Question

Why does zinc increase in mass after being placed in NaOH?

Answer 1

Because of formation of the zincate species, `[Zn(OH)_4]^(2-)`...

Explanation:

Zinc metal is quite active, and can be oxidized under either acidic or basic conditions......

`"Oxidation.....:"`

`Zn(s) rarr Zn^(2+) + 2e^(-)`

`"Reduction.....:"`

`H_2O + e^(-)rarr 1/2H_2uarr+HO^-`

`"Overall....."`

`Zn(s) + 2H_2O(l) +2HO^(-) rarr H_2(g) + [Zn(OH)_4]^(2-)`