1. Welcome (Sept 25) Sit in lab #3 groups and LAPTOPS OUT!
Compare your final answers – did you all get the same concentration of the unknown solution?
Write your group’s answer for unknown Kool Aid concentration here (in mg/mL):

2. Lab 3 Debrief How good was your calibration curve? How do you know?
Main errors to be improved next time?
ANSWER: mg/mL was right answer!

3. Light and Waves and Color!
Look at your AP Equations sheet, top box.
These equations are easy to use but we’ll practice today!
Q: What do you notice about wavelength SIZE and energy? (INVERSE)

4. DEMO: Slinky Waves Investigate these questions:
a-string
Use the all buttons and options – explore!
Investigate these questions:
What is the relationship between wavelength and energy?
What is the relationship between wavelength and frequency?

5. All energy is just waves (of different size)!
Q: Which has the higher frequency? (TOP)

6. Absorbance How did we know to use 430 or 470 nm for the Kool Aid?
Where something absorbs is the opposite (on the wheel) of what it reflects (to OUR eyeballs).
Great lab from BCC (my hometown Bellevue!)

7. Absorbance Spectrum!
What wavelength would you monitor in lab with this sample using a colorimeter?
What color is this to the eyeball?
670nm would be best.
GREEN (Chlorophyll)

8. Emission or Transmittance

9. What is this related to from Gen Chem?
Electronic transitions within different orbitals and energy levels in an atom!

10. The equations on the AP Sheet
Nm? Do you remember?

11. Practice Problem 1
In the hydrogen atom, there are four-five visible transitions: two/three purple, one teal, and one red. The red transition is a wavelength of 665 nm. What are the frequency and the energy of that transition?
Frequency = 4.51 x /sec
Energy = 2.99 x J

12. Practice Problem 2
What is the wavelength (in nm) of an electronic transition in Neon with an energy of 3.45 x J?
About 576 nm

13. Homework Day 8
Fix Lab 3 if needed (graph, conclusion, calculations, etc) and make sure it is in by W class
BIG LAB Wednesday! Wear grubby clothes and good lab shoes!
It’s NMSI Packet HW tonight!
Exercises 1-2
Beer’s Law Problem at end
Read and try exercises 3-5 (photoelectric effect)