Explanation:
It is known that the oxidation of [tex]SO_{2}[/tex] to [tex]SO_{3}[/tex] is catalyzed by [tex]NO_{2}[/tex] . In this process, two steps are involved as follows.
(a) [tex]NO_{2}(g) + SO_{2}(g) \rightarrow NO(g) + SO_{3}(g)[/tex]
whereas, the second step is
(b) [tex]2NO(g) + O_{2}(g) \rightarrow 2NO_{2}(g)[/tex]
Balancing the above reaction by multiplying equation (a) by 2 as follows.
(c) [tex]2NO_{2}(g) + 2SO_{2}(g) \rightarrow 2NO(g) + 2SO_{3}(g)[/tex]
Now, on adding both reaction equations (b) and (c) the net reaction equation will be as follows.
[tex]2SO_{2}(g) + O_{2}(g) \rightarrow 2SO_{3}(g) [/tex]
Thus, we can conclude that the equation for the final overall oxidation of [tex]SO_{2}[/tex] by [tex]O_{2}[/tex] to give [tex]SO_{3}[/tex] is as follows.
[tex]2SO_{2}(g) + O_{2}(g) \rightarrow 2SO_{3}(g) [/tex]
