Solution: Qualitative Analysis for Metallic Elements

Chapter , Problem 78E

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An unknown solid is entirely soluble in water. On addition of dilute HCl, a precipitate forms. After the precipitate is filtered off, the pH is adjusted to about 1 and \(H_{2} S\) is bubbled in; a precipitate again forms. After filtering off this precipitate, the pH is adjusted to 8 and \(H_{2} S\) is again added; no precipitate forms. No precipitate forms upon addition of \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}\). (See Figure 7.23.) The remaining solution shows a yellow color in a flame test (see Figure 7.22). Based on these observations, which of the following compounds might be present, which are definitely present, and which are definitely absent: \(\mathrm{CdS}, \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}, \mathrm{HgO}, \mathrm{ZnSO}_{4}, \mathrm{Cd}\left(\mathrm{NO}_{3}\right)_{2}\), and \(\mathrm{Na}_{2} \mathrm{SO}_{4}\)?

Equation transcription:

Text transcription:

H_{2} S

({NH}_{4})_{2}{HPO}_{4}

{CdS},{Pb}({NO}_{3}\right)_{2},{HgO},{ZnSO}_{4},{Cd}({NO}_{3})_{2}

{Na}_{2}{SO}_{4}