Part 1 Lab 4 lecture Lab report writing

Part 1 (Lab 4 lecture)

Lab report writing • Scientists read for content, not for pleasure – Content should be accessible, not obscured • People estimate quality of science from quality of writing – If you want your work to be read, make sure you are writing well • No work achieves its full potential without major revising – Generally needs external input

Academic integrity • Copying of work is not permitted – Material cannot be copy verbatim from any source – No class materials may be shared electronically – You cannot share or use photocopies of the work of others • Violations will result in all parties involved being disciplined

Why keep a laboratory notebook? • In scientific research (industry) The lab notebook is like a notarized document. If your work is not recorded in a signed lab notebook, it DID NOT HAPPEN, from a legal point of view. This has important legal ramifications when patents are issued, especially when priority is at stake and billions of dollars are on the line. Since many synthetic procedures are not out of a book, it will also provide a record of the steps necessary to make a product and to verify its nature, both for yourself and for your colleagues (should your actions ever be questioned).

Why keep a laboratory notebook? • In this lab Useful data is kept handy (MWs, mp’s/bp’s, hazards, etc. ) Chance to envision the experiment in advance – Should have a schematic flow chart, not a 50 -step procedure – Chance to consider what variables are crucial to success Record of work actually performed – Value of your observations may only be obvious in hindsight – This way we know that you are not changing results to fit model

Laboratory notebook • Should be clear on tense – Flow chart: Add 350 mg of Co complex and 140 m. L of en to Me. OH soln. – Record: 352 mg of Co. Cl 3. 6 H 2 O (green powder, Aldrich, 98% purity) were added… • Should include variables crucial to success/failure – 352 mg of Co. Cl 3. 6 H 2 O (green powder, Aldrich, 98% purity) were added en masse to 5. 0 ml of Me. OH in a 25 ml RB flask. 140. m. L of en (Sigma, 99. 5%) were added dropwise over ~ 2 minutes, causing a little bubbling, and turning the solution from dark green to a medium purple. 4 chunks of a dull gray mossy zinc (TW: 117 mg, Alfa, 98%) were cleaned by swirling in 6 N HCl for ~1 min, followed by three water rinses, one Me. OH rinse, and air jet drying. No change in the color of the Zn was observed during the cleaning process. The Zn and a stirbar were added to the reaction mixture. The solution was refluxed over a sand bath (setting: 40) with the RB flask in contact with the sand with slow stirring (unable to create stable vortex at higher spin settings). A yellow solid began to appear at the top of the RB flask (outside of the liquid) after 40 min. After a total of 65 minutes of heating, the solution was directly quenched into an ice bath, allowed to cool for 7 min, and filtered through a 12 mm piece of filter paper (Fisher brand, pore size 6). A fine purple powder was obtained – no yellow solid was found in the filtrate, even after washing with cold 100% Et. OH. The Zn chunks had a pitted look and a duller luster after the reaction.

Title / Abstract / Introduction • Used to judge if full article will be read or not • Title: – Specifies system and what is interesting – Should make people want to read your article / report • Introduction: – Should answer question of why work was done – Should discuss the question being posed, and value of answer – May need to provide background information • Abstract: – Needs to be comprehensive in scope – Should only include the most essential results and conclusions – You have been asked to write an Introduction, not an Abstract

Title: Specifies system and what is interesting • Homochiral Coordination Polymer with Infinite Double-Stranded Helices • Photochemical Production of a Highly Reactive Porphyrin-Iron-Oxo Species • An Unusual 1 D Manganese Azido Complex with Novel EO/EO/EO/EE Coordination Mode: Synthesis, Structure, and Magnetic Properties • Low-Temperature Spectral Observation of the First Six-Coordinate Nitrosyl Complexes of Cobalt(II) meso-Tetratolylporphyrin with Trans Nitrogen Base Ligands • Cyanide-Bridged WV-Co. II Double-Zigzag Chain Based on an Octacoordinated W Precursor: Metamagnetism and Spin Canting • Deliberate Design of a 3 D Homochiral Cu. II/L-met/Ag. I Coordination Network Based on the Distinct Soft-Hard Recognition Principle

Spring 2007 Vanadium titles A. Separation and Spectroscopic Characterization of the Four Common Oxidation States of Vanadium B. Contributions to the visible spectrum as a result vanadiums various oxidation states C. Reduction of Vanadium and the separation of its oxidation states through ion exchange chromatography D. Using Column Chromatography and UV-vis to separate and analyze oxidation states of Vanadium E. Separation of the multicolored oxidation states of Vanadium using a resin packed chromatographic column F. separation of vandium’s oxidation states through ion exchange chromatography G. Generation and separation of four oxidation states of Vanadium via ion exchange chromatography

Part 2 (prior to lab 9)

Academic integrity • Copying of work is not permitted – Material cannot be copy verbatim from any source – No class materials may be shared electronically – You cannot share or use photocopies of the work of others • Violations will result in ALL parties involved being disciplined

Data analysis • Convert primary (raw) data to a more useful form – – – – Product mass (g) → Percent yield (%) UV-vis lmax (nm) → crystal field gap (e. V, k. J/mol, cm-1) Absorbance (dimensionless) → concentration (M) or e (L mol-1 cm-1) Diffraction peak position (°) → cubic lattice parameter (Å) Chemical formula → inner sphere coordination environment E° (V) → equilibrium constant (dimensionless) Mass change (g) → effective magnetic moment (m. B) • Answer question: How far can my results be trusted? – – What is the error for weighing samples? What is the error in an IR measurement? What is the error in a uv-vis measurement? What is the error in an x-ray diffraction experiment?

Discussion • Answer: What scientific insights were gained from work? – Must be general science, not “I learned to take uv-vis spectra” – Be sure to cover broad trends • • • Ability of ions to stabilize Cu oxidation states (lab 1) Properties that are similar / different for geometric isomers (lab 2) Ability of ion exchange chromatography to separate V complexes (lab 3) Influence of ligands on # of unpaired electrons (lab 4) Arrangement of ligands into spectrochemical series (lab 5) Favored coordination geometry (lab 6) – Can discuss difficult concepts in more detail • Spectrochemical series position of Co(NH 3)5 Cl – Generally should discuss results of the formal questions – Don’t forget to include answer to questions in the text

Group exercise #1 • As a group, identify the topics which should be discussed in each of the three sections of your write-up of the Cu 2 Hg. I 4 lab. – Introduction – Data analysis – Conclusions

Revision exercise #2 • Goal: submit an improved version of your lab 6 (MIMT) report – Take your report to the University Writing Center for feedback in paper and electronic form [computers available there] – Can skip the “Questions” section in your re-write – focus on text – Turn in your original and revised lab reports to me, with UWC comments if they are available – Due date: Class period on April 30 th (two weeks from today) Note: no other lab report is due that week • Hours for University Writing Center: – Mon-Wed: 10 AM – 10 PM – Thur: 10 AM – 7 PM – Sun: 2 PM – 7 PM • Web site: http: //writingprogram. hfa. umass. edu/writingcenter. asp • Located in the Learning Commons of the WE Du. Bois Library

Group exercise #2 • In your assigned group, please complete the NA handout • Make sure you follow the proper sig. fig. rules for: – Multiplication/division (keep minimum # of SF’s) – Addition/subtraction (keep only decimals used for all #’s) • Completed work due at beginning of class, Mon. 4/23 • Work of the group as a whole will be evaluated