1. Investigating the relationship between Molar Concentration and Absorbance of Light Beer’s Law Link to spec 20 video

2. Relationship between absorbance of light, emission of light and electron quantum leaps Absorb E = e- ground → excited Emit Light = e- excited → ground Link to Laser Phet

3. Prelab Questions 1) What color(s) light is reflected by a red T- shirt and what color(s) is/are absorbed? Ans: Reflects red; absorbs other colors

4. 2)If a compound has the spectrum below what color is it?

5. % Transmittance Measure of % of light photons that pass through a sample: Light source Sample Link to Beer’s Law Phet %T = I/I o x 100 A = - log T= - log.60 = 0.22

6. Beer’s Law Number of photons absorbed is directly proportional to concentration in moles/Liter A = ε c l Where A = absorbanc e ε = extinction coefficient (how strongly chemical absorbs light at a particular wavelength) l = pathlength (usually 1 cm) C = concentration

7. Determining Unknown Concentration from a Standard Curve

8. Measuring Light Absorbance or Transmittance Using a Spec 20 Link to spec 20 video Sample holder Adjust wavelength Set Blank at 100.0% T, 0.00 A Flinn video