What is the metal oxidation number in the complex ion, #[Zn(OH)_4]^(2-)#?

2 Answers
Mar 19, 2016

Answer:

#Zn(OH)_4^(2-)# is a complex ion in which the oxidation number of #Zn# is #+II#. Oxidation numbers of hydrogen (#+I#) and oxygen (#-II#) are standard.

Explanation:

How do we know this? Well, look at its formation reaction:

#Zn^(2+) + 4HO^(-) rarr [Zn(OH)_4]^(2-)#

Charge and mass are conserved, as in every chemical equation. The #[Zn(OH)_4]^(2-)# species is a complex ion, for which there are many examples.

Mar 19, 2016

Starting with the common grouping of a hydroxyl (OH) as #O^(-2), H^(+1)# for a net charge of -1. That gives a total of -4 charge for the four OH groups. If the whole molecule has a charge of -2, the Zn must be #Zn^(+2)#. Checking the Periodic Table, this is a highly likely oxidation state (giving up its 4s electrons).