Ch. 11.3: Chemical Reactions Writing Net Ionic Equations & Solubility Rules Honors Chemistry

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

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

Precipitation Reactions

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

Solubility Rules 1. All group IA salts are soluble. 2. All ammonium salts are soluble. 3. 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!!

Is it Soluble?  Na 3 PO 4 Yes- (aq) Yes- (aq)  PbCl 2 No- (s) No- (s)  AgNO 3 Yes- (aq) Yes- (aq)  (NH 4 ) 2 SO 4 Yes- (aq) Yes- (aq)  BaCO 3 No- (s)  Fe(CH 3 COO) 3 Yes- (aq)  CaSiO 3 No- (s)  Ni(OH) 2 No- (s)

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

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

Tips for writing equations 1. Balance at the beginning should stay balanced the whole way through should stay balanced the whole way through may simplify at the end if necessary may simplify at the end if necessary 2. 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

Write the net ionic equations  solution of strontium chloride is mixed with solution of potassium sulfate SrCl 2 (aq) + K 2 SO 4 (aq)  SrSO 4 (s) + 2KCl(aq) SrCl 2 (aq) + K 2 SO 4 (aq)  SrSO 4 (s) + 2KCl(aq)  complete ionic: Sr 2+ (aq) + 2Cl - (aq) +2K + (aq) + SO 4 2- (aq)  SrSO 4 (s) + 2K + (aq) + 2Cl - (aq) Sr 2+ (aq) + 2Cl - (aq) +2K + (aq) + SO 4 2- (aq)  SrSO 4 (s) + 2K + (aq) + 2Cl - (aq)  spectators: 2Cl - (aq) and 2K + (aq)  net ionic: Sr 2+ (aq) + SO 4 2- (aq)  SrSO 4 (s) Sr 2+ (aq) + SO 4 2- (aq)  SrSO 4 (s)

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

Write the net ionic equations  Solution of aluminum chloride and solution of silver nitrate are mixed AlCl 3 (aq) + 3AgNO 3 (aq)  3AgCl(s) + Al(NO 3 ) 3 (aq) AlCl 3 (aq) + 3AgNO 3 (aq)  3AgCl(s) + Al(NO 3 ) 3 (aq)  complete ionic: Al 3+ (aq) + 3Cl - (aq) + 3Ag + (aq) + 3NO 3 - (aq)  3AgCl(s) + Al 3+ (aq) + 3NO 3 - (aq) Al 3+ (aq) + 3Cl - (aq) + 3Ag + (aq) + 3NO 3 - (aq)  3AgCl(s) + Al 3+ (aq) + 3NO 3 - (aq)  spectators: Al 3+ (aq) and 3NO 3 - (aq)  net ionic: 3Cl - (aq) + 3Ag + (aq)  3AgCl(s) 3Cl - (aq) + 3Ag + (aq)  3AgCl(s) Cl - (aq) + Ag + (aq)  AgCl(s) Cl - (aq) + Ag + (aq)  AgCl(s)

In Conclusion  Remember net ionic equations identify what is ACTIVE in a chemical reaction  There are three steps that need to be identified to be able to write a complete net ionic equation  Make sure you understand each step!  Homework: 11.3 Practice Problems