The following list contains some common polyatomic ions. using the charge on these ions and the idea of valence, predict the formulas for the following: nitrate no3 - phosphate po4 -3 sulfate so4 -2 acetate c2h3o2 -1 ammonium nh4 + chromate cro4 -2 carbonate co3 -2 dichromate cr2o7 -2 permanganate mno4 -1 potassium chromate

The chemical formula for potassium chromate is

Explanation:

We are given some of the polyatomic ions with their oxidation states. Polyatomic ions are defined as the ions which are formed from the combination of more than 2 atoms.  

We are asked to find the chemical formula for potassium chromate,

For this, only one polyatomic ion is used which is: Chromate having formula

Potassium is the 19th element of the periodic table having electronic configuration of

This element will easily loose 1 electron and will attain an oxidation state of +1 forming an ion of

By using criss-cross method, the oxidation state of the ions are exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

Hence, the chemical formula for this compound is

The formula for potassium chromate is .

Explanation:

The formula for potassium chromate :

Cation in the potassium chromate : Potassium

Anion  in the potassium chromate : chromate

The symbol of potassium ion =

oxidation state on the potassium ion = +1

The symbol of chromate ion =

Oxidation state on the chromate ion = -2

By criss-cross method, teh oxidation states of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

So, the formula for potassium chromate :

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