Ch 11 3 Chemical Reactions Solubility Rules Writing

Ch. 11. 3: Chemical Reactions Solubility Rules & Writing Net Ionic Equations Dr. Knorr Honors Chemistry

Solubility Rules Ø Rules that help us predict which compounds will be soluble/insoluble

Solubility Rules All group IA salts are soluble. All ammonium salts are soluble. All salts containing nitrate, acetate, chlorate, and perchlorate are soluble. 4. All salts are containing halides are soluble EXCEPT silver, mercury(I), and lead. 5. All sulfate salts are soluble EXCEPT barium, calcium, strontium, silver, mercury(I), and lead. 6. All salts containing carbonates, phosphates, and chromates are insoluble EXCEPT for rules #1 and #2. 7. All sulfide salts are insoluble EXCEPT for rules #1 and #2 and calcium, strontium, and barium. 8. All hydroxide salts are insoluble EXCEPT rules #1 and #2 and barium and strontium. ** Will be given for a test or quiz, no need to memorize!! 1. 2. 3.

Is it Soluble? Ø Na 3 PO 4 l Yes- (aq) Ø Ba. CO 3 l Yes- (aq) No- (s) Ø Ca 3(PO 4)2 l No- (s) Ø Ni(OH)2 Yes- (aq) Ø (NH 4)2 SO 4 l l No- (s) Ø Ag. NO 3 l Ø Pb. Cl 2 l Ø No- (s) Fe(CH 3 COO)3 l Yes- (aq)

Precipitation Reactions Ø Remember that all ionic compounds are considered strong electrolytes l dissociate completely in water Ø When two solutions are mixed, free ions are floating around Ø They collide together randomly Ø If an ionic compound forms that is insoluble in water, it is called a precipitation reaction

Precipitation Reactions

Types of Equations Ø molecular equation l l overall reaction normal type we have been writing Ø complete ionic equation l all strong electrolytes are broken into ions Ø net ionic equation l l all spectator ions are cancelled out only includes species active in chemical reaction

Types of Electrolytes Ø Break Apart (Strong) l l must be (aq) soluble ionic compounds Ø Don’t break apart (weak/non) l anything (g), (s), (l)

Write the net ionic equations Øsolution of strontium chloride is mixed with solution of potassium sulfate l Sr. Cl 2(aq) + K 2 SO 4(aq) Sr. SO 4(s) + 2 KCl(aq) Øcomplete ionic: l Sr 2+(aq) + 2 Cl-(aq) +2 K+(aq) + SO 42 -(aq) Sr. SO 4(s) + 2 K+(aq) + 2 Cl-(aq) Øspectators: 2 Cl-(aq) and 2 K+(aq) Ønet ionic: l Sr 2+(aq) + SO 42 -(aq) Sr. SO 4(s)

Write the net ionic equations Ø solution of sodium sulfide and solution of iron (II) nitrate are mixed l Na 2 S(aq) + Fe(NO 3)2(aq) 2 Na. NO 3(aq) + Fe. S(s) Ø complete ionic: l 2 Na+(aq) + S 2 -(aq) + Fe 2+(aq) + 2 NO 3 -(aq) 2 Na+(aq) + 2 NO 3 -(aq) + Fe. S(s) Ø spectators: 2 Na+(aq) and 2 NO 3 -(aq) Ø net ionic: l S 2 -(aq) + Fe 2+(aq) Fe. S(s)

Write the net ionic equations Ø Solution of aluminum chloride and solution of silver nitrate are mixed l Al. Cl 3(aq) + 3 Ag. NO 3(aq) 3 Ag. Cl(s) + Al(NO 3)3(aq) Ø complete ionic: l Al 3+(aq) + 3 Cl-(aq) + 3 Ag+(aq) + 3 NO 3 -(aq) 3 Ag. Cl(s) + Al 3+(aq) + 3 NO 3 -(aq) Ø spectators: Al 3+(aq) and 3 NO 3 -(aq) Ø net ionic: l l 3 Cl-(aq) + 3 Ag+(aq) 3 Ag. Cl(s) Cl-(aq) + Ag+(aq) Ag. Cl(s)

Write the net ionic equations Ø Solution of sodium chloride and solution of potassium nitrate are mixed l Na. Cl(aq) + KNO 3(aq) Na. NO 3(aq) + KCl(aq) Ø complete ionic: l Na+(aq) + Cl-(aq) + K+(aq) + NO 3 -(aq) Na+(aq) + NO 3 -(aq) + K+(aq) + Cl-(aq) Ø spectators: everything! Ø net ionic: nothing!

Precipitation Reactions Ø If no insoluble compound forms, no reaction has actually happened Ø It is just a solution with lots of free ions floating around Ø Spectator Ions l free ions not involved in chemical reaction

Tips for writing equations Balance at the beginning 1. l l should stay balanced the whole way through may simplify at the end if necessary All ions should be (aq) – break apart for ionic equation 3. Keep symbols (i. e. - aq, s, l, g) written through entire process 4. Cancel out spectator ions and common ions on both sides for net ionic equation 2.

In Conclusion Ø Remember net ionic equations identify what is ACTIVE in a chemical reaction Ø There are three steps that need to be identified to be able to write a complete net ionic equation Ø Make sure you understand each step! Ø Homework: 11. 3 Practice Problems