CHEM 30AL Fall 2004Iron Oxalate ComplexAscorbic Acid and Bipyridyl (or Dipyridyl or Bipyridine)Iron Oxalate ComplexCHEM 30AL Fall 2004 Experiment #11: Synthesis and Analysis of Iron oxalate (Part 3) Pre-lab Report Guidelines for the Spectrophotometric Analysis of the Iron Oxalate Complex IMPORTANT: Make sure that you always follow the proper laboratory safety protocol (refer to the course syllabus) BEFORE going to the lab. (i) Title (ii) Reference of procedures (iii) Introduction - summarize the goal(s) for this part of the experiment as well as any techniques that you will be using in achieving such goal(s). (iv) Procedures (flow chart) (see P. 101 under period 2, Colorimetric analysis of Iron) (v) MSDS information The following chemicals will require you to use the MSDS database on the Web: Ascorbic Acid and Bipyridyl (or Dipyridyl or Bipyridine) You should record the following MSDS information in your notebook for the chemicals listed above. (Printouts directly from the Web pages will NOT be accepted!!) (a) Product Name (b) Chemical Formula (c) Formula Weight (d) Melting Point; Boiling Point and Density (e) Health Hazard Data (summarize in your own words) (f) Spill and Disposal procedures (summarize in your own words) (vi) Pre-lab study questions (Must show all work for FULL credit) Complete problems 3 and 4 under period 2 on p.99. Review the concepts of equivalent weight from Chem 20L. Note: Mistake in question #3, the CORRECT balanced chemical equation should be: [Ni (NH3)m.pH2O]2+ + mHCl = mCl- + pH2O + Ni2+ + mNH4+ excess HCl + OH- = H2O (vii) Data/observations (start a NEW page for this section) Set up tables but leave blank. You MUST record all the observations into your lab notebook during your lab sessions.CHEM 30AL Fall 2004 Experiment #11: Synthesis and Analysis of the Iron oxalate Complex (Part 3) Post-lab Report Guidelines for the Spectrophotometric Analysis of the Iron Oxalate Complex This is a GROUP report (i.e. ONE post-lab report PER GROUP) (A) Abstract (refer to PART 1 post-lab guidelines for this experiment on how to write the abstract. In general, remember this format since those are the common materials that should be included in any abstract) (B) Data (see p.103 under Colorimetric Analysis) Write down the names of all the members in the group. Write out the responsibility of each member both for the experiment and for the postlab report. Data tables with all the experimental data (should have proper titles/labels) (C) Graph(s) Beer's Law calibration plot of absorbance vs. concentration for all the standard solutions Your graph must have proper title, labels. Data points must be clearly marked. Make sure you use the correct type of graph paper (i.e. mm graph paper). Note: DO NOT use your lab notebook paper to plot the graph. You can purchase the mm graph paper from the ASUCLA bookstore. If you use EXCEL to plot the graph, make sure that the gridlines are set properly. (D) Data Analysis (MUST SHOW ALL WORK FOR FULL CREDIT) Refer to Week 1 Lecture guide and concepts from 20L for this part of the report. (1) Calculate the concentrations for all the standard solutions (2) From the Beer’s law calibration graph, calculate the slope of the calibration line (with proper unit) (indicate which two points on the line you use for calculating the slope or use EXCEL to find the slope of the best fit line.) (3) from the calculated slope of the line and the absorbance of “solution B”, determine the concentration of iron in the “solution B” (with proper unit) (4) Use the result from (3) to calculate the moles of iron/gram of product (5) Use the result from (4) to calculate the experimental molecular weight of your product (6) Calculate the ratio of moles of oxalate/grams of sample (from PART 2) and the moles of iron/grams of sample (your result from (4)). This gives you the number of oxalate in the complex. (7) Determine the number of potassium ions required to neutralize the charge in the complex base on your result from (6). Explain your reasonings. (8) Propose a molecular formula for the complex neutral salt that you prepared. Report guidelines continue on NEXT pageCHEM 30L Fall 2004 Experiment #11: Synthesis and Analysis of the Iron Oxalate Complex (Part 3) Post-lab Report Guidelines (Continued) (E) Error Analysis (Refer to week 1 lecture guide as well as lecture guides FROM 20L for details on error analysis) Absolute uncertainties for various laboratory equipment are listed on page 31 of your lab manual (i) error in concentration for ONE of your standard solution (all terms identified and error bar placed on graph) (ii) error in absorbance for ONE of your standard solution (all terms identified and error bar placed on graph) (iii) calculate the range of slopes of standard line. You MUST show either mathematically how you obtain those slopes (i.e. max. slope and min. slope must be labeled clearly on your graph) (iv) error in absorbance of your “solution B” unknown (v) error in concentration of your “solution B” unknown (vi) Calculate the % inherent error for unknown solution B Note: If no error was given on the reagent bottle, you may assume the % relative error in the stock iron(II) sulfate solution is ± 1% If you use 1-ml plastic disposable syringe when preparing the standards, assume the absolute error in the syringe to be +/- 0.1mL. Use this syringe absolute error instead of the one listed on page 31 of the lab manual. (F) Conclusions (i) Calculate the % difference in your experimental molecular weight (the one for the compound you are proposing) with the theoretical molecular weight of the complex (i.e. the “expected” molecular weight) (ii) Discuss reasons for the differences in the two
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