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Chemistry 100(02) Fall 2013

Chemistry 100(02) Fall 2013. Instructor: Dr. Upali Siriwardane e-mail : upali@coes.latech.edu Office : CTH 311 Phone 257-4941 Office Hours : M,W, 8:00-9:30 & 11:30-12:30 a.m Tu,Th,F 8 :00 - 10:00 a.m.   Or by appointment Test Dates :.

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Chemistry 100(02) Fall 2013

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  1. Chemistry 100(02) Fall 2013 Instructor: Dr. UpaliSiriwardane e-mail: upali@coes.latech.edu Office: CTH 311 Phone257-4941 Office Hours: M,W, 8:00-9:30 & 11:30-12:30 a.m Tu,Th,F8:00 - 10:00 a.m.   Or by appointment Test Dates: September 30, 2013 (Test 1): Chapter 1 & 2 October 21, 2013 (Test 2): Chapter 3 & 4 November 13, 2013 (Test 3) Chapter 5 & 6 November 14, 2013 (Make-up test) comprehensive: Chapters 1-6 9:30-10:45:15 AM, CTH 328

  2. REQUIRED: Textbook:Principles of Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro - Pearson Prentice Hall and also purchase the Mastering Chemistry Group Homework, Slides and Exam review guides and sample exam questions are available online: http://moodle.latech.edu/ and follow the course information links. OPTIONAL: Study Guide: Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro 2nd Edition Student Solutions Manual: Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro2nd Text Book & Resources

  3. Chapter 4. Chemical Quantities and Aqueous Reactions 4.1 Global Warming and the Combustion of Fossil Fuels…………………. 127 4.2 Reaction Stoichiometry: How Much Carbon Dioxide?......................... 128 4.3 Limiting Reactant, Theoretical Yield, and Percent Yield………………. 133 4.4 Solution Concentration and Solution Stoichiometry………………….. 140 4.5 Types of Aqueous Solutions and Solubility…………………………….. 146 4.6 Precipitation Reactions………………………………………………….. 150 4.7 Representing Aqueous Reactions: Molecular, Ionic, and Complete Ionic Equations…………………………………………………………………........ 153 4.8 Acid–Base and Gas-Evolution Reactions……………………………..... 155 4.9 Oxidation–Reduction Reactions…………………………………………. 162

  4. Chapter 4.Chemical Quantities and Aqueous Reactions

  5. Why Solution Chemistry? Collisions of reactants decides the rates of a reactions Why not gaseous Reactions? In Gases: Very fast Reactions (burning natural gas) Solution reactions are manageable! Liquids: Fast Reactions (precipitation of AgCl) Water is the most common solvent Why not solid Reactions? Solids: Very slow Reactions (making ceramics)

  6. 1) Identify the gas phase, solution (liquid) and solid phase reactions. a) O2(g) + 2 H2(g) 2 H2O(l): b) AgNO3(aq) + NaCl(aq) AgCl(s) insoluble salt + NaNO3(aq) c) 2C4H10(g) + 13O2(g)  8CO2(g) + 10H2O(g): d) 2 Al (s) + Fe2O3 (s)  2 Fe(s) + Al2O3(s):

  7. What is a Solution? • A solution: A homogeneous mixture of two or more components. Sugar in water Oxygen in water Air Dental fillings Saline

  8. Dissolution of (a) Ionic and (b) Molecular Compounds

  9. Components of a SolutionSoluteSolvent • substance that is present in smallest quantity • dissolved substance(s) • can be either a gas, a liquid, or a solid • one or more present in a solution • substance present in largest quantity • only one per solution • water in aqueous solutions

  10. Concentration Units • Molarity (M) • b) Molality (m) • c) Mole fraction (a) d) Mass percent (% weight) e) Volume percent (% volume) f) "Proof" g) ppm and ppb M = m = a = w/w % = x 100 v/v % = x 100 Proof = (w/w %)x 2 ppm (w/w) = x 106 ppm (w/v) = x 106 ppb (w/w) = x 109

  11. Examples Calculate the molarity of a solution prepared by dissolving 200.0 g of K2SO4 in enough water to make 500.0 mL solution. moles of solute Molarity(M) = ---------------------- Liters of solution

  12. Preparing 1.00 L of a 1.00 M NaCl Solution from a Solid Solute

  13. 2) Molarity Calculations: Calculate the molarity of a solution prepared by dissolving 200.0 g of K2SO4 in enough water to make 500.0 mL solution.

  14. solute = K2SO4; F.W. = 174.27 g/mol; mass= 200g moles of K2SO4 = ? 200 g /174.27 g K2SO4 = 1.148 mol K2SO4 500.0 mL = ? Liters of solution = 0.5 L Molarity? 1.148 mol K2SO4 Molarity of K2SO4 sol. = ------------------------ 0.5 Liters of solution = 2.30 mole/Liter = 2.30 M (M = moles/liters)

  15. How do you calculate moles of substances in solutions • Use concentration of solution to convert L or mL of solution in to moles • What is concentration of a solution? • The relative amounts of solute and solvent • There are so many ways to show amount: g, mole, equivalents, volume

  16. 3) Gram-mol-M conversions: How many grams of KNO3 are contained in 500 mL of a 0.500 M solution of potassium nitrate?

  17. Dilution Problems Why we dilute solutions? Preparing solutions by adding water to concentrated solutions moles before = moles after MiVi = MfVf Mi = initial molarity Vi = initial volume Mf = final molarity Vf = final molarity

  18. Solution Preparation by Dilution

  19. 4) Dilution problems: How many mL of 2.00 M solution of nitric acid, HNO3 are required with water to make a 250 mL of 1.50 M HNO3 acid solution?

  20. 5) What is concentration of Cl- in 0.4 M MgCl2 aqueous solution if MgCl2 a strong electrolyte? Ion Concentrations in Solutions

  21. Types of Chemical Reactions Based on driving force a) Precipitation Reactions (insoluble salt) b)Acid-base Reactions (neutralization) c)Gas-formingReactions (escaping gas) d)Oxidation-reduction (REDOX)Reactions (electron transfer)

  22. 6) Classify following solution reactions as precipitation, acid/base and redox reactions. • KOH (aq) + HNO3(aq) --> KNO3(aq) + H2O(l): b) HCl(aq) + NaHCO3(aq) --> NaCl(aq) + H2O(l) + CO2(g): c) Fe(s) + Cu(NO3)2(aq) --> Fe(NO3)2(aq) + Cu(s) d) AgNO3(aq) + NaCl(aq) --> AgCl(s) + NaNO3(aq) e) NaOH(aq) + HC2H3O2(aq) --> NaC2H3O2(aq) + H2O(l)

  23. Some acids, bases and their salts Acid Sodium salt Name Formula Name Formula Acetic acid HC2H3O2 Sodium acetate NaC2H3O2 Hydrogen chloride HCl Sodium chloride NaCl Nitric acid HNO3 Sodium nitrate NaNO3 Phosphoric acid H3PO4 Sodium phosphate Na3PO4 Sulfuric acid H2SO4 Sodium sulfate Na2SO4 Base Chloride salt Name FormulaName Formula Sodium hydroxide NaOH Sodium chloride NaCl Barium oxide BaO Barium chloride BaCl2 Sodium oxide Na2O Sodium chloride NaCl Ammonia NH3 Ammonium chloride NH4Cl

  24. 7) Identify molecular compounds, acids, bases, and salts among the following: a) AgNO3 b) NaCl c) C6H12O6 d) H3PO4 e) NaOH f) HCl, g) NaNO3 h ) CH3OH i) CH3COOH j) H2SO4 k) HC2H3O2 l) KNO3 m) HNO3 n) MgO o) K2O p) SO3

  25. How do find precursor Acid and base of a Salt Acid (A) + Base(B) = Salt + water (H2O) HA + BOH = BA + H2O E.g. LiNO3 B (Li) A (NO3) OH H BOH(LiOH) HA(HNO3)

  26. 8) Identify the precursor acid and base for the following salts: a) AgNO3 b) NaCl c) NaNO3 d) K2SO4, e) NaC2H3O2

  27. Types of Chemical Equations Molecular equation: Equation with formula, correct stoichiometric coefficients and physical form written within parenthesis. Ionic equation: All the ionic compounds soluble in water are separated into ions written with their ionic charge and (aq). Net Ionic equation: Ionic equation with all spectator ions removed from both sides.

  28. Chemical Reaction: NaCl(aq)+AgNO3(aq) -->AgCl(s)+ NaNO3(aq) Molecular equation: NaCl (aq) + AgNO3 (aq) --> AgCl (s) + NaNO3 (aq) Ionic Equation: Na+ (aq) + Cl-(aq) + Ag+ (aq) + NO3-(aq) --> AgCl(s) + Na+(aq) + NO3- (aq) Spectator Ions: Na+ (aq) and NO-3 (aq) Net Ionic Equation: Cl- (aq) + Ag+ (aq) --> AgCl (s)

  29. Spectator Ions Ions appearing on both side of an ionic equation. We need to look at the ionic equation: Ionic Equation: Na+ (aq) + Cl-(aq) + Ag +(aq) + NO3-(aq)--> AgCl(s) + Na +(aq) + NO3-(aq)

  30. Ionic equations H2O H2O When ionic substances dissolve in water, they dissociate into ions. AgNO3 Ag++ NO3- KClK+ + Cl- When a reaction occurs, only some of the ions are actually involved in the reaction. Ag++ NO3- +K+ + Cl-AgCl(s) + K+ + NO3-

  31. Write molecular equation etc… 9) Write molecular, total ionic, and net ionic reactions for the following solution reactions a) Ba(NO3)2(aq) + Na2SO4(aq) ----> BaSO4(s) + 2NaNO3 (aq) Molecular equation: Total ionic equation: Spectator Ions: Net ionic equation:

  32. 9) Write molecular, total ionic, and net ionic reactions for the following solution reactions b) HCl(aq) + NaOH(aq) ----> NaCl(aq) + H2O(l) Molecular equation: Total ionic equation: Spectator Ions: Net ionic equation:

  33. 9) Write molecular, total ionic, and net ionic reactions for the following solution reactions c) NaOH(aq) + HC2H3O2(l) ----> NaC2H3O2(aq) + H2O(l) Molecular equation: Total ionic equation: Spectator Ions: Net ionic equation:

  34. Precipitation reactions They are double displacement reactions of ionic compounds where an insoluble salt is formed when two aqueous salt solutions are mixed. • Ba(NO3)2(aq) + Na2SO4(aq) ----> BaSO4 (s) + 2NaNO3 (aq) • NaCl(aq)+AgNO3(aq) -->AgCl(s)+ NaNO3(aq)

  35. Precipitation of Barium Sulfate Double Displacement: Formation of insoluble salt is the diving force BaCl2(aq) + Na2SO4(aq)  2NaCl(aq) + BaSO4(s) precipitate

  36. Precipitation of Silver Chloride Formation of insoluble salt is the diving force AgNO3 (aq) + NaClAgCl(s) + NaNO3 (aq) precipitate

  37. Solubility rules for ionic compounds • All acids are soluble. • All Na+, K+ and NH4+salts are soluble. • All nitrate and acetate salts are soluble. • All chlorides except AgCl and Hg2Cl2 PbCl2 are soluble. • All sulfates are soluble exceptPbSO4, Hg2SO4, SrSO4 and BaSO4. • All sulfides are insoluble except those of the Group IA (1), IIA (2) and ammonium sulfide. • All hydroxides are insoluble except those of the group IA(1) and IIA Ba(OH)2. Sr(OH)2 and Ca(OH)2

  38. Illustration of SomeSolubility Rules

  39. 10) Which of the following salts (ionic compounds) is soluble/insoluble in water? • NaCl b) Li2CO3 c) AgCl d) PbBr2 • NH4NO3 f) Ca(NO3)2 g) CaSO4h) CaCO3 i) Mg3(PO4)2 j) MnO2 k) Al(OH)3 l) BaSO4 m) CH3CO2Na n) Cu(OH)2 o) Fe(ClO4)2

  40. Precipitation or Not • MgI2 + NaNO3= 2 NaI + Mg(NO3)2 • Ba(NO3)2+Na2SO4= BaSO4 + 2 NaNO3 • AgCl +NaNO3 = AgNO3 + NaCl

  41. Acid/base Reactions Acid • substance that donates H+ ions to solution • sour-tasting substances • substances whose aqueous solutions are capable of turning blue litmus indicators red • dissolves certain metals to form salts • react with bases or alkalis to form salts • substance that donates a OH-1 ion to solution • hydroxides and oxides of metals • bitter tasting, slippery solutions • turn litmus blue • react with acids to form salts Base

  42. Neutralization Reactions Formation of water is the diving force acid + base  “salt” + water HCl + NaOHNaCl + H2O H2SO4 + 2KOH  K2SO4 + 2H2O Salt • Substances produced by the reaction of an acid with a base • Characterized by ionic bonds and high melting points • Electrical conductivity when melted or when in solution • Has a crystalline structure when in the solid state

  43. Ionization of Acids in Water

  44. Titrations

  45. Ionic Equations Strong Acid/base Molecular Equation: HCl(aq) + NaOH(aq) ----> NaCl(aq) + H2O(l) Total Ionic Equation: H+ + Cl-1 + Na+ + OH-1  Na+ +Cl-1 + H2O Net Ionic Equation: H+ + OH-1  H2O NaOH(aq) + HC2H3O2(aq) -----> NaC2H3O2(aq) + H2O(l) Na+(aq) + OH -(aq) + HC2H3O2(aq) -----> Na+(aq) +C2H3O2-(aq) + H2O(l) HC2H3O2(aq) + OH-1 C2H3O2-(aq) + H2O

  46. Common Acids and Bases

  47. Gas-Forming Exchange Reaction: CO2, SO2, H2SEscape of a gas is the diving force

  48. Gas-Forming Reactions Metal carbonates + acid  CO2(g) + salt + water Na2CO3(aq) + 2HCl(aq)  H2O(l) + CO2(g) + 2 NaCl(aq) Net ionic: CO32- + 2 H+ H2O(l) + CO2(g) CaCO3(s) + 2 HCl(aq)  CO2(g)+ H2O(l) + CaCl2(aq) Net ionic: CaCO3(s) + 2 H+ CO2(g)+ H2O(l) + Ca2+ Metal (s) + acid  Gas + salt Mg(s)+ 2 HCl(aq)  H2(g) + MgCl2(aq) Net ionic: Mg(s) + 2 H+ H2(g) + Mg2+

  49. Reaction of Metal Carbonates with Acids Molecular Equation: CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2CO3(aq) H2CO3(aq) H2O +CO2(g) Total Ionic Equation: CaCO3(s) + 2H+ + 2Cl-1 Ca+2 + 2Cl-1 + H2O + CO2(g) Net Ionic Equation: CaCO3(s) + 2H+ Ca+2 + H2O + CO2(g)

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