Lesson 4 Lab: Chromatography and Ionic versus Covalent Bonds
PART 1
Begin by viewing the following Thinkwell video
27.1.2 CIA Demonstration: Chromatography
After you watch the above video, answer the questions below in sufficient detail:
(a) (3 pts.) This video discusses 3 different types of chromatography. List each one mentioned, and describe their differences in as much detail as possible. Which one was used in this lab demonstration?
Answer: Gas – to separate mixes of gasses
High performance liquid – separate liquids
Thin layer – separate organic compounds
TLC was used in the demonstration.
(b) (2 pts.) How did chromatography get its name, and how is it used differently now compared to in the past (according to the video)? What is it and how does it work?
Answer: Originally everything was separated because they looked different. Now, we find methods to separate things into their basic forms, such as the color purple, breaking it apart so that it shows that it is just a mix of yellow and blue.
(c) Suppose I melted a green popsicle and ran a chromatogram of the resulting substrate.
(1 pts.) In the simplist case, what would I expect to see? Include as much
detail as possible.
Answer:
[ii] (4 pts.) Suppose that the dot/area representing the longest wavelength of
color in this situation was located 29 mm from the baseline, and the dot/area
representing the shortest wavelength of color was located 44 mm from the
baseline (see Figure 9.4 on page 288 for help). If the solvent traveled 65 mm
from the baseline, what was the Rf for each of these two components of the
sample?
[SHOW ALL WORK]
Answer:
[iii] (2 pts.) What does this mean? Why, in this case, would one component of the sample travel farther than the other? What’s going on here—what causes this to happen?
Answer:
(d) (2 pts) What is the difference between the stationary phase and the mobile phase as it relates to this lab? What was the stationary phase in this demonstration? What was the mobile phase in this demonstration?
Answer:
PART 2
Please watch the following Thinkwell video:
9.1.3 CIA Demonstration: Conductivity Apparatus-Ionic versus Covalent Bonds
After you watch the above video, answer the questions below in sufficient detail:
(a) (1 pts.) Please state in the blanks provided whether the following samples from the lab were an electrolyte or a nonelectrolyte:
Pure water: ________________ Drain cleaner: _______________
Ethanol: ________________ Sucrose: _______________
Sodium chloride: ________________
(b) (2 pts.) Explain your answers to (a) above detail according to what you witnessed in this lab demonstration. What is the evidence for each? How did you arrive at your answers? What does the type of chemical bond have to do with this? Be specific.
Answer:
(c) (3 pts.) If you have ever been to a public pool, you know that you are required to exit the pool when there is lightning in the sky. But consider your results from part (a) above and what you learned in this lab, paying particular attention to the very first demonstration that the instructor shows you regarding the light bulb. Does this protocol make sense in light of the data from this demonstration, or is it contradictory? Why or why not? We are talking about water, here, right? Is there anything else going on in this case, chemically speaking, that would change the way we look at this situation?
Answer:
DON'T FORGET TO INCLUDE REFERENCES IN ORDER TO FULLY DEVELOP YOUR ANSWERS AND GO BEYOND THE BASICS OF THE QUESTION!!!
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