And Net Ionic Equations Precipitation And Net Ionic Equations

Precipitation When two solutions are mixed, a combination of ions may occur and the resulting compound may be only slightly soluble (insoluble) General rules of solubility may be given (but be aware these are GENERAL)

Solubility Rules (Water) Most solutions with sodium, potassium or ammonium ions are soluble Most nitrates, acetates and chlorates are soluble Most chlorides are soluble (except silver, mercury (I) and lead). Lead (II) chloride soluble in hot water Most sulfates soluble (except barium, strontium and lead)

Solubility Rules Continued Most carbonates, phosphates and silicates are insoluble (except sodium, potassium or ammonium) Most sulfides are insoluble (except calcium, strontium, sodium, potassium or ammonium)

Precipitation Use solubility rules to predict what happens when two solutions are mixed Example: silver nitrate solution mixed with sodium chloride solution AgNO3 → Ag+ + NO3- NaCl → Na+ + Cl- New compounds would be AgCl and NaNO3 AgCl is insoluble, NaNO3 is soluble

Net Ionic Equation Net ionic equation involves ONLY those ions that form the insoluble precipitate First write the overall reaction Determine which substance (if any) is precipitate Ions that do not form precipitate are spectator ions and are not included in net ionic equation Net ionic equation includes only non-spectator ions and preciptated compounds

Sample Problem 14-2 What precipitate forms when aqueous solutions of zinc nitrate and ammonium sulfide are mixed. Zn(NO3)2(aq) + (NH4)2S(aq) → 2NH4NO3(?) + ZnS(?) Ammonium nitrate is soluble Spectator ions are ammonium and nitrate Zinc sulfide is not soluble Ions that form precipitate are zinc and sulfide

Sample problem 14-2 continued Zn(NO3)2(aq) + (NH4)2S(aq) → 2NH4NO3(aq) + ZnS(s) Net ionic equation: Zn+2(aq) + S-2(aq) → ZnS(s)

Now you do it! Read pages 427-430 Do practice problems 1-4 page 430