Precipitation Reactions Solubility Rules Precipitation Reactions Precipitation Rxn

Precipitation Reactions & Solubility Rules

Precipitation Reactions Precipitation Rxn: A reaction that produces an insoluble product, a. k. a… a precipitate – Insoluble: Does NOT dissolve in water (not aqueous!) these substances are labeled (s) for solid Important to remember: (s) = SOLID = NOT SOLUBLE IN WATER!!! (aq) = AQUEOUS = SOLUBLE IN WATER!!!

Find the Precipitate… Ag. NO 3(aq) + KCl(aq) Ag. Cl(s) + KNO 3(aq) Silver Chloride is a solid, (s). It does NOT dissolve in water—it’s a PRECIPITATE! Review From Yesterday: Can you write total and net ionic equations for this reaction?

Precipitation of Silver Chloride Molecular Equation: Ag. NO 3(aq) + KCl(aq) Ag. Cl(s) + KNO 3(aq) Total Ionic Equation: Ag+(aq) + NO 3 -(aq) + K+(aq) + Cl-(aq) Ag. Cl(s) + K+(aq) + NO 3 -(aq) Net Ionic Equation: Ag+(aq) + Cl-(aq) Ag. Cl(s) Spectator Ions: NO 3 - & K+

Precipitation of Silver Chloride Ag+ NO 3‾ K+ K+ NO 3‾ Cl‾ Precipitate: Ag. Cl Spectator Ions: NO 3 - & Ag. Cl K+

Predicting Precipitation Reactions • How do we know whether a certain compound is aqueous or solid? – (How do we know whether it is SOLUBLE or not? ) • We need SOLUBILITY RULES in order to: – Determine if a precipitate is formed in a reaction – Write correct Total and Net Ionic equations

Solubility Rules (Describe solubility of substances in WATER) Notice the ions that are soluble NO MATTER WHAT they form compounds with! These ions will ALWAYS be SPECTATOR IONS!!!

Predicting Precipitation Reactions • Will a precipitate (s) form when solutions of Calcium Chloride and Sodium Carbonate are mixed? This is a double replacement reaction (don’t forget to balance!) Ca. Cl 2(? ) + Na 2 CO 3(? ) Ca. CO 3(? ) + 2 Na. Cl(? )

Predicting Precipitation Reactions • Will a precipitate (s) form when solutions of Calcium Chloride and Sodium Carbonate are mixed? Ca. Cl 2(aq) + Na 2 CO 3(aq) Ca. CO 3(s) + 2 Na. Cl(aq) Yes! ppt = Ca. CO 3 (Calcium Carbonate = chalk!)

• Now that we have labeled each substance using the SOLUBILITY RULES, we should be able to write Total Ionic and Net Ionic Equations Ca. Cl 2(aq) + Na 2 CO 3(aq) Ca. CO 3(s) + 2 Na. Cl(aq) Total Ionic: Ca+2(aq) + 2 Cl- (aq) + 2 Na+(aq) + CO 3 -2(aq) Ca. CO 3(s) + 2 Na+(aq) + 2 Cl-(aq) Net Ionic: Ca+2(aq) + CO 3 -2(aq) Ca. CO 3(s) Na+ Ca+2 Cl‾ CO 3‾ 2 Cl‾ Na+ Ca. CO 3

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