Which substance is oxidized in each reaction?
(a) 2 H2(g) + O2(g) → 2 H2O(l)
(b) 4 Al(s) + 3 O2(g) → 2 Al2O3(s)
(c) 2 Al(s) + 3 Cl2(g) → 2 AlCl3(s)
Solution: Here, we are going to identify the substance that is oxidized in the given reactions.
The term “oxidation” is defined as the addition of oxygen/electronegative element to a substance or removal of hydrogen/ electropositive element from a substance. The substance which undergoes oxidation are said to be oxidized.
Whereas the term “reduction” is defined as removal of oxygen/electronegative element from a substance or addition of hydrogen/ electropositive element to a substance.
- In the first reaction, hydrogen adds up oxygen and hence undergoes oxidation. Thus, H2 is oxidized.
- In the second reaction, aluminium adds up oxygen and hence undergoes oxidation. Thus, Al is oxidized.
- In the third reaction, aluminium adds up the electronegative chlorine atom and hence undergoes oxidation. Thus, Al is oxidized.