Solubility Rules

• Explain examples of solubility and precipitation at both the particle and symbolic levels.

 • Use a table of solubility rules to predict the

formation of a precipitate.

Additional KEY Termsppt spectator ion

The terms soluble and insoluble are relative terms.

soluble soluble insoluble

solute

Solubility:The amount of solute needed to make a saturated

solution, under given conditions.

Precipitation (ppt) reaction:Formation of an ionic compound that is not soluble in the current solvent.

Usually SR or chemical reactions

Spectator ions - do not participate, remain moving freely in solution.

DR DR

There are many different ways to present RULES for what will dissolve and what will NOT (ppt)

Basic Solubility Rules (View 1)

1. All ionic compounds containing Group 1 elements, H+ and ammonium ion are soluble.

2. All ionic compounds with Group VII elements (other than F) and metals are soluble, except those of Ag+, Hg+1, and Pb+2.

3. All acetates and nitrates are soluble.4. All sulfates are soluble except those of Ba+, Sr+2, Pb+2, Ca+2,

Ag+, Hg+1.

5. Carbonates, hydroxides, oxides, sulfides, phosphates, chromates and dichromates are soluble; ONLY when bonded with those in rule 1.

Basic Solubility Rules (View 2)

Using the Solubility rules:*Assuming the reactants will dissolve… 1. Predict the products of the reaction 2. Check RULES to see if each product will ppt

NaCl(aq) + KBr(aq)

NaCl (s) Na+ (aq) + Cl- (aq)

KBr (s) K+ (aq) + Br - (aq)

NaBr(aq) + KCl(aq)

Indicate if any of the product form a precipitate (ppt).

KOH (aq) + AgNO3 (aq)

Calcium nitrate + sodium carbonate

KNO3 (aq) + AgOH (aq)

Ca(NO3)2 + Na2CO3 CaCO3 + NaNO3

ppt

ppt2

Indicate if any of the product form a precipitate (ppt).

Na2SO4 (aq) + KCl (aq)

Iron (III) chloride + lead (II) nitrate

2 NaCl (aq) + K2SO4 (aq) 2

FeCl3 + Pb(NO3)2 3 2 Fe(NO3)3 + 3 PbCl2 2ppt

AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

The complete ionic equation shows all ions in their dissociated form.

Ag+(aq) + NO3

−(aq) + Na+

(aq) + Cl−(aq) → AgCl(s) + Na+

(aq) + NO3−

(aq)

The net ionic equation shows the actual reaction that occurs – no spectators:

Ag+(aq) + Cl−

(aq) → AgCl(s)

Spectator ions

Write the molecular equation and the net ionic equation for the reaction between aqueous lead (II) nitrate and aqueous potassium iodide.

Pb(NO3)2(aq) + 2 KI(aq) → PbI2(s) + 2 KNO3(aq)

Pb2+(aq) + 2 I−

(aq) → PbI2(s)

Spectator ions

K+ NO3−

CAN YOU / HAVE YOU?

• Explain examples of solubility and precipitation at both the particle and symbolic levels.

 • Use a table of solubility rules to predict the

formation of a precipitate.

Additional KEY Termsppt spectator ion