# Why does zinc increase in weight after being placed in NaOH?

Jun 11, 2017

Of course the mass of zinc does not increase........

#### Explanation:

However, zinc, as an active metal, can be OXIDIZED in basic solution as well as acidic solution........to give the $\text{zincate salt}$, $N {a}_{2} \left[Z n {\left(O H\right)}_{4}\right]$

$\text{Oxidation:}$

$Z n \left(s\right) + 4 H {O}^{-} \rightarrow Z n {\left(O H\right)}_{4}^{2 -} + 2 {e}^{-}$ $\left(i\right)$

$\text{Reduction:}$

${H}_{2} O \left(l\right) + {e}^{-} \rightarrow \frac{1}{2} {H}_{2} \left(g\right) + H {O}^{-}$ $\left(i i\right)$

And we take $\left(i\right) + 2 \times \left(i i\right)$:

$Z n \left(s\right) + 2 {H}_{2} O \left(l\right) + 2 H {O}^{-} \rightarrow Z n {\left(O H\right)}_{4}^{2 -} + {H}_{2} \left(g\right) \uparrow$

You could presumably isolate the zincate ion as its sodium salt, $N {a}_{2} \left[Z n {\left(O H\right)}_{4}\right]$, which complex has clearly a greater mass than the metal equivalent.