SOLUBILITY AND PRECIPITATION RULES

Solubility

The ability to dissolve or break down into its component ions in a liquid

Example: NaCl is soluble

Completely dissolves in water AgCl is insoluble

Stays a solid in water

Solubility Rules

Li, Na, K, NH4, NO3, C2H3O2 are all soluble

Cl, Br, and I are soluble except when paired with Ag, Cu, Hg2, Ni, and Pb

SO4 is soluble except with Ag, Fe, Sr, Ba, Pb, or Ca

OH, S, CO3, PO4 are insoluble except when paired with Li, Na, K, NH4

Let’s Try

Determine whether each of the follow compounds is soluble or insoluble: AgBr

Insoluble – Br is normally soluble but not when its with Ag

CaCl2 Soluble

Pb(NO3)2

Soluble – NO3 is always soluble

NH4Cl Soluble - NH4 and Cl are both soluble

Precipitation Reactions

A reaction in which a solid is formed upon mixing two aqueous solutions

Example: Potassium Iodide + Lead Nitrate

2 KI (aq) + Pb(NO3)2 (aq) -> 2 KNO3 (aq) + PbI2 (s)

Your Turn

Write an equation for the precipitation reaction that occurs (if any) when solutions of sodium carbonate and copper (II) chloride are mixed.

Write an equation for the precipitation reaction that occurs (if any) when solutions of lithium nitrate and sodium sulfate are mixed.

Na2CO3 (aq) + CuCl2 (aq) ->

LiNO3 (aq) + Na2SO4 (aq) ->

Writing Chemical Equations

Molecular Formula An equation that shows the complete neutral

formula for every compound

Complete Ionic Equation An equation that shows the reactants and

products as they are present in solution

AgNO3 (aq) + NaCl (aq) -> AgCl (s) + NaNO3 (aq)

Ag+ (aq) + NO3- (aq) + Na+ (aq) + Cl-

(aq) -> AgCl (s) + Na+ (aq) + NO3

- (aq)

Writing Chemical Equations cont.

Spectator Ions Ions that are present on both the reactant and

product side. They do not participate in the reaction

Net Ionic Equation An equation that eliminates the spectator ions

and shows only the elements or compounds that are participating

Ag+ (aq) + NO3- (aq) + Na+ (aq) + Cl-

(aq) -> AgCl (s) + Na+ (aq) + NO3

- (aq)

Ag+ (aq) + Cl- (aq) -> AgCl (s)

You Try

Consider the following reaction:

What is the complete ionic equation? Which ions are the spectators? What is the net ionic equation?

HCl (aq) + NaOH (aq) -> H2O (l) + NaCl (aq)