oxidation states of transition metals when reactions occur

sgstudent

When metals such as sodium react with an acid, a salt and hydrogen gas is produced. and we know for sure the oxidation state of sodium in the compound will be +1. But for other metals such as iron, when they rest with acids which oxidation state do I use? I'm unsure if I'm supposed to use the lowest oxidation first as when iron reacts with an acid its oxidation state is +2 first. But for other metals which one do I use first such as copper?

Thanks for. The help guys!

Borek

There is no simple answer to that other than "use standard potentials table" (but I think even then you can be wrong in some specific cases).

If there is nothing else present (that is, the only oxidizing agent is H⁺) iron gets oxidized to Fe(II), as E₀ for Fe(II)/Fe(III) oxidation is way too high.

From the same table you can read copper doesn't dissolve in non-oxidizing acids, so the question about products is a moot.

sgstudent

So for most of the stuff there's no real rule to follow rather its based on empirical data? Thanks for the help Borek!

Borek

Rules are made up from the empirical data, after all it is reality that defines what happens, not rules that we invent.

DrDu

Oxidation state is not a fundamental property of atoms but in fact little more than a mnemotechnics to balance equations. It is quite astonishing that it can be used to systematize to some extent chemical compounds but one should be aware of its limitations.