Last year science was Physics. For this year science is Physics. We study over the fundamental concept in chemistry from atom to the periodic table. Besides learning from the slide and practices solving problems, we were doing a chemistry lab about Quantized Energy Levels in different compounds.
Here is my lab report:
- Why do we see colors in the flame tests?
We see colors in the flame test because the electrons were getting excited when exposed to energy and jump to a higher level shell, then release a specific frequency proton while falling back to the original shell.
- How will we be testing the substances qualitatively?
We will be testing the substances qualitatively by observing the color of the flame which the atom emitted.
Procedure:
- Light the Bunsen burner (turn the gas on so you can just hear it, then use the striker)
- Place the wood splint for each compound into the flame using tongs or tweezers- ONE AT A TIME!
- Take note of the color of the flame and return the wood splint to the solution.
- Carefully put the stoppers back on the solutions! Make sure the station looks like it did when you started! Let me know if you need new splints!
- Wash your hands thoroughly before leaving the laboratory
Data Table:
Compound
|
Color of Flame (qualitative)
|
Wavelengths of light (in Å) (quantitative)
|
| Barium Chloride |
Green |
560 – 520 nm |
| Calcium Chloride |
Orange |
635 – 590 nm |
| Copper (II) Chloride |
Cyan |
520 – 490 nm |
| Lithium Chloride |
Pink |
700 – 635 nm |
| Potassium Chloride |
Purple |
450 – 400 nm |
| Strontium Chloride |
Red |
700 – 635 nm |
| Unknown #1 |
Pink |
700 – 635 nm |
Discussion and Analysis:
- What observation did you make that allowed you to come up with the wavelengths for each chemical? What happened to the atom (and more specifically the electrons) that caused you to see that change?
A color emitted by the compound has a specific light frequency and wavelength. The difference energy in which the electron in the ground and the excited states could be explained by the light photon that electrons released. The higher the frequency of the photon, the more quantized energy level is. For example, Potassium Chloride emitted purple photons which has a higher quantized energy level compare to Strongtium Chloride which emitted red that has lower quantized energy level.
- The unknown compound is one of the other six. Identify it and explain HOW you figured it out using the results of your experiment.
When the color of the unknown compound emitted (pink) compare to the color of the known compound emitted, we see Lithium Chloride also emitted pink as well. So the unknown compound is Lithium Chloride.
Conclusion: What are two possible sources of error for this lab? How would the errors affect your lab? What would you do differently next time to counteract these errors?
Two possible sources of error for this lab are identifying the color of the flame incorrectly and using wood splint as the tool to hold the compound in the flame. The missed identify the color could result in false wavelength as well the quantized energy levels of the compound. The wood splint that held the compound in the flame, got burn and possibly emitted flame with a different color that could buffer us from identifying the color from the compound. To counteract these errors in the next time test, the procedure should include taking pictures of the flame and identifying its color by using computer software and replacing wood splint with a metal splint or a metal spoons instead.
