1. Reactions in Aqueous Solutions
Prentice-Hall Chapter 11.3
Dr. Yager

2. Objectives
Describe the information found in complete and net ionic equations.
Predict the formation of a precipitate in a double-replacement reaction.

3. Structures in limestone caverns are formed when carbon dioxide converts calcium hydrogen carbonate into calcium carbonate. The calcium carbonate precipitates and forms dramatic stalactites and stalagmites. You will learn to predict the formation of precipitates and write equations to describe the reactions that produce them.

4. Net Ionic Equations Salts dissociate into cations and anions in water.
Chemical reactions taking place in water are aqueous reactions.
Standard Equation
Complete Ionic Equation
Net Ionic Equation

5. Complete Ionic Equation
Standard Equation
AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)
Complete Ionic Equation
Ag+(aq)+NO3-(aq)+Na+(aq)+Cl-(aq)
AgCl(s)+Na+(aq)+NO3-(aq)
The ions crossed out in red
don’t participate

6. Ag+(aq) + Cl-(aq) AgCl(s)
Spectator Ions
Ag+(aq)+NO3-(aq)+Na+(aq)+Cl-(aq)
AgCl(s)+Na+(aq)+NO3-(aq)
The ions crossed out are called spectator ions.
Ag+(aq) + Cl-(aq) AgCl(s)
This is the net ionic equation and only shows
particles directly involved in the chemical change.

7. An ion that appears on both sides of an equation and is not directly involved in the reaction is called a spectator ion.
The net ionic equation is an equation for a reaction in solution that shows only those particles that are directly involved in the chemical change. It is balanced with respect to both mass and charge.

8. A Precipitate is Formed

9. Sodium ions and nitrate ions are not changed during the chemical reaction of silver nitrate and sodium chloride, so the net ionic equation is:

11. 3Ca2+(aq) + 6OH-(aq) + 6H+ (aq) + 2PO43-(aq)
Ca3(PO4)2(s) + 6H2O(l)
This is both the complete
and net ionic equation!
(no spectator ions!)

12. Predicting the Formation of a Precipitate
Precipitation can be predicted by the rules of solubility of ionic compounds.
Solubility: How much solid will dissolve in a solution.
When two ionic compounds are mixed, the cations can change partners.
If the partners are insoluble, then they precipitate out of solution.

13. Remember these ions
CO Carbonate
PO Phosphate
CrO42- Chromate
S Sulfide
OH Hydroxide

14. Will a Precipitate Form?
Sodium nitrate is soluble but carbonate is insoluble. The net ionic equation is

15. Will a Precipitate Form?
Al2(SO4)3 + NH4OH ?
CaCl K2SO ?

16. Will a Precipitate Form?
Al2(SO4)3 + NH4OH Al(OH)3(s) Yes

17. Remember these ions
CO Carbonate
PO Phosphate
CrO42- Chromate
S Sulfide
OH Hydroxide

18. Will a Precipitate Form?
Al2(SO4)3 + NH4OH Al(OH)3(s) Yes
CaCl K2SO CaSO4(s) Yes

19. What Happens?
Ag(NO3) and Na2SO4
NH4Cl and Ba(NO3)2
Pb(NO3)2 and HCl

20. What Happens? Ag(NO3) and Na2SO4 Ag2(SO4)(s) ppt NH4Cl and Ba(NO3)2
Pb(NO3)2 and HCl
Ag2(SO4)(s) ppt

21. Remember these ions
CO Carbonate
PO Phosphate
CrO42- Chromate
S Sulfide
OH Hydroxide

22. What Happens? Ag(NO3) and Na2SO4 Ag2(SO4)(s) ppt NH4Cl and Ba(NO3)2
Pb(NO3)2 and HCl
Nothing

23. What Happens? Ag(NO3) and Na2SO4 Ag2(SO4)(s) ppt
NH4Cl and Ba(NO3)2 Nothing
Pb(NO3)2 and HCl
PbCl2(s) ppt

24. FeO(aq) + 2HClO4(aq)  H2O(l) + Fe(ClO4)2(aq)
Identify the correct net ionic equation for the following reaction and the spectator ions, if they exist.
FeO(aq) + 2HClO4(aq)  H2O(l) + Fe(ClO4)2(aq)
Fe2+(aq) + O2-(aq) + 2H+(aq) + 2ClO4-(aq)  H2O(l) + Fe2+(aq) + 2ClO4-(aq); no spectator ion
O2-(aq) + 2H+(aq)  H2O(l); Fe2+ and ClO4- are spectator ions
FeO(aq) + 2H+(aq)  H2O(l) + Fe2+(aq); ClO4- is the spectator ion
FeO(aq) + 2HClO4(aq)  H2O(l) + Fe(ClO4)2(aq); no spectator ion

25. FeO(aq) + 2HClO4(aq)  H2O(l) + Fe(ClO4)2(aq)
Identify the correct net ionic equation for the following reaction and the spectator ions, if they exist.
FeO(aq) + 2HClO4(aq)  H2O(l) + Fe(ClO4)2(aq)
Fe2+(aq) + O2-(aq) + 2H+(aq) + 2ClO4-(aq)  H2O(l) + Fe2+(aq) + 2ClO4-(aq); no spectator ion
O2-(aq) + 2H+(aq)  H2O(l); Fe2+ and ClO4- are spectator ions
FeO(aq) + 2H+(aq)  H2O(l) + Fe2+(aq); ClO4- is the spectator ion
FeO(aq) + 2HClO4(aq)  H2O(l) + Fe(ClO4)2(aq); no spectator ion

26. 2. Which one of the following products of double-replacement reactions would NOT form a precipitate?
AgCl
PbSO4
Mg(OH)2
Mo(NO3)2

27. 2. Which one of the following products of double-replacement reactions would NOT form a precipitate?
AgCl
PbSO4
Mg(OH)2
Mo(NO3)2

28. 3. Which reaction will NOT produce a precipitate from aqueous solution?
Hg2(NO3)2 + KCl
FeSO4 + Ba(OH)2
Pb(NO3)2 + Na2CO3
NaBr + Al2(SO4)2

29. 3. Which reaction will NOT produce a precipitate from aqueous solution?
Hg2(NO3)2 + KCl
FeSO4 + Ba(OH)2
Pb(NO3)2 + Na2CO3
NaBr + Al2(SO4)2

32. Colors of Some Common Water-Insoluble Materials
Carbonates, CO32-
Ag2CO3 = yellow CuCO3 = pale blue
BaCO3 = white CaCO3 = white
Chlorides, Cl-
AgCl = white Hg2Cl2 = white
PbCl2 = white CuCl = white
Hydroxides, OH-
AgOH = grey-brown Cu(OH)2 = pale blue
Fe(OH)3= rust red Ni(OH)2 = pale green
Pb(OH)2= white Zn(OH)2 = white
Iodides, I-
AgI = yellow Hg2I2 = yellow-orange
PbI2 = yellow CuI = brown
Sulfides, S2-
Ag2S = black CuS = black
Fe2S3 = black HgS = black
NiS = black PbS = black
Sulfates, SO42-
BaSO4 = white PbSO4 = white