Question

Potassium zincate is:

Answer 1

Hint: In a compound if there is Zn atom present as the central atom in the polyatomic anion then we name the anion as zincate.
- Zincates are generally formed by reaction with a solution of alkali.

Complete Solution :
- The branch of chemistry which deals with compounds other than carbon and hydrogen is called inorganic chemistry. In this branch of chemistry we deal with the composition, synthesis, extraction, structure and naming of these inorganic compounds.
- We know that for naming a compound, first we should know the anion and cation present. And we name the compound according to the cation and anions present in it. In some compounds cations and anions present may be polyatomic ones i.e. in them there will be a central ion and other atoms attached to the central atom and it exists as one unit.
- The question given is one example of such compounds.
Here in Potassium Zincate, Potassium is the cation and polyatomic anion is the zincate molecule.
Zincates is the name given as the suffix during the nomenclature of a polyatomic anion which possesses the Zn atom as the central atom in them.
- Zincates have a formulae of $Zn{O}_2^{2-}$ if prepared from the alkali salts
We know that generally zincates are prepared by dissolving zinc oxide or zinc ion in alkali solution.

- Now let’s write the formulae possible for the given compound.
In the lower classes we have studied the elements with their valency shown with respect to the valence electronic configuration.
Brushing up those memory we know that the, potassium ion ($K^{+}$) possess a valency of +1 and the formulae for zincate is $Zn{O}_2^{2-}$ and it possess -2 valency.
By the method of crisscross we could easily find the formulae of potassium zincate.

We get the formulae of potassium zincate as $K_{2}Zn{O}_2$.
Considering only the magnitude of the charge, the sign is not considered in the criss cross method for writing the formulae.

Note: Other units of zincates are $ZnC{l}_4^{2-}$, which is called as tetra chlorozincate ,$Zn(N{O}_3{)}_4^{2-}$ which is tetra nitrite zincate.
- We should know the valence shown by each cation and anion to solve the problems related to writing the formulae of the compounds.