DRAFT: This module has unpublished changes.
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Cooling Baths

DRAFT: This module has unpublished changes.

Equipment

  

UV/visible light source

Thermostat (3)

RedTide spectrophotometer

Interface (2 GLX)

Thermostated Cell Holder

Automatic pipettes

Quartz cell

Gas regulator

Nitrogen

 

Solutions to prepare or obtain:

1 M Sulfuric Acid

Acetone

Deionized Water

Saturated Iodine solution

 

Method

  

Set up:

                The light source is connected to the cell holder attached to the red-tide spectrophotometer that is connected to a GLX. The cell holder is set to the same temperature as the solutions (3 temperatures observed). The light source creates a beam of light through the cell holder. The light passes through the cell to the fiber optics detected by the spectrophotometer. At low temperatures the cell holder is flushed with Argon or Nitrogen to prevent condensation in the cell holder and on the cell. If condensation occurred the absorption of the species would be negatively affected.

 

Configuring the spectrophotometer and GLX:

 

               The spectrophotometer and GLX must be configured with a dark and reference point. First save the dark. In the cell holder, block the path of the light with an object. Then press F1 to save the dark. For the reference point, fill the cell with deionized water, wipe the cell clean, ensure no bubbles are in the cell and place the cell into the cell holder. Next hit F2 on the GLX to save the reference. Go to time acquisition on the GLX and set the scan mode to time acquisition and the wavelength to 270nm. Hit F4 to close. Change the vertical axis to absorbance (hit the check mark twice to change y-axis). Collect a blank run to ensure that there is no absorbance.

 

Performing the experiment:


                This experiment was performed at three temperatures 35, 15 and 1°C. At each temperature four runs were performed. Each run had a different concentration of reactant. The table below provides the specific concentrations of reactant for each run.

To begin the experiment combine the correct amount of acid, water and Iodine solution for that run into the cell. Next add the required amount of Acetone. Once the acetone is added the reaction begins, so the cell is quickly mixed and placed into the cell holder. The cell must be clean and without bubbles. Immediately begin recording data. Stop the collection of data once the absorbance is zero.

DRAFT: This module has unpublished changes.