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Entry Task: Sept 12 -13 th Block 2

Entry Task: Sept 12 -13 th Block 2 . Question: Which of the following is insoluble? MgF 2, AgCl , Na 2 SO 4 You have 5 minutes. Chapter 4; Reactions in Aqueous Solutions. Sec 4.1 Properties of Aqueous Solutions What is an electrolyte? Ionic compounds in water.

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Entry Task: Sept 12 -13 th Block 2

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  1. Entry Task: Sept 12 -13th Block 2 Question: Which of the following is insoluble? MgF2, AgCl, Na2SO4 You have 5 minutes

  2. Chapter 4; Reactions in Aqueous Solutions • Sec 4.1 Properties of Aqueous Solutions • What is an electrolyte? • Ionic compounds in water. • Molecular compounds in water • Exercises: 5 & 6

  3. 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 4.1

  4. Ionic compounds in water: • Dissociate into its component ions.

  5. http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/thermochem/solutionSalt.htmlhttp://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/thermochem/solutionSalt.html

  6. nonelectrolyte weak electrolyte strong electrolyte 4.1 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.

  7. Strong Electrolytes • Exists in solution completely or almost completely as ions. • All ionic compounds and a few molecular compounds.(Ex: Strong Acids) The arrow in one directions means there is no tendency of the ions to recombine, they fully or nearly fully ionize.

  8. Weak Electrolytes • Molecular compounds that produce a small concentration of ions when dissolved in H2O. Ex: Acetic acid (HC2H3O2) only slightly ionizes when dissolved in water. HC2H3O2(aq)H+(aq)+ C2H3O2-(aq) Weak acids are better conductors if they are dilute, as you will see in lab. Explain.

  9. Weak Electrolytes Ex: Acetic acid (HC2H3O2) only slightly ionizes when dissolved in water. HC2H3O2(aq)H+(aq)+ C2H3O2-(aq) Arrows in both directions means that the Chemical equilibrium results in ions forming at the same rate that molecules recombine.

  10. Weak vs. Strong Electrolyte A strong electrolyte will produce more ions when same amount of solid is dissolved in solvent. H+ Cl- Cl- NO2- H+ H2O HNO2 NO2- (aq) + H+ (aq) Strong Electrolyte – 100% dissociation HCl (g) H+ (aq) + Cl- (aq) H2O Weak Electrolyte – not completely dissociated NO2- H+ H+

  11. 4 Types of Inorganic Compounds • Ionic; Made of + and – ions. Generally + ions are from metal and – ions from nonmetals. • Molecular; Made of 2 or more Nonmetals • Aqueous Acid; H+ and – ion dissolved in water. Generally – ions are nonmetal • Bases; + ion; - ions are hydroxide (OH)-

  12. Cl- Na+ All ionic compound will form ions when dissolved in water except molecular compounds (acids are the exceptions) • Ionic Compounds • Na Cl (aq) 2. Bases Na (OH) (aq) Na+ OH- 3. Aqueous Acids HCl (aq) 4. Molecular ICl (aq) NO Ions! Cl- H+ I Cl

  13. Do not get to wrapped up in the difference between the terms ionization and dissociation. Consider them to mean the same thing, the separation of a substances ions. Equations showing ionization or dissociation

  14. 4.6 answers 6a. CuBr2 Cu+2 + 2Br- 6b. Na2CO3 Na+ + CO3-2 2 6c. HClO4 H+ + ClO4- 6d. (NH4)2SO4 NH4+ + SO4-2 2

  15. Chapter 4; Reactions in Aqueous Solutions • Sec 4.2 Precipitation rxns • pptrxns • Solubility rules- KNOW THESE!! • Dbl. Replacement Rxns • ppt formed • insoluble or slightly soluble product • gas evolved • NH3, CO2, SO2, H2S • molecule formed • weak electrolyte or nonelectrolyte • Ionic Equations • Complete or overall ionic • Net ionic • Spectator ions • EXErcises: 9 & 10, 11 & 12, 13&14,

  16. Precipitation Reactions • Reactions that result in an insoluble product (precipitate). • Insoluble: • Substance with solubility less than 0.01 mol/L • Water molecules cannot overcome the attraction between the ions.

  17. Exchange Reactions • Metathesis reactions • Double displacement • Double replacement

  18. KI (aq) + Pb(NO3)2 (aq)  PbI2(s) + KNO3 (aq) Precipitate

  19. You must be able to determine whether a substance is soluble in water by simple examination of the chemical formula. To do so, you must memorize how specific polyatomic ions act in water. Not as hard as it sounds. We will focus mainly on 10 anions. This will give you the tools to predict the solubility of many compounds.

  20. Solubility of Ionic Compounds • All acetates and nitrates are soluble in water. • All ionic compounds of alkali metals and ammonium are soluble. • Table on next slide is on page 111 of your textbook.

  21. Soluble Exceptions Ag+, Hg22+, Pb2+ None Ag+, Hg22+, Pb2+ Ag+, Hg22+, Pb2+ None Sr2+, Ba2+, Hg22+, Pb2+ Cl- Acetate ion C2H3O2- Br- I- NO3- SO42-

  22. Insoluble Exceptions NH4+ and Group 1 metals Group 1 metals and Ba2+, Sr2+, Ca2+ NH4+ and Group 1 metals NH4+ and Group 1 metals and Ba2+, Sr2+, Ca2+ CO32- OH- PO43- S2-

  23. Predict- Is it soluble? SrCO3 Soluble soluble AgCl Soluble NaSO4 Soluble (NH4)2SO4 Ba3(PO4)2 Insoluble Insoluble PbSO4 Soluble NiCl2 Soluble KNO3 Insoluble Ag2S Insoluble CaCO3 Soluble Cs3PO4

  24. 4.10- Predict soluble or insoluble Soluble K3PO4 Soluble Pb(C2H3O2)2 Ga(OH)3 Insoluble Soluble NaCN BaSO4 Insoluble

  25. Predict the products by switching the cations. Which will precipitate? BaSO4 + 2KCl (s) (aq) BaCl2(aq) + K2SO4(aq) Predict which will be the precipitate? Fe2(SO4)3(aq) + 6LiOH (aq) 2Fe(OH)3 + 3Li2SO4 (s) (aq) Predict which will be the precipitate? Ba(NO3)2(aq) + 2KOH (aq) Ba(OH)2 + 2KNO3 (aq) (aq) Predict which will be the precipitate?

  26. 4.12 Hg2I2 + 2KNO3 (aq) (s) Hg2(NO3)2(aq) + 2KI(aq) Predict which will be the precipitate? (NH4)2CO3(aq) + CaCl2(aq) 2NH4Cl + CaCO3 (aq) (s) Predict which will be the precipitate? 2NaC2H3O2(aq)+ CuSO4(aq) Na2SO4 + Cu(C2H3O2)2 (aq) (aq) Predict which will be the precipitate?

  27. Equation Types • Molecular • Complete Ionic • Net ionic equation 3

  28. Ionic Equations • Those ions that appear on both sides of a complete ionic equation are known as Spectator Ions. • These ions are still in solution. • Net ionic equations do not include spectator ions.

  29. Writing Net Ionic Equations • Write a balanced molecular equation. • Rewrite the equation showing ions of strong electrolytes only. • Identify and cancel all spectator ions.

  30. precipitate Pb2+ + 2NO3- + 2Na+ + 2I- PbI2 (s) + 2Na+ + 2NO3- Pb2+ + 2I- PbI2 (s) PbI2 Precipitation Reactions Precipitate – insoluble solid that separates from solution Pb(NO3)2(aq) + 2NaI (aq) PbI2(s) + 2NaNO3(aq) molecular equation ionic equation net ionic equation Na+ and NO3- are spectator ions

  31. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Write the net ionic equation for the reaction of silver nitrate with sodium chloride. Ag+ + NO3- + Na+ + Cl- AgCl (s) + Na+ + NO3- Ag+ + Cl- AgCl (s)

  32. 4.13 MgCO3 + Na2SO4 (s) (aq) Predict which will be the precipitate? Na2CO3(aq) + MgSO4(aq) Write ionic equation 2Na+1(aq)+ CO3-2(aq) + Mg+2(aq) + SO4-2(aq) MgCO3 (s) + 2Na+1(aq) + SO4-2(aq) Write the net ionic equation Mg+2(aq) + CO3-2(aq) MgCO3 (s)

  33. 4.13 PbS + 2NaNO3 (aq) (s) Predict which will be the precipitate? Pb(NO3)2(aq) + Na2S (aq) Write ionic equation Pb+2(aq)+ 2NO3-1(aq) + 2Na+1(aq) + S-2(aq) PbS (s) + 2Na+1(aq) + 2NO3-1(aq) Write the net ionic equation Pb+2(aq) + S-2(aq) PbS(s)

  34. 4.13 6NH4Cl + Ca3(PO4)3 (aq) (aq) Predict which will be the precipitate? 2(NH4)3PO4(aq) + 3CaCl2(aq) Write ionic equation 6NH4+1(aq)+ 2PO4-3(aq) + 3Ca+2(aq) + 6Cl-1(aq) 6NH4+1 (aq) + 6Cl-1(aq) + 3Ca+1(aq)+PO4-3(aq) Write the net ionic equation No reaction

  35. 4.14 2NaNO3 + PbSO4 (aq) (s) Predict which will be the precipitate? Pb(NO3)2(aq) + Na2SO4(aq) Write ionic equation Pb+2(aq)+ 2NO3-1(aq) + 2Na+1(aq) + SO4-2(aq) PbSO4 (s) + 2Na+1(aq) + 2NO3-1(aq) Write the net ionic equation Pb+2(aq) + SO4-2(aq) PbSO4 (s)

  36. 4.14 Cu(OH)2 + 2NaBr (s) (aq) Predict which will be the precipitate? CuBr2(aq) + 2NaOH (aq) Write ionic equation Cu+2(aq)+ 2Br-1(aq) + 2Na+1(aq) + 2OH-1(aq) Cu(OH)2 (s) + 2Na+1(aq) + 2Br-1(aq) Write the net ionic equation Cu+2(aq) + 2OH-1(aq) Cu(OH)2 (s)

  37. 4.14 AgI + KNO3 (aq) (s) Predict which will be the precipitate? AgNO3(aq) + KI(aq) Write ionic equation Ag+1(aq)+ NO3-1(aq) + K+1(aq) + I-1(aq) AgI (s) + K+1(aq) + NO3-1(aq) Write the net ionic equation Ag+1(aq) + I-1(aq) AgI (s)

  38. For Tomorrow • Complete the “Basics of equation writing” handout. • Observing ionic reactions lab

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