CH + 5/2O_2 rarr 2CO_2 + H_2O`

Carbon is oxidized; oxygen is reduced.

`2PbS + 3O_2 rarr2SO_2 + 2PbO`

Oxygen is reduced, sulfur is oxidized.

`2H_2+O_2 rarr2H_2O`

Dihydrogen is oxidized; oxygen is reduced.

`AgNO_3 + Cu rarr CuNO_3 + Ag`

Copper is oxidized; silver is reduced.

All the oxidations feature an increase in oxidation state of the species that is oxidized. Likewise, all reductions feature a decrease in oxidation number of the species that is reduced. You might want to look up the method of half equations for the balancing of redox reactions.