LabNotesvp

advertisement

ORGANIC CHEMISTRY LAB NOTES

Revised 01.08.2010

INTRODUCTION

This is a laboratory course designed to develop your skills in dealing with experimental problems. A good experimentalist must have several important qualifications: the ability to pay strict attention to detail, to reason scientifically, and to master new techniques and manipulate equipment.

Laboratory work is not a jumble of unrelated operations; there must be a good reason for everything that you do. IF YOU DO NOT KNOW WHAT YOU ARE DOING AND WHY YOU ARE

DOING IT, YOU DO NOT BELONG IN A LABORATORY!

I. LAB NOTEBOOKS

An accurate record of your experimental procedure, results, observations, and conclusions is an indispensable part of scientific work. Human memory is faulty and unreliable enough that a written record of results is necessary for future reference. Your notebook should be written so that it is intelligible to anyone conversant with the subject. See your instructor if you have any questions about the desired notebook format.

Notebooks must be hardbound and written in permanent ink. We require a bound lab notebook by

Hayden-McNeill, Inc. (ISBN #1-930882-74-2, available at the MTU bookstore) with duplicate pages.

This notebook should have sufficient pages to last through both organic lab courses (2411 and

2421). NOTE: You must use a ball point or other hard-tip pen and write firmly for legible duplicate

pages. The duplicate, carbon copy pages are to be turned in to your instructor each week for grading.

A. Preliminary Notebook Entries (10pts)

Preparation is required before coming into the laboratory. This will include reading the experiment and techniques involved, and making some preliminary entries into your notebook. Be sure to read both Dr. Logue’s lab notes for the experiment as well as the readings assigned from Zubrick before beginning your preliminary notebook. Preparation for a lab, which includes reading and writing the preliminary notebook, should take two hours or more. You will find the experiments much easier and capable of being completed much faster if you are thoroughly acquainted with the experiments beforehand.

Preliminary notebooks are due before the experiment begins! If your preliminary notebook is not complete, then you will be asked to leave and finish it before beginning the experiment. An unprepared student is a safety hazard to other students. Moreover, the unprepared student will have no chance of finishing the experiment in the time we allow.

The preliminary notebook entries will vary with the type of experiment, but will generally include:

1.

A Title

Every experiment must have a title. The title should provide enough of an explanation as to what was done in the experiment while remaining concise. A title which is over simplified can be misleading. i.e. “Making Trimyristin” Did you synthesize it from scratch, isolate it from something, or simply draw a picture of it? A more complete, yet concise title would be, “Isolation of Trimyristin from Nutmeg”

2.

A Reference

Reference the experiment, the techniques, and any handbooks (or web sites) used in the preparation for the experiment. Please note that page numbers must be included.

If one is referencing a website, then be sure to include title of the webpage and the date the page was accessed. In general, the ACS format for citations should be used.

3.

An Introduction

Keep the introduction brief. Introduce the experiment using only a sentence or two in your

own words. A good introduction should state what you are going to do and how you will verify that you have done it. Theory and procedure belong somewhere else!

4.

The Main Reaction

Include a balanced equation for the main chemical reaction involved in the experiment. When applicable, it is also helpful to list any potential side reactions that may occur. The main reaction should not contain any mechanisms.

Note that this entry is appropriate only when the experiment involves a chemical reaction

(i.e., a synthesis). Most of the early CH2411 experiments involve techniques rather than syntheses.

5.

Table of Reagents And Products

Include the following information for all chemicals (every chemical used or synthesized in the experiment): a) chemical formula and/or structure b) amounts to be used in the experiment (weight in grams, volume in milliliters, etc.)

.

Moles used should be entered as a separate column. c) important physical constants

i) Include molecular weight and moles for the reactants and products of the main chemical reaction when applicable.

ii) Include only physical constants which are pertinent to the experiment (i.e. melting point, boiling point, density, etc.).

d) waste disposal

See solvent table for a good example of this portion of the preliminary notebook as well as a valuable resource of important physical constants of some common organic solvents.

Be Careful: By all reagents, we mean all. This includes solvents, acid, bases, etc. Too many times students are found trying to evaporate a solvent from their flask and they have no idea what temperature to set the hot water bath. Had they been aptly prepared and known the boiling point for the solvent, they would be spending their time more wisely than being perplexed.

Physical constants may also be found in handbooks such as: a) CRC Handbook of Chemistry and Physics, CRC Press, Inc. Boca Raton, Florida.

[Call #QD65.C5, Location: Reference stacks on main floor or Circulating collection on

2nd floor of campus library] b) Lange’s Handbook of Chemistry, McGraw-Hill Book Company, New York, New York.

[Call #QD65.Lzh, Location: Circulating Collection, 2nd floor of campus library] c) The Merck Index, Merck & Co., Inc., Rahway, New Jersey.

[Call #RS51.M4..., Reference stacks of main floor or Circulating collection on 2nd floor of campus library] d) Aldrich Catalog Handbook of Fine Chemicals, Aldrich Chemical Co., Inc., Milwaukee,

Wisconsin.

Or web sites such as: a) http://www.emolecules.com/ b) http://www.jtbaker.com/asp/Catalog.asp

c) http://www.chemexper.com/

6.

Theoretical Calculation

Any good calculation in a notebook will begin with a good sample calculation. This means writing out your calculation as an equation of just variables. Then write a second equation in which the variables have been replaced with the values you will use. Be sure to include the units in the equation and in the final answer. Once you arrive at the final answer, put a box around it so that it is easy for a reader to find. Ask your instructor for more information.

A good calculation for yield will save you time later in the experiment.

7.

An Outline of Procedure

Think about the most important steps of the experiment and then condense the procedure.

Put these few steps in some type of outline form or flow chart. Do not include details in the outline and remember that reagent amounts belong in the reagent table. If you find it helpful to outline the experiment in more detail, do so outside of your notebook! Please note that you are not allowed to bring the online notes for an experiment to the lab. There is a point deduction associated with bringing the notes to lab.

B. Experimental Section (40PTS)

The experimental section of the notebook is due in lab on completion of the experiment. During the course of the experiment, record all data, observations (and possible interpretations if necessary), problems encountered and how you solved them, as well as any chromatograms, spectra, etc. If a portion of the lab has to be repeated due to experimenter error, then document everything. i.e. what was the source of the error and everything you did the second time. A good experimental section should be detailed enough that anyone can look at your work and tell exactly what you have or have not done correctly. Think of it as a record not only for others but for yourself as well.

Take pride in your ability to be observant and documenting your labor!

Do not copy the procedure from the lab notes or other literature source into your note book beforehand, but write everything you do or observe as it occurs.

Use a passive third person past tense for writing.

Experimental sections can either be delivered in a prose, paragraph form.

Otherwise, a bulleted outline format of what you have done and observed is also viable.

Ask your instructor ahead of time what format they prefer to see from you.

This section should include:

1.

the procedure as performed

2.

all pertinent data (weights, volumes, mp, bp, etc.)

3.

all observations (changes in appearance, temp, etc.)

An Acid Test for a Good Notebook 1

If this were someone else’s notebook, could you duplicate the results exactly?

C. Postlab Exercise (35pts)

After completion of the experiment, you should complete the postlab exercise found at the end of each experiment. Postlab exercises should be turned-in in the lab. Name and section number are

required on the postlabs. Postlabs without name and/or section number will be penalized with a loss of 2 points each for name and section number. The format of the postlab exercises may vary somewhat depending upon the nature of the experiment, but will generally require:

1.

results (% yield, % composition, etc.)

2.

product purity (melting point, boiling point, or some other indication)

3.

postlab questions and/or interpretation of spectra

There will also be a few thought-provoking questions in the postlab exercise for you to answer. The answers to the questions are not necessarily in the experiment or your text and may require you to use your "chemical intuition".

II. GRADING

Each typical experiment will be worth 95 points, with the following distribution:

1.

Preparation (20 points)

 10pts - Preliminary Notebook

 10pts - In-lab Quiz (multiple choice or fill-in the blank, based on theory, procedure, techniques, etc.)

2.

Experimental Section (40 points)

3.

Postlab Exercise (35 points)

1.

~15pts - Product*

2.

~15pts - Questions

* Product

points will be based on the product having the proper appearance, purity as indicated by M.P. or B.P. and/or TLC analysis, as well as completeness and neatness of the label. When appropriate, you will be graded on the % yield. When turning in your product for grading, follow the label format.

Preparation and attitude will be taken into consideration by the instructor in the assignment of the instructor evaluation points. Five of the fifteen points will be based on the instructor’s evaluation of your ability to manage time in the laboratory. To obtain all five of these points, plan to: 1) arrive at lab on time; 2) use lab time efficiently; 3) finish experiment and clean-up within the time allotted for the experiment.

In addition, deductions from the instructor evaluation points will be made for safety infractions.

Typical infractions include:

1.

tardiness

2.

conducting unsafe procedures

3.

failure to clean up spills

4.

improper disposal of waste

5.

failure to return common equipment

6.

failure to keep your work area orderly and clean

III. LATE PAPER POLICY

A. Preliminary notebook entries are due at the beginning of the lab on the day you start the

experiment. If not completed in time, you will not be allowed to work in lab. You will have to complete the prelab and make up lab with some other section in the same week.

B. Experimental Portions of the lab notebook are due at the end of the completed experiment unless otherwise instructed. You will receive 0 points if not turned in on time. No excuses will be accepted.

C. Postlab Exercises are due during the next lab period after the completion of the experiments.

Postlab exercises should be turned-in in the lab. Name and section number are required on the postlabs. Postlabs without name and/or section number will be penalized with a loss of 2 points each for name and section number. Postlabs turned in late will receive 0 points – this includes postlab exercises of absent / make-up students!

NO EXCUSES!

IV. ABSENCE POLICY

A responsible attitude towards attendance is critical to the efficient operation of this laboratory course. Much of the same responsibility and courtesy shown to an employer are expected from students enrolled in this course, including attendance during the weekly scheduled lab time. Please make note of the following:

1.

To make up a lab, you must complete an absence request and obtain permission from the lab supervisor or faculty advisor.

2.

Follow the instructions on the absence request carefully. Your absence request will be reviewed and, if approved, forwarded to the appropriate lab instructors.

3.

If after approval of the absence request you decide to perform the experiment in your own section, please email lab supervisor. Remember there would be other students whose request was not approved due to lack of space availability.

IMPORTANT ABSENCE POLICY NOTES

 All absences must be made up within one week of the missed lab. To facilitate this, please complete an absence request form or notify the lab supervisor as soon as you know you

will miss a laboratory!

 Postlab exercises must be handed in the lab the week they are due. Postlab turned in late

 will be assigned 0 points.

You will find the lab supervisor’s phone number, office number, and e-mail address on the

Organic Lab home page.

 Three unexcused absences will result in an F for the course. If you suspect that you will be absent more than once, it is strongly recommended that you obtain validation of your absence excuse from a physician, counselor, or clergy.

V. WASTE DISPOSAL

Wastes are divided into two basic categories:

1.

Those that can be flushed down the drain (run water while pouring these liquids in the drain; continue running water for a few minutes afterward:

 aqueous solutions of salts, acids, and bases water soluble alcohols and acetone.

2.

Those which must be collected and shipped to a disposal site. Chemicals in this category will be deposited in the special containers provided.

NOTE: There are separate containers for nonhalogenated organic waste and halogenated organic waste (organic compounds with C-Cl or C-Br bonds), which are more costly to dispose of.

VI. ACCIDENTS AND/OR INJURIES

Notify your instructor of any accident or injury at once! If medical attention is deemed necessary, you will be transported to the Portage Medical Clinic (MTU Health Center) or to the Portage View

Hospital. Do not leave the laboratory by yourself!

VII. CHECK-OUT/EARLY CHECK-OUT POLICY/PROCEDURE

You must check out of your drawer by the last scheduled lab in the term you drop the lab (usually

4:00p Thursday, week 14 during Fall and Spring Semesters; Wednesday of last week of the track during Summer). Complete an absence request . You may pick any time or day during a regularlyscheduled lab session, but do not pick a time which is during the 1st or last hour of the session

(see home page for link to lab schedule).

1.

When you arrive in lab, put on your goggles and let the instructor know that you need to check out of your drawer. Since you completed an absence request form, the instructor should be expecting you and will have the necessary paperwork ready.

2.

Remove everything from your drawer and make sure that everything is clean and present.

A list of drawer equipment and the approximate replacement cost is posted on the lab bulletin boards. Please place desk equipment on the bench in the approximate order of the list. Equipment replacements must be purchased from Chemistry Stores (B002)*

3.

Tell the instructor when you are ready to be checked out. The instructor will obtain your original check-in certificate and then check over each piece of listed glassware carefully.

You will be expected to replace any equipment found unsuitable. Make sure the instructor

signs and dates your check-out certificate before you leave. The instructor will then change the lock on the drawer.

NOTE: NEVER LEAVE YOUR EQUIPMENT UNATTENDED!

1 Zubrick, James W., The Organic Chem Lab Survival Manual: A Student's Guide to Techniques, 7th Edn.,

John Wiley & Sons, Inc., 2004, p. 21

Download