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Reactions Involving Ions: Molecular vs. Ionic Equations

Reactions Involving Ions: Molecular vs. Ionic Equations. Chemical Reaction can be expressed by: Molecular Equation (balanced chemical equation) Complete Ionic Equation (showing all ions in reaction) Net Ionic Equation (showing only those ions directly involved in reaction) Consider

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Reactions Involving Ions: Molecular vs. Ionic Equations

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  1. Reactions Involving Ions:Molecular vs. Ionic Equations • Chemical Reaction can be expressed by: • Molecular Equation (balanced chemical equation) • Complete Ionic Equation (showing all ions in reaction) • Net Ionic Equation (showing only those ions directly involved in reaction) • Consider Copper (III) sulfate reacts with sodium hydroxide to form copper (III) hydroxide and sodium sulfate (all in water). • Express reaction in molecular, complete ionic, • and net ionic equations

  2. 8 Simple Rules For Common Ionic Compounds

  3. (Taken from Cornell University – Adapted by Daley – Sing to Rhythm of 99 Bottles)  Potassium, sodium, and ammonium salts,  Whatever they may be, Can always be depended on For solubility. Asked about the nitrates or acetates The answer is always clear, They each and all are soluble, Is all we want to hear.  Most every chloride's soluble At least we've always read Save silver, mercurous mercury And (slightly) chloride of lead. Take the Bromide and iodide salts There soluble as can be Save silver, mercury, and lead That precipitate as you see Every single sulfate Is soluble ,  'Tis said 'Cept barium and strontium And calcium and lead.  Song For Solubility!! Hydroxides of metals won't dissolve That is, all but three Potassium, sodium and ammonium Dissolve quite readily. And then you must remember That you must not "forgit" Calcium, barium, strontium Dissolve a little bit.  The carbonates are insoluble,  It's lucky that it's so, Or else, our marble buildings Would melt away like snow.  (Repeat with feeling)  Only note is that all Lithium salts are Soluble too!!!

  4. Predicting Whether a Precipitation Reaction Occurs; Writing Equations: a) Calcium Nitrate and Sodium Sulfate solutions are added together. Molecular Equation Ca(NO3)2 (aq) + Na2SO4 (aq) CaSO4 (s) + NaNO3 (aq) Total Ionic Equation Ca2+(aq)+2 NO3-(aq) + 2 Na+(aq)+ SO4-2(aq) CaSO4 (s) + 2 Na+(aq+) 2 NO3-(aq) Net Ionic Equation Ca2+(aq) + SO-4(aq) CaSO4 (s) Spectator Ions are Na+ and NO3- b) Ammonium Sulfate and Magnesium Chloride are added together. In exchanging ions, no precipitates will be formed, so there will be no chemical reactions occurring! All ions are spectator ions!

  5. Precipitation Reactions: Will a Precipitate Form? If we add a solution containing potassium chloride to a solution containing ammonium nitrate, will we get a precipitate? KCl(aq) + NH4NO3 (aq) = K+(aq) + Cl-(aq) + NH4+(aq) + NO3-(aq) By exchanging cations and anions we see that we could have potassium chloride and ammonium nitrate, or potassium nitrate and ammonium chloride. In looking at the solubility table it shows all possible products as soluble, so there is no net reaction! KCl(aq) + NH4NO3 (aq) = No Reaction! If we mix a solution of sodium sulfate with a solution of barium nitrate, will we get a precipitate? From the solubility table it shows that barium sulfate is insoluble, therefore we will get a precipitate! Na2SO4 (aq) + Ba(NO3)2 (aq) BaSO4 (s) + 2 NaNO3 (aq)

  6. Figure 4.6: Reaction of magnesium chloride and silver nitrate. Photo courtesy of American Color. Write molecular and ionic equations for this reaction. Ionic equation: Ag+(aq) + Cl-(aq) AgCl(s)

  7. Oxidation-Reduction 2Na (s) + Cl2(g) 2NaCl(s)

  8. Acid-Base

  9. Definition of Acid & Base • Arrhenius • Acid: substance that produces H+ ions • Base: substance that produces HO- ions • Bronsted & Lowry • Acid: substance that donates a proton to another substances • Base: substance that accepts a proton to another substances

  10. Acids - A Group of Covalent Molecules Which Lose Hydrogen Ions to Water Molecules in Solution When gaseous hydrogen iodide dissolves in water, the attraction of the oxygen atom of the water molecule for the hydrogen atom in HI is greater that the attraction of the of the iodide ion for the hydrogen atom, and it is lost to the water molecule to form an hydronium ion and an iodide ion in solution. We can write the hydrogen atom in solution as either H+(aq) or as H3O+(aq) they mean the same thing in solution. The presence of a hydrogen atom that is easily lost in solution is an “Acid” and is called an “acidic” solution. The water (H2O) could also be written above the arrow indicating that the solvent was water in which the HI was dissolved. HI(g) + H2O(L) H+(aq) + I -(aq) HI(g) + H2O(L) H3O+(aq) + I -(aq) H2O HI(g) H+(aq) + I -(aq)

  11. Figure 4.8B: Red cabbage juice added to solutions in the beakers.Photo courtesy of James Scherer.

  12. Molecular representation of ammonium hydroxide. NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

  13. Reaction of nitric acid with water. HNO3(aq)+ H2O(l)  NO3-(aq) + H3O+(aq)

  14. Beaker with Na+(aq), C2H302-(aq), and SrS04 (solid). Na2SO4 (aq)+ Sr(C2H3O2)2(aq)  SrSO4 (s)+ NaC2H3O2 (aq) SO4-2 (aq)+ Sr+2(aq) SrSO4 (s) 2 Na+(aq) + SO4-2 (aq)+ Sr+2(aq) + 2C2H3O2-(aq)  SrSO4 (s)+ 2 Na+(aq) + 2C2H3O2-(aq)

  15. Figure 4.9: Reaction of a carbonate with an acid.Photo courtesy of American Color.

  16. Figure 4.10: Iron nail and copper ( II) sulfate.Photo courtesy of American Color.

  17. Figure 4.10: Fe reacts with Cu2+(aq) and makesCu(s).Photo courtesy of American Color.

  18. Figure 4.10: The copper metal plates out on the nail.Photo courtesy of American Color. Write a net ionic equation for this reaction! Cu+2(aq) + Fe(s) Cu(s) + Fe+2(aq)

  19. Percent Yield/Limiting Reactant Problem - II N2 (g) + 3 H2 (g) 2 NH3 (g) Solution Cont. We have 3.066 moles of Nitrogen, and it is limiting, therefore the theoretical yield of ammonia is: 2 mol NH3 1 mol N2 3.066 mol N2 x = 6.132 mol NH3 (Theoretical Yield) 6.132 mol NH3 x = 104.427 g NH3 (Theoretical Yield) 17.03 g NH3 1 mol NH3 Actual Yield Theoretical Yield Percent Yield = x 100% 98.67 g NH3 104.427 g NH3 Percent Yield = x 100% = 94.49 %

  20. Molarity (Concentration of Solutions)= M Moles of Solute Moles Liters of Solution L M = = solute = material dissolved into the solvent In air , Nitrogen is the solvent and oxygen, carbon dioxide, etc. are the solutes. In sea water , Water is the solvent, and salt, magnesium chloride, etc. are the solutes. In brass , Copper is the solvent (90%), and Zinc is the solute(10%)

  21. Fig. 3.11

  22. Preparing a Solution - I • Prepare a solution of Sodium Phosphate by dissolving 3.95g of Sodium Phosphate into water and diluting it to 300.0 ml or 0.300 l ! • What is the Molarity of the salt and each of the ions? • Na3PO4 (s) + H2O(solvent) = 3 Na+(aq) + PO4-3(aq)

  23. Figure 4.22C: Titration of an unknown amount of HCl with NaOH (#3). Photo courtesy of American Color.

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