Chapter 7, Problem 114DIA

Water samples often contain dissolved ions such as ${\text{Ca}}^{2+}{\text{and Fe}}^{2+}.$

The presence of these ions can often be detected by adding a precipitation agent –a substance that causes one of the dissolved ions to precipitate. For example, if sodium chloride is added to a water sample containing dissolved ${\text{Ag}}^{+}$, a white precipitate forms. If no precipitate forms, then the water sample does not contain dissolved ${\text{Ag}}^{+}$. Use the solubility rules from Section 7.5 and the date provided to determine the ions present in the water samples.

a. Water Sample A may contain ${\text{Ag}}^{+}{\text{. Ca}}^{2+}.andC{u}^{2+}.$

Use the tabulated date to determine the ions present in Sample A.

Substance Added to Water Sample A	Observation
Nacl	No precipitate forms
$N{a}_{2}S{O}_4$	Precipitate forms
$N{a}_2\text{C}{O}_3$(after filtering off	Precipitate forms
precipitate form previous step)

b. Water Sample B many contain ${\text{Hg}}_2{}^{\text{2+}}{\text{.Ba}}^{\text{2+}}{\text{. and Fe}}^{\text{2+}}\text{.}$

Use the tabulated date to determine the ions present in Sample B.

Substance Added to Water Sample B	Observation
KCl	Precipitate forms
${\text{K}}_{\text{2}}{\text{SO}}_{\text{4}}$ (after filtering off precipitate from previous step)	No precipitate forms
${\text{K}}_{\text{2}}{\text{CO}}_{\text{3}}$	Precipitate forms