Question

Which of the following 0.300 M solutions would contain the highest concentration of potassium ions?

Answer 1

Here is a list of 0.300 M solutions that you can consider to select which has the highest concetration of potassium ions:

Select one:

a. potassium oxide

b. potassium phosphate

c. potassium hydrogen carbonate

d. potassium hypochlorite

e. potassium iodide

Answer:

• Option b. potassium phosphate

Explanation:

First, you must write the chemical formula of each one of the potasssium compounds. Then, assume all the compounds ionize 100%.

Since all the solutions have the same concentrations, by assuming 100% ionization, the ionization equations will show which one produces the highest number of potassium ions, K⁺¹, and that is the solution with the highest concentration of such ions.

1. Chemical formulae

Compound                                              Formula

a. potassium oxide                                  K₂O                                

b. potassium phosphate                          K₃PO₄    

c. potassium hydrogen carbonate          KHPO₃

d. potassium hypochlorite                       KClO₄

e. potassium iodide                                 KI

2. Dissociation (ionization):

• a. potassium oxide, K₂O

           K₂O does not dissociate but react with water to product KOH, then KOH dissociates, but there is not such thing as a 0.300 M solution of K₂O.

• b. potassium phosphate:

       K₃PO₄ → 3K³⁺ + PO₄¹⁻                3 K⁺¹ ions per unit formula

• c. potassium hydrogen carbonate          

       KHPO₃ →  K⁺¹ + HPO₃⁻¹               1 K⁺¹ ion per unit formula

• d. potassium hypochlorite                      

        KClO₄ → K⁺¹ + HClO₄⁻¹                1 K⁺¹  ion per unit formula

• e. potassium iodide                                  

          KI → K⁺¹ + I⁻¹                                1 K⁺¹ ion per unit formula.

Hence, the 0.300 M solution of potasssium phosphate produces the highest concentration of potassium ions.