A sample may contain any or all of the following ions: Hg22+, Ba2+, and Mn2+.

(a) No precipitate formed when an aqueous solution of NaCl was added to the sample solution.

(b) No precipitate formed when an aqueous solution of Na2SO4 was added to the sample solution.

(c) A precipitate formed when the sample solution was made basic with NaOH.

Which ion or ions are present in the sample solution? (Select all that apply.)

Mn2 + ions

Ba2 + ions

Hg22 + ions

The ion present in the sample solution is Mn2+

Explanation:

(a) No precipitate formed when an aqueous solution of NaCl was added to the sample solution.

Most chlorides are quite soluble in water except for he H g 2 C l 2, that is an insoluble salt. Since no precipitation formed upon addition of NaCl, H g 2 + was not present in the sample.

(b) No precipitate formed when an aqueous solution of Na2SO4 was added to the sample solution.

The B a S O 4 is an insoluble salt too. Since no precipitation formed upon addition of N a 2 S O 4, the ion B a 2 + was not present in the sample.

(c) A precipitate formed when the sample solution was made basic with NaOH.

As the M n (O H) 2 is insoluble in this last solution, the precipitate formed corresponds to B a S O 4 and H g 2 C l 2 compounds, therefore it can be concluded that the present ion in the sample solution is Mn+2.