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Predicting Reactions

Predicting Reactions. Presented by Mr. Mark Langella STANYS 2006 PWISTA.com 11/7/06. Why do the reactions occur?. Gibbs Free Energy drives the Spontaneous reactions Lower PE energy Formation of Stronger Bonds Greater Entropy ( Formation of Gases) Solubility Formation Constant

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Predicting Reactions

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  1. Predicting Reactions Presented by Mr. Mark Langella STANYS 2006 PWISTA.com 11/7/06

  2. Why do the reactions occur? • Gibbs Free Energy drives the Spontaneous reactions • Lower PE energy • Formation of Stronger Bonds • Greater Entropy ( Formation of Gases) • Solubility • Formation Constant • Lose Yourself in Chemical Reactions - Google Video

  3. Synthesis or Combination Reactions • In synthesis or combination reactions, two or more substances combine together to form a single product. • The general form is A + B C • The products must contain only those elements found in the reactants.

  4. Metal + Nonmetal Salt • Magnesium ribbon is burned in oxygen

  5. Combination or Synthesis Reactions • General form • A + B C • In this demonstration • 2 Mg + O2 MgO • 3 Mg + N2 Mg3N2 • The oxygen and nitrogen occur naturally in the atmosphere • O2 is 21% of air • N2 is 78% of air

  6. Energy • Two types of energy are produced in this demonstration • heat energy DHf MgO = -601.83 kJ/mole (kiloJoules per mole) • this is said to be the ‘heat of formation’ for MgO • the negative sign indicates the formation is exothermic • light energy • approximately 10% of the energy of combustion occurs as light in this demonstration • more light than any other known reaction

  7. Online Demos • Reaction of Iron and Sulfur • http://www.pc.chemie.uni-siegen.de/pci/versuche/pics/anim/fes.mpg • Fe + S FeS • Reaction of Potassium and Oxygen • http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/page08.htm • Reaction of Lithium and Oxygen • http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/page02.htm • Reaction of Lithium and Chlorine • http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/page04.htm • Reaction of Sodium and Oxygen • http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/page05.htm • Reaction of Zinc and Sulfur • http://boyles.sdsmt.edu/znsulf/zincsul.htm

  8. Nonmetal + Nonmetal Molecular compounds • Reaction of Hydrogen and Oxygen • http://www.chem.uiuc.edu/clcwebsite/video/Bal2.mov

  9. Reaction of Phosphorus and Chlorine • http://boyles.sdsmt.edu/pwithcl/DirksTwo.asx • P4(s) + 10 Cl2(g) 4 PCl5(s) • Oxidation Number Changes

  10. Nonmetal Oxide + Water Oxyacid • Oxy Acid= Contains H+ ions attached to common Polyatomic ion of Nonmetal Oxide plus one more oxygen

  11. Formation of Carbonic Acid • Carbon dioxide and Water- Carbon Dioxide is easily produced by the reaction of sodium bicarbonate and vinegar. • http://boyles.sdsmt.edu/respira/AlexanderCo2Blue.asx

  12. Reaction of Carbon Dioxide and Limewater • http://boyles.sdsmt.edu/respira/AlexanderCo2White.asx • CO2(g) + Ca(OH)2(l)  CaCO3(s) + H2O(l)

  13. Metal oxide + water metal hydroxideEgg Fry

  14. DECOMPOSITION REACTIONS • Substances break down by means of decomposition reactions • The general form of a decomposition reaction is • C A + B • Decomposition reactions are the opposite of combination or synthesis reactions

  15. Decomposition of Metal Carbonate • Heating a metal carbonate always yields the metal oxide and carbon dioxide. • MCO3 MO + CO2 • Heating the carbonates • Most carbonates tend to decompose on heating to give the metal oxide and carbon dioxde. • For example, a typical Group 2 carbonate like calcium carbonate decomposes like this: • In Group 1, lithium carbonate behaves in the same way - producing lithium oxide and carbon dioxide. • The rest of the Group 1 carbonates don't decompose at Bunsen temperatures, although at higher temperatures they will. The decomposition temperatures again increase as you go down the Group.

  16. Metal Hydrogen Carbonate Decomposition • Heating a metal bicarbonate gives the metal oxide, carbon dioxide, and water. • MHCO3 MO + H2O + CO2 • Solid Sodium Hydrogen Carbonate is strongly heated

  17. Metal Chlorate Decomposition • Heating a metal chlorate gives the metal chloride plus oxygen. • MClO3 MCl + O2 • Burning Gummi Bears • http://www.webct.com/service/ViewContent?contentID=1249557&communityID=858&categoryID=1249537&sIndex=0 • Logger Pro Analysis

  18. Decomposition of Ammonium Dichromate • http://boyles.sdsmt.edu/dichrom/AmmoniumDichromate.asx • (NH4)2Cr2O7(s)  Cr2O3(s) + N2(g) + 4H2O(g)

  19. Peroxide Decomposition • Elephant’s Toothpaste • Website: • http://boyles.sdsmt.edu/tpaste/Cain.asx • Genie in a Bottle Demo • Website: http://boyles.sdsmt.edu/geniebot/genie.htm

  20. Reactions Based on Reduction Potentials EMF Potential • Reduction and Oxidation • Single replacement

  21. Cation Replacement • There are two types of single replacement reactions, in one, a metal or hydrogen replaces a positive ion • M0 + A+B- M+B- + A0

  22. Reaction of Sodium and Water http://boyles.sdsmt.edu/sodwat/SodiumWater.asx http://www.theodoregray.com/PeriodicTable/Stories/011.2/Videos/SodiumResearch03.html http://www.theodoregray.com/PeriodicTable/Stories/011.2/Videos/SodiumResearch02.html Sodium(s) + Water(l)  Sodium Hydroxide(aq) + Hydrogen(g) • 2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)

  23. Reaction of Potassium and Water • http://www.chem.shef.ac.uk/webelements-moov/K_H2O.mov • http://www.theodoregray.com/PeriodicTable/AlkaliBangs/019_K_doghowls.html • Potassium(s) + Water(l)  Potassium Hydroxide(aq) + Hydrogen(g) • 2K(s) + 2H2O  2KOH + H2(g) • Group I with water video • http://video.google.com/videoplay?docid=-2134266654801392897&q=rubidium+water

  24. Reaction of Zinc and Tin (II) Chloride • http://www.chemtopics.com/lectures/unit02/lecture1/displace.htm • Zinc(s) + Tin (II) Chloride(aq)  Tin(s) + Zinc (II) Chloride(aq) • Zn(s) + SnCl2(aq)  Sn(s) + ZnCl2(aq) • Zinc(s) + Hydrochloric Acid(aq)  Zinc (II) Chloride(aq) + H2(g) • Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g) • Aluminum and Copper ( II) Chloride

  25. Thermite Reaction • 2Al(s)+Fe2O3(s) Al2O3(s)+2Fe(l) • http://boyles.sdsmt.edu/thermite/ThirstrupThermiteClose.asx • http://www2.chemie.uni-erlangen.de/education/medprak/videos/thermit_v.mpg • http://video.google.com/videoplay?docid=-7231843493488769585&q=Reactions&hl=en

  26. Aqueous Redox ReactionsOxidation States of Manganese • Procedure • Add 30 ml of a .01 M KMnO4 solution to four small flasks labeled A , B, N ( Place Tablet 1/10 ml water) • To Flask A, Add 10 ml of 3M H2SO4 • MnO4- + H+ • To Flask B, add 10 ml of 5 M NaOH. • MnO4- + OH- • To Flask N add nothing. • MnO4-

  27. Watch the color changes • To Flask A add .01M NaHSO3 ( Tablet 2) slowly till you get a colorless Mn2+ ion. • MnO4- + 5H++ HSO3- 3H2O + 2Mn2+ + 5SO42- • To Flask N add .01M NaHSO3 ( Tablet 2)until a brown precipitate forms. • 2MnO4- + 3HSO3- 3SO42- + H++ H2O +MnO2 • To Flask B slowly add .01M NaHSO3 ( Tablet 2) until a green solution forms. • 2MnO4- + OH-+ HSO3- 2MnO42- + 2H2O + SO42-

  28. The Amazing Purple Drop • Oil Drop Demo • I2 + H20 HOI ( aq) + HI ( aq) • Meanwhile • I2 + 2e- = 2I-, Eo = 0.54 v • HCHO + 2H+ + 2e- = CH3OH, Eo = 0.19 v

  29. Reactions Driven by • Solubility and Precipitation • Formation of Gases ( Increase in entropy) • Formation of Water • Coordinate Covalent Bond Formation ( Lewis Acid-Base) • Formation Constants

  30. Formation of Water • Metal Oxide + an Acid Salt + Water • Metal Hydroxide + an Acid Salt + Water • (a special type of reaction called neutralization) • Milk of Magnesia Demo

  31. PREDICTIONS BASED ON SOLUBILITY • If one or both of the products in the double replacement reaction is insoluble in water, the reaction will occur. • Reaction #1 • Lead Nitrate and Sodium Chromate • Pb(NO3)2 (aq) + Na2CrO4 (aq)  PbCrO4 (s) + Na NO3(aq) • Pb 2+ + CrO42-  PbCrO4 (s) • Reaction # 2 • Silver Nitrate and Hydrochloric Acid • AgNO3(aq) + HCl(aq)  AgCl (s) + HNO3 (aq)

  32. SOLUBILITY RULES FOR COMMON IONIC COMPOUNDS IN WATER • 1. All nitrates, chlorates, and acetates are soluble in water. Silver acetate is sparingly soluble. • 2. Most common acids are soluble in water. • 3. All common IA, and ammonium compounds are soluble in water. • 4. All chlorides, bromides, and iodides are soluble in water except silver, mercury (I), and lead. HgI2 and HgBr2 are insoluble in water. • 5. All sulfates are soluble in water except CaSO4, SrSO4, BaSO4, PbSO4, Hg2SO4. Ag2SO4 is sparingly soluble in water. • 6. All carbonates, phosphates, oxides, and sulfites are insoluble in water but soluble in dilute acids except the IA and ammonium compounds. • 7. The sulfides of all metals are insoluble in water except the IA, IIA, and ammonium sulfides. • 8. All hydroxides are insoluble in water except the IA, Ca(OH)2, Sr(OH)2, and Ba(OH)2 hydroxides.

  33. Combustion • Whoosh Bottle • Rocket Explosions • Dynamite Soap Mixtures • Repeating Exploding Flask

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