Chemistry – Feb 27, 2018 P3 – Nomenclature quiz 6 Objective – Get out solubility/reaction decisions for HMK check P3 – Nomenclature quiz 6 Objective – Driving forces – Net ionic equations, Acids and bases Assignment: Driving forces worksheet 1 Agenda Homework Review Net ionic equations Acids and bases Neutralization reactions Net ionic equations on WB in groups

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.

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-

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: 2 KI(aq) + Pb(NO3)2  PbI2 (s) + 2 KNO3 (aq)

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.

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.

Exit Slip - Homework Exit Slip: Write the Complete ionic equation and the net ionic equation for Pb(NO3)2 (aq) + 2 KOH (aq)  Pb(OH)2 (s) + 2 KNO3 (aq) What’s Due? (Pending assignments to complete.) Finish Driving Forces Worksheet 1 What’s Next? (How to prepare for the next day) Read p473, p286-288, p548-549, p280-282