How is the Spectronic 20 used for qualitative analysis of colored solutions?
Equipment and material: Spectronic 20, cuvettes, a stick of white chalk, distilled water, cobalt chloride solution. [Teaching Standard D- Make accessible science tools] Before you begin the experiment, your teacher will review with you the proper techniques in handling the Spec. 20. General Operating Procedure: 1. Turn on the machine; pilot lamp will light. Allow 5 minutes for warm up. 2. Select the desired wavelength. 3. With the sample chamber empty, set the meter to zero T. (The power switch is also the zero control knob.) 4. Insert a cuvette containing the reference solvent (distilled water) and set the meter to 100% T. 5. Insert the sample; record % T or Abs. 6. Repeat steps 2 through 5. To ensure good readings 1. All solutions must be free of bubbles. (We are not analyzing air!) 2. Cuvette should be 1/2 to 3/4 filled. 3. Cuvette should be clean, and dry on the outside. 4. Index mark on the cuvette should be aligned with the mark on the instrument.
