Solubility and Net Ionic Equations

Focus on equations with a precipitate.

Total Ionic EquationsWrite the equation (synthesis, decomposition,

etc.)check for reactants and products that are soluble

or insoluble.We usually assume the reaction is in water.Use a solubility table to tell us what

compounds dissolve in water.If the compound is soluble (does dissolve in

water), then the compound splits into its component ions.

If the compound is insoluble (does NOT dissolve in water), then it remains as a compound in solid form (precipitate)

Water dipole-partial charges

Hydrophilic compoundsWhen a soluble compound in is water, the

partial polarity of water molecules interact with the charges on ions to dissolve the compound.

Compounds that are dissolved in water may be termed hydrophilic.

Solubility Chart

Solubilities Not on the Table!Gases only slightly dissolve in waterStrong acids and bases dissolve in water

Hydrochloric, Hydrobromic, Hydroiodic, Nitric, Sulfuric, Perchloric Acids

Group I hydroxides (should be on your chart anyway)

Water slightly dissolves in water! (H+ and OH-)

There are other tables and rules that cover more compounds than your table!

Total Ionic EquationsMolecular Equation:

K2CrO4 + Pb(NO3)2 PbCrO4 + 2KNO3

Soluble Soluble Insoluble Soluble

Total Ionic Equation:2 K+ + CrO4 -2 + Pb+2 + 2 NO3

-

PbCrO4 (s) + 2 K+ + 2 NO3-

Net Ionic Equation:

Pb+2 + CrO4 -2 PbCrO4 (s)

1. Salts containing Group I elements are soluble (Li+, Na+, K+, Cs+, Rb+). Exceptions to this rule are rare. Salts containing the ammonium ion (NH4

+) are also soluble. 2. Salts containing nitrate ion (NO3

-) are generally soluble. 3. Salts containing Cl -, Br -, I - are generally soluble. Important exceptions to this rule are halide salts of Ag+, Pb2+, and (Hg2)2+. Thus, AgCl, PbBr2, and Hg2Cl2 are all insoluble. 4. Most silver salts are insoluble. AgNO3 and Ag(C2H3O2) are common soluble salts of silver; virtually anything else is insoluble. 5. Most sulfate salts are soluble. Important exceptions to this rule include BaSO4, PbSO4, Ag2SO4 and SrSO4 . 6. Most hydroxide salts are only slightly soluble. Hydroxide salts of Group I elements are soluble. Hydroxide salts of Group II elements (Ca, Sr, and Ba) are slightly soluble. Hydroxide salts of transition metals and Al3+ are insoluble. Thus, Fe(OH)3, Al(OH)3, Co(OH)2 are not soluble. 7. Most sulfides of transition metals are highly insoluble. Thus, CdS, FeS, ZnS, Ag2S are all insoluble. Arsenic, antimony, bismuth, and lead sulfides are also insoluble. 8. Carbonates are frequently insoluble. Group II carbonates (Ca, Sr, and Ba) are insoluble. Some other insoluble carbonates include FeCO3 and PbCO3. 9. Chromates are frequently insoluble. Examples: PbCrO4, BaCrO4 10. Phosphates are frequently insoluble. Examples: Ca3(PO4)2, Ag3PO4 11. Fluorides are frequently insoluble. Examples: BaF2, MgF2 PbF2.

Solubility Rules Courtesy Prof. Kenneth W. Busch

Short version-Top rules supersede any lower rules.Group 1 is soluble.NH4

+ is soluble.Nitrate, acetate, or chlorate is soluble.Cl-, Br -, and I- are soluble, but NOT Ag+,

Pb2+, and (Hg2)2+. Silver is NOT soluble unless covered by rules

1-4.Sulfates are soluble, but NOT Ba2+, Ca2+,

Pb2+, Ag+, Sr2+.

Net Ionic EquationsThese are the same as total ionic

equations, but you should cancel out ions that appear on BOTH sides of the equation

Total Ionic Equation:2 K+ + CrO4 -2 + Pb+2 + 2 NO3

- PbCrO4 (s) + 2 K+ +

2 NO3-

Net Ionic Equation:CrO4 -2 + Pb+2 PbCrO4 (s)

Net Ionic EquationsTry this one! Write the molecular, total ionic, and

net ionic equations for this reaction: Silver nitrate reacts with Lead (II) Chloride in hot water.

Molecular: 2AgNO3 + PbCl2 2AgCl(s) + Pb(NO3)2

Total Ionic: 2Ag+1 + 2NO3

1- + Pb+2 + 2Cl -1 2AgCl(s) + Pb+2 + 2(NO3 1- )

Net Ionic: 2Ag+1 + 2Cl -1 2AgCl(s)