Question

On the basis of the general solubility rules given in Table 4.1, predict which of the following substances are likely to be soluble in water. a. aluminum nitrate b. magnesium chloride c. rubidium sulfate d. nickel(II) hydroxide e. lead(II) sulfide f. magnesium hydroxide g. iron(III) phosphate

Short answer

Using the general solubility rules, the soluble substances in water are: a. Aluminum nitrate (\(Al(NO_3)_3\)) b. Magnesium chloride (\(MgCl_2\)) c. Rubidium sulfate (\(Rb_2SO_4\)) The insoluble substances in water are: d. Nickel(II) hydroxide (\(Ni(OH)_2\)) e. Lead(II) sulfide (\(PbS\)) f. Magnesium hydroxide (\(Mg(OH)_2\)) g. Iron(III) phosphate (\(FePO_4\))

Step-by-step solution

Recall the general solubility rules

First, recall the basic solubility rules: 1. All nitrates (NO3-) are soluble. 2. Most chlorides (Cl-) are soluble, except for silver(I), lead(II), and mercury(I) chlorides. 3. All sulfates (SO4 2-) are soluble, except for barium, calcium, strontium, lead(II), and mercury(I) sulfates. 4. Most hydroxides (OH-) are insoluble, except for alkali metals (Group 1) and barium hydroxides, which are soluble. 5. Most sulfides (S2-) are insoluble, except for alkali metals (Group 1), alkaline earth metals (Group 2), and ammonium sulfides. 6. Most phosphates (PO4 3-) are insoluble, except for alkali metals (Group 1) and ammonium phosphates.

Apply the solubility rules to each substance

a. Aluminum nitrate: Aluminum nitrate has the anion nitrate (NO3-), and all nitrates are soluble. Therefore, aluminum nitrate is soluble in water. b. Magnesium chloride: Magnesium chloride has the anion chloride (Cl-). Most chlorides are soluble, except for silver(I), lead(II), and mercury(I) chlorides. Magnesium is not one of these exceptions, so magnesium chloride is soluble in water. c. Rubidium sulfate: Rubidium sulfate has the anion sulfate (SO4 2-). All sulfates are soluble, except for barium, calcium, strontium, lead(II), and mercury(I) sulfates. Rubidium is not one of these exceptions, so rubidium sulfate is soluble in water. d. Nickel(II) hydroxide: Nickel(II) hydroxide has the anion hydroxide (OH-). Most hydroxides are insoluble, except for alkali metals (Group 1) and barium hydroxides, which are soluble. Nickel is not an alkali metal or barium, so nickel(II) hydroxide is insoluble in water. e. Lead(II) sulfide: Lead(II) sulfide has the anion sulfide (S2-). Most sulfides are insoluble, except for alkali metals (Group 1), alkaline earth metals (Group 2), and ammonium sulfides. Lead is not one of these exceptions, so lead(II) sulfide is insoluble in water. f. Magnesium hydroxide: Magnesium hydroxide has the anion hydroxide (OH-). Most hydroxides are insoluble, except for alkali metals (Group 1) and barium hydroxides, which are soluble. Magnesium is an alkaline earth metal (Group 2), but not an exception, so magnesium hydroxide is insoluble in water. g. Iron(III) phosphate: Iron(III) phosphate has the anion phosphate (PO4 3-). Most phosphates are insoluble, except for alkali metals (Group 1) and ammonium phosphates. Iron is not one of these exceptions, so iron(III) phosphate is insoluble in water.

Summarize the results

Based on the general solubility rules, the following substances are soluble in water: a. Aluminum nitrate b. Magnesium chloride c. Rubidium sulfate The following substances are insoluble in water: d. Nickel(II) hydroxide e. Lead(II) sulfide f. Magnesium hydroxide g. Iron(III) phosphate