1. Chemistry – Feb 21, 2018 P3 – Nomenclature quiz 6
Pick up 2 handouts when done.
Objective –
Driving forces
Assignment:
Driving forces worksheet 1
Agenda
Homework Review
Types of driving forces
Precipitation reactions
Solubility rules
Net ionic equations
Acids and bases
Neutralization reactions

2. Driving Force
We can write many kinds of reactions on paper, but for them to actually occur, there must be some kind of driving force. Otherwise a simple mixture will happen with no reaction.
Driving Forces:
Formation of a solid
Formation of water
Formation of a gas
Transfer of electrons
Determines a second classification
Note: Any given reaction may have more than one driving force. But if it has none, it will not happen.

3. 1) Formation of a solid When two ionic solutions are mixed…
Sometimes a solid forms. Reaction happens.
Solid formation is a driving force. Called a precipitation reaction.
Sometimes no reaction happens.
How do you know which? Experiments.
Patterns: Solubility rules
Chapter 7, Unnumbered Figure 1, Page 219

4. Solubility Rules – Observations
All common compounds of alkali and ammonium ions are soluble.
All nitrates, acetates, and chlorates are soluble.
All binary compounds of the halogens with metals are soluble,
except those of Ag, Hg(I), Pb(II).
All sulfates are soluble, except those of Ba, Ca, Sr, Ag, Hg(I), Pb(II).
Carbonates, hydroxides, oxides, and phosphates are insoluble, except for alkali and ammonium ions.
Sulfides are insoluble except for Ba, Ca, Sr, Mg, alkali and ammonium.

5. Solubility Rules: Soluble Ionic (aq)
Compounds Containing:
Important exceptions
NO3-
None
C2H3O2-
ClO3-
Cl-
Ag+, Hg22+ , Pb2+
Br- I-
SO42-
Ag+, Hg22+ , Pb2+, Ba2+, Ca2+, Sr2+

6. Solubility Rules: Insoluble Ionic (s)
Compounds Containing:
Important exceptions
CO32-
NH4+ and alkali ions (Li+, Na+, K+, Rb+…)
O2-
NH4+ and alkali ions
PO43-
OH-
Ba2+, Ca2+, Sr2+, NH4+ and alkali ions
S2-
Ba2+, Ca2+, Sr2+, Mg2+ , NH4+ and alkali ions

7. Solubility Rules (all in one view)
Soluble
Insoluble (Precipitates)
Li+, Na+, K+, NH4+ (primary rule)
NO3-, C2H3O2-, ClO3-
Cl-, Br-, I-
Ag+, Hg22+ , Pb2+
SO42-
Ba2+, Ca2+, Sr2+
CO32-, O2-, PO43-
OH-
Ba2+, Ca2+, Sr2+, Mg2+
S2-

8. Using solubility rules
Use to determine whether a written reaction will actually happen or not by providing the state descriptors
Precipitates are usually a driving force for double displacement reactions between ionic compounds.
If no product is a solid, the reaction does not happen.
Ex: CaCl2 + K2SO4  2 KCl + CaSO4
Ex: 2 LiNO3 + Pb(C2H3O2)2  2 LiC2H3O2 + Pb(NO3)2
Ex: (NH4)2O + AlCl3  NH4Cl + Al2O3
Ex: BaI2 + Na2S  2 NaI + BaS
Soluble
Insoluble (Precipitates)
Li+, Na+, K+, NH4+ (primary rule)
NO3-, C2H3O2-, ClO3-
Cl-, Br-, I-
Ag+, Hg22+ , Pb2+
SO42-
Ba2+, Ca2+, Sr2+
CO32-, O2-, PO43-
OH-
Ba2+, Ca2+, Sr2+, Mg2+
S2-

9. Net Ionic Equations
For precipitation reactions, there are three ways to represent the equation.
Molecular equation
Complete ionic equation
Net ionic equation
Ions not participating in the net ionic equation are called spectator ions
Ex: KI(aq) Pb(NO3)2  PbI2 (s) KNO3 (aq)

10. 2) Formation of water: Acids and Bases
Acids are molecular compounds that dissociate to form hydrogen ions, H+.
6 acids dissociate completely and are called strong acids. (memory item)
HCl HBr HI HNO3 H2SO4 HClO4
All other acids are weak acids that split into ions only a little bit.
Bases dissociate in water to form hydroxide ion, OH-
Hydroxides of alkali and alkaline earth metals are strong bases.

11. 2) Formation of water: Acids and Bases
Acids react with bases to form water and an ionic salt.
Formation of water is a driving force.
Ex: HC2H3O2 (aq) + NaOH(aq)  H2O (l) + NaC2H3O2 (aq)
Net ionic equations can be found for acid base reactions too.
Weak acids are the ONLY (aq) substance that you DO NOT SPLIT when determining a net ionic equation.

12. Exit Slip - Homework Exit Slip: none
What’s Due? (Pending assignments to complete.)
Start the Driving Forces Worksheet (Page 1 only)
What’s Next? (How to prepare for the next day)
Read p473, p , p , p