Synthesis and characterization

  The laboratory report should be in an ACS style and include a title page, an abstract, introduction, experimental, results and discussion, and references (minimum three references from the primary literature). If you are unable to access a reference, contact your instructor for assistance. Follow the guidelines given in the laboratory manual, Canvas, and consult the ACS style guide. Staple or clip the pages and turn in a printed copy with the written text at the front and the labeled and organized spectroscopic data at the end. Submit an electronic copy of the written portion of the laboratory report via Canvas upload. It is strongly recommended that you visit office hours if you have questions.  Show all calculations (this is not required to be typed) in an appendix, with each calculation clearly numbered and labeled.  Figures and Tables are to be numbered, have descriptive captions, and be cited in text.  Avoid the use of the term ‘product’, specify the correct formula.  Check spelling, verb tenses, and grammar.  Use consistent and correct reference format.  The results and discussion section is expected to be the largest section of the report. o Did your synthesis produce the desired product? Support your answer using the evidence obtained from an analysis of the experimental data (i.e. IR, UV-Vis, conductivity, magnetic susceptibility, etc.). Additional considerations are given below for the first report, which you should use as a general guide for subsequent lab reports. Compare the starting reagent and each of the synthesized compounds and determine if the syntheses were successful. Support your claims with an interpretation of the experimental data. Citations to the peer-reviewed literature or reference source are required to support claims.  Include the calculation for the product yields (using correct significant figures). Balance the following chemical reaction: _Co(NO3)2 + _NH3(aq) + _(NH4)2CO3 + _H2O2 → _[Co(NH3)4CO3]NO3 + _NH4NO3 +_H2O.  What is the limiting reagent in the reaction?  Calculate the theoretical yield and percent yield of [Co(NH3)4CO3]NO3 and [Co(NH3)5Cl]Cl2. Be sure to consider the significant figures involved in the weighing of the reactants. Comment on possible reasons as to why the percent yield is not exactly 100%.  What is the purpose of each reagent in the reactions? Why was it used in the synthesis?  Draw the most likely structures of Co(NO3)2▪6H2O, [Co(NH3)5Cl]Cl2, and [Co(NH3)4CO3]NO3. Name each of the compounds.  How can you maximize the purity of each compound?  Interpret the IR spectra and an assignment of peaks, comparing to known compounds with similar functional groups and/or the spectra obtained from the literature. o Reporting peaks to the nearest integer cm-1, not 0.01 cm-1 from peak finding. o Each IR spectrum should have your name(s) and chemical formula. o As the synthesis proceeded, compare the similarities and changes in each step of the synthesis. 82  Interpret and explain the UV-Vis spectra. Refer to section 20.7, Housecroft and Sharpe, 5e for guidance in the following interpretations and explanation. o UV-Vis spectra should list the formula, mass and volume used, concentration, w/ units. o Note colors of the various compounds and relate to the absorption maxima in the UV-visible spectra. o Explain the number of observed peaks. Compare to expected number of absorptions given geometry, dn -electron count, field strength, and Tanabe- Sugano diagram. o Explain the magnitude of the molar absorptivity in terms of the molecular structure and symmetry for each compound. (spin allowed/forbidden; Laporte allowed/forbidden, centrosymmetric vs noncentrosymmetric). See section 20.7 and Table 20.8 of Housecroft and Sharpe, Inorganic Chemistry (5e) o Explain changes in wavelength(s) of maximum absorption and the reasoning behind why it changed. o Explain changes in molar absorptivity and the reasoning behind why it changed. o Utilize the concepts of spectrochemical series and the Tanabe-Sugano diagram in the interpretations. o Explain how these observations are related to the spectrochemical series and Δoct and the factors that affect the crystal field stabilization energy.  Compare the difference in Δoct of [Co(NH3)5Cl]3+ and [Co(NH3)6]3+ (Table 20.2 textbook) o Explain the magnitude of the molar absorptivity and the relation to the type of electronic transition and corresponding molecular structures. o Include a Beer’s Law plot for starting cobalt(II) nitrate hexahydrate reagent, along with average molar absorptivity and the molar absorptivity from the one sample you measured.  Calculate, interpret, and explain the values & differences that you observed in the conductance of the solutions and molar conductivities of: o DI water vs tap water. Why differences in conductivity? o Conductance data must include mass of solute, volume of solution, measured conductivity value, and units on measured value (milli S ≠ micro S). o KCl, MgCl2, [Co(NH3)4CO3]NO3 and [Co(NH3)5Cl]Cl2.  Explain how many ions are formed in solution.  Explain the observed versus expected molar conductivity values.  Include and explain the magnetic susceptibility data [i.e. compare eff and (spin only)]. o Magnetic susceptibility data should be a separate table and for each compound include chemical formula, mass, height of sample tube, numerical value with +/- sign from the measurement, and temperature with units. o Determine and explain if the measured magnetic susceptibilities and magnetic moments 1) agree with the predicted magnetic moment considering the spin only contribution and 2) are within the typical range observed as found in Table 20.11 in Housecroft and Sharpe, Inorganic Chemistry, 5e. o Another approach would also include orbital contribution, and consideration of typical magnetic moments for specific dn complexes. See section 20.10, Housecroft and Sharpe, 5e for guidance in the above interpretations. 83 Supporting information tables. Include these completed tables as supporting information. Create your own numbered tables for calculated values in the results and discussion section. Table S1: Summary raw data, synthesis. Formula Mass of limiting reactant used in synthesis (g) Formula Mass of product obtained from synthesis (g) [Co(H2O)6](NO3)2 [Co(NH3)4CO3]NO3 [Co(NH3)4CO3]NO3 [Co(NH3)5Cl]Cl2 Table S2: Summary raw data, UV-Vis. Formula Mass used to prepare solution (g) Volume of Solution (mL) Absorbance Maximum(s) Wavelength(s) of maximum absorbance (nm) [Co(H2O)6](NO3)2 [Co(NH3)4CO3]NO3 [Co(NH3)5Cl]Cl2 Table S3: Summary raw data, magnetic susceptibility. Formula Mass (g) Length (cm) Temperature (°C) R0 R [Co(H2O)6](NO3)2 [Co(NH3)4CO3]NO3 [Co(NH3)5Cl]Cl2 Table S4: Summary raw data, conductance. Formula Mass (g) Volume of Solution (mL) Conductance (specify units) [Co(H2O)6](NO3)2 [Co(NH3)4CO3]NO3 [Co(NH3)5Cl]Cl2 KCl MgCl2