Question

Consider the reaction: $Fe+H_{2}O\to F{e}_3{O}_4+H_2$
If the number of electrons lost or gained during the changes is $x$. Then, the value of $x$ is :

Answer 1

Given the reaction:
$Fe+H_{2}O\to F{e}_3{O}_4+H_2$
If the number of electrons lost or gained during the changes is $x$. Then, the value of $x$ is $8$.
The balanced chemical equation is as follows:
$3Fe+4H_{2}O\to F{e}_3{O}_4+4H_2$
The oxidation number of hydrogen changes from $+1$ (in water) to $0$ (in hydrogen molecule).
Thus, net change in the oxidation number of hydrogen per atom is $1$.
There are $8$ H atoms.
Hence, the total change in the oxidation number of $8$ hydrogen atoms is $8$.
Hence, $8$ electrons are involved in the redox reaction.
Hence, $x=8$.