Chemistry – Feb 21, 2019 _____Pb(NO3)2  _____PbO + _____NO2 + _____O2 P3 – Do one mastery quiz and then answer this question: Balance the following chemical equation: _____Pb(NO3)2  _____PbO + _____NO2 + _____O2 Then identify it’s type with a S, D, SR, DR, or C. Pick up 2 handouts when done. Objective – Driving forces Assignment: Driving forces worksheet 1 Agenda Mastery Quiz and P3 question Homework Review (types) Types of driving forces Precipitation reactions Solubility rules WB Word Equation practice Get out your reaction classifications for a HMK check.

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 thanne driving force. But if it has none, it will not happen.

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

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.

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+

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

Summary Solubility Rules

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 replacement reactions between ionic compounds. If all substances are aqueous, 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

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)

Exit Slip - Homework What’s Next? (How to prepare for the next day) Exit Slip: Determine the state descriptors for: NaOH CaO AgClO3 AgCl What’s Due? (Pending assignments to complete.) Start the Driving Forces Worksheet (Pages 1 and 3. On pg 3 only determine type and balance. ) What’s Next? (How to prepare for the next day) Read p473, p286-288, p548-549, p280-282