Questions: Which of the following compounds are insoluble? (please select all that apply) Fe(OH)3 Ba(OH)2 (NH4)2 CO3 Ca3(PO4)2 Ag2 SO4 Rb2 S

Transcript text: 1 3 points Which of the following compounds are insoluble? (please select all that apply) $\mathrm{Fe}(\mathrm{OH})_{3}$ $\mathrm{Ba}(\mathrm{OH})_{2}$ $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}$ $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}$ $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ $\mathrm{Rb}_{2} \mathrm{~S}$

Solution

Solution Steps

Step 1: Understanding Solubility Rules

To determine which compounds are insoluble, we need to apply general solubility rules for ionic compounds in water:

Hydroxides ($\mathrm{OH}^-$) are generally insoluble, except for those of alkali metals and $\mathrm{Ba(OH)_2}$, which are soluble.
Carbonates ($\mathrm{CO}_3^{2-}$) are generally insoluble, except for those of alkali metals and ammonium ($\mathrm{NH_4^+}$).
Phosphates ($\mathrm{PO}_4^{3-}$) are generally insoluble, except for those of alkali metals and ammonium.
Sulfates ($\mathrm{SO}_4^{2-}$) are generally soluble, except for those of $\mathrm{Ba^{2+}}$, $\mathrm{Pb^{2+}}$, $\mathrm{Ca^{2+}}$, and $\mathrm{Ag^+}$.
Sulfides ($\mathrm{S}^{2-}$) are generally insoluble, except for those of alkali metals, alkaline earth metals, and ammonium.

Step 2: Applying Solubility Rules to Each Compound

$\mathrm{Fe(OH)_3}$: Hydroxides are generally insoluble, and $\mathrm{Fe(OH)_3}$ is not an exception.
$\mathrm{Ba(OH)_2}$: This is an exception to the hydroxide rule and is soluble.
$(\mathrm{NH_4})_2\mathrm{CO_3}$: Ammonium compounds are soluble, so this is soluble.
$\mathrm{Ca_3(PO_4)_2}$: Phosphates are generally insoluble, and this is not an exception.
$\mathrm{Ag_2SO_4}$: Sulfates are generally soluble, but $\mathrm{Ag_2SO_4}$ is an exception and is insoluble.
$\mathrm{Rb_2S}$: Sulfides of alkali metals are soluble, so this is soluble.