2.1: Pre-lab assignment
- Page ID
- 401633
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A critical skill you will gain in this module is to be able to correctly use volumetric pipettes and volumetric flasks to create solutions. Please prepare by reading all of the contents of Module 2 and watch the videos below to learn how to use the volumetric glassware correctly.
Pre-Lab Assignment
- Read the contents of this module
- Download the example calibration template (Excel document), open it, and examine its contents (it is linked within the reading assignment in this module and copied here for convenience: Link for Duke Students).
- Write the following in your notebook before the start of lab. Your instructors will check your notebook at the start of the lab period.
- Draw the structure of bromocresol green in its basic and acidic forms. Which is the form you will measure, and what is the wavelength used to monitor its concentration?
- Transcribe a table into your notebook so that you have an organized place to record absorbance readings. Leave room to record three absorbance readings for each solution F through B (you will read them backward, in the order F, E, D, C, B) and to record the average and standard deviation of those readings. You will also need a place to record readings for the "control" solution and the "unknown solution".
- Calculate the molarity of bromocresol green in each solution. (Remember: \(M_1V_1=M_2V_2\).) Also calculate the error associated with each solution's concentration.
You should complete the above tasks prior to the start of your laboratory period.
Instructions
Watch the following videos. The first two videos explain the correct use of volumetric pipettes and bulbs. The third video explains the correct use of volumetric flasks. And the fourth explains how to use automatic pipettes.
| How to use Volumetric Pipettes and pipette bulbs | |
| How to use volumetric flasks | |
| How to use an automatic pipette (aka "pipetter" or "pipetteman" | |
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