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site map read first about course lab manual appendix

Lab I

Lab II

Lab III

Lab IV

Lab V

Lab VI

Lab VII

Lab VIII

Lab IX

Lab X

Lab XI

Lab XII

Lab III: Part 1 of the 2-Part Dual Unknown Lab

Pre-lab Work

Reading Assignment:

  1. Introduction to Functional Groups:
    Hornback; pp. 50-53
  2. Melting Point Determination:
    Appendix & Mohrig
    --2nd edition Technique 10.1-10.3, & 10.6, pp. 116-123, 125, or 3rd edition Techniques 14.1-14.4, pp. 175-180.
  3. Boiling Point Determination:
    Appendix & Mohrig
    --2nd edition Technique 11.1-11.3, pp. 128-137, or 3rd edition Techniques 13.1-13.3 pp. 142-157.

Pre-lab Questions:
(Please turn in the answers to these questions when you arrive to lab.)

1. Describe what you would see in a MelTemp apparatus as a compound with a melting point of
160-163 deg. C slowly went from 150 deg. C to 170 deg. C.
2. How will you know when you've obtained the boiling point of your unknown liquid using a simple distillation apparatus?
3. Why should you never completely boil all the liquid out of your distillation flask when running a distillation?
4. What are the seven possible major functional groups that could be in your unknown compounds?
5. Using ChemDraw, create a single compound using all seven major functional groups listed in question #4.  Note: you can use more than 7 functional groups, such as alkanes, to help you create your MONSTER structure. :)


Introduction

This lab is a 2 part experiment that uses wet chemical techniques and spectroscopic data to collect physical and chemical property information about two unknowns, a solid and a liquid at room temperature.

Each unknown will contain one or more of the following major functional groups:

ALCOHOL, ALDEHYDE, AMINE, CARBOXYLIC ACID, KETONE, NITRILE, PHENOL.

The unknown might also contain one of these other functional groups: alkene, alkyne, amide, aromatic, ester, ether, halide, and nitro.

Throughout the next two labs and during some portions of our lecture, you will work with your partner to discover the physical properties and possible functional groups that make each unknown unique. From this information, you should be able to identify your unknowns from a list of possible compounds that will be given to you around the end of Part 2.

Safety Notes

Wear gloves and goggles when handling your unknown compounds. Simple distillation should be carried out in the hood.

Experimental Work

Objective:

  • To collect preliminary classification and physical property information for
    each unknown compound using the following techniques:

Experimental Procedure

Melting Point/Boiling Point
Obtain the boiling point of the liquid unknown using simple distillation and the melting point of the solid unknown using a Mel-Temp. Both of these procedures can be found in the Appendix. It is important to record the voltage or power level used when obtaining your melting point. If the wrong voltage or power level is used, the recorded melting point will be incorrect. (Mohrig, Figure 10.5, page 120)

Waste Disposal and Clean-up

  1. Dispose of used melting point capillaries in the glass disposal box.
  2. Transfer your distilled liquid to a labelled glass vial and store in your personal tote.
  3. Rinse your glassware with acetone and dispose of the acetone rinse in the flammables waste bottle.


Post-Lab Question:
(Please turn in the answers to these questions when you arrive at your NEXT lab.)

1. In an Excel data table, list your unknown number, your partner's unknown number(s), your partner's name(s), and the respective boiling and melting points.  (Please include the setting on the Variac for the boiling point AND the setting on the MelTemp for each melting point.)