How to predict (know) the products of the reaction SnO+NaOH?

Question

I would like to know how to complete the reaction $\ce{SnO}+\ce{NaOH ->}$, how can I form a salt and water from this?

I've seen that the complete reaction is:

$$ \ce{SnO + 2NaOH ->Na2SnO2 + H2O} $$

How to know what will be formed?

Answer 1

I've discovered the answer, at least I guess...

The given reaction is

$$ \ce{SnO + 2NaOH -> Sn^{2+} + O^{2-} + 2Na+ + 2OH-} $$

The hidroxy breaks in $\ce{H2O + O^{2-}}$. This released oxigen will get together with the oxigen from the $\ce{SnO}$, to form $\ce{O2^{2-}}$.

$$ \ce{SnO + 2NaOH -> Sn^{2+} + \underbrace{O2^{-2}}_{\textrm{nox = -4}} + 2Na+ + H2O} $$

The oxidation state of this molecule is -4. Performing the double replacement reaction we get

$$ \ce{SnO + 2NaOH -> SnO2^{-2} + 2Na+ + H2O} $$

And finally,

$$ \ce{SnO + 2NaOH -> Na2SnO2 + H2O} $$

What is already balanced.