1. Chapter 4; Reactions in Aqueous Solutions I.Electrolytes vs. NonElectrolytes II.Precipitation Reaction a)Solubility Rules

2. 4.1 A solution is a homogenous mixture of 2 or more substances The solute is(are) the substance(s) present in the smaller amount(s) The solvent is the substance present in the larger amount In aqueous solutions (aq) *solvent is water *solute can be ionic compounds, aqueous acids, bases, or molecular compounds

3. An electrolyte is a substance that, when dissolved in water, results in a solution that can conduct electricity. A nonelectrolyte is a substance that, when dissolved, results in a solution that does not conduct electricity. nonelectrolyteweak electrolytestrong electrolyte 4.1

4. Soluble Salts - substances which result from the neutralization of an acid by a base and are soluble in water are of interest - since they dissociate in water to give separate ions NaCl(aq)  Na + (aq) + Cl - (aq) CaCl 2(aq)  Ca 2+ (aq) + 2 Cl - (aq) C 12 H 22 O 11(aq)  C 12 H 22 O 11 (aq) molecules stay intact - nonelectrolyte

5. **The formation of an insoluble solid (a precipitate) drives a chemical reaction. **For these reactions we can write three kinds of equations. MOLECULAR, IONIC, AND NET IONIC EQUATIONS a) Molecular Equations-complete formulas are written for all the reactants and products, no ions are written. b) Ionic equations-all strongly soluble electrolytes are written in their dissociated (ionized) forms.

6. c) Net Ionic equations-only involve those chemical species which are involved in a chemical reaction. All spectator ions are eliminated. Spectator ions-those ions which do not participate in the chemical reaction but are present in the reaction mixture. Write the molecular, ionic, and net ionic equations for the reaction of an aqueous solution of CaCl 2 and an aqueous solution of Na 2 CO 3.

7. 4.1 Strong Electrolyte Weak ElectrolyteNonelectrolyte Strong AcidsWeak AcidsMolecular Compounds Strong BasesWeak Bases Ionic Compounds

8. Electrolytic Solutions Contain Mobile Cations (+) and Anions(-) Ionic Compounds, Aqueous Acids, and Base Dissociate Into the Ions They are Made of When Dissolved in Water. NaCl (s)  Na + (aq) + Cl - (aq) More Ions in Solutions; Stronger Electrolyte H2OH2O

9. Strong Electrolyte – 100% dissociation HCl (g) H + (aq) + Cl - (aq) H2OH2O Weak Electrolyte – not completely dissociated Weak vs. Strong Electrolyte A strong electrolyte will produce more ions when same amount of solid is dissolved in solvent. HNO 2 NO 2 - (aq) + H + (aq) H2OH2O H+H+ Cl - H+H+ H+H+ NO 2 - H+H+

10. Precipitation Reactions Mix two aqueous solutions made by dissolving ionic compounds in water. If a reaction happens, a precipitate (solid) is formed.

12. Predicting Products of Precipitation Reactions 1)Ionic Compounds are Strong Electrolytes –Determine charge on all ions of reactants 2)Using Ion Charges; Predict formula of products. ( + ion of one reactant forms compound with – ion of other reactant) 3)Balance Equation 4)Determine is product is solid or aqueous solution

13. Solubility Rules for Common Ionic Compounds In water at 25 0 C Soluble CompoundsExceptions Compounds containing alkali metal ions and NH 4 + NO 3 -, HCO 3 -, ClO 3 - Cl -, Br -, I - Halides of Ag +, Hg 2 2+, Pb 2+ SO 4 2- Sulfates of Ag +, Ca 2+, Sr 2+, Ba 2+, Hg 2+, Pb 2+ Insoluble CompoundsExceptions CO 3 2-, PO 4 3-, CrO 4 2-, S 2- Compounds containing alkali metal ions and NH 4 + OH - Compounds containing alkali metal ions and Ba 2+ 4.2

14. Predicting Products of Precipitation Reactions (Cont) 5)Determine spectator ions (Ions that are still dissolved in water in the product) 6)Write net ionic equation (Only shows ions involved in forming solid)

15. 1) the molecular equation is: CaCl 2(aq) + Na 2 CO 3(aq)  CaCO 3(s) +2NaCl (aq) 2) the ionic equation is: Ca 2+ (aq) + 2 Cl - (aq) + 2 Na + (aq) + CO 3 2- (aq)  CaCO 3(s) + 2 Na + (aq) + 2 Cl - (aq) 3) the net ionic equation is: Ca 2+ (aq) + CO 3 2- (aq)  CaCO 3(s)

16. Precipitation Reactions Precipitate – insoluble solid that separates from solution molecular equation ionic equation net ionic equation Pb 2+ + 2NO 3 - + 2Na + + 2I - PbI 2 (s) + 2Na + + 2NO 3 - Na + and NO 3 - are spectator ions PbI 2 Pb(NO 3 ) 2 (aq) + 2NaI (aq) PbI 2 (s) + 2NaNO 3 (aq) precipitate Pb 2+ + 2I - PbI 2 (s) 4.2

17. AgNO 3 (aq) + NaCl (aq) AgCl (s) + NaNO 3 (aq) Ag + + NO 3 - + Na + + Cl - AgCl (s) + Na + + NO 3 - Ag + + Cl - AgCl (s) 4.2 Write the net ionic equation for the reaction of silver nitrate with sodium chloride.