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misterrvincen misterrvincen
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Posts: 5
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10 years ago
Can anyone help me with this lab? Or have it completed? Please and thank you.

PART 1

Begin by viewing the following Thinkwell video

13.3.2    CIA Demonstration: The Synthesis of Nylon

After you watch the above video, answer the questions below in sufficient detail:

(a) (2 pts.) What is the name of the type of reaction that you see in this demonstration? Describe IN YOUR OWN WORDS what happens, generally speaking, in this type of reaction. Be detailed in your discussion.

Answer:

(b) (2 pts.) There are two chemicals used in this reaction, 1,6-hexadiamine (which is in a water solution) and adipoyl chloride (which is in a hexane solution). Think back to what you learned in this course about solutions and intermolecular forces. Why don’t these to “mix” together (in other words, make a homogenous solution) when combined? Why do they separate into layers? Be clear and detailed in your response.

Answer:

(c) (2 pts.) What functional groups are the key players in this reaction? How so? Explain clearly and in detail.

Answer:

(d) (2 pts.) Explain, in as much detail as possible, why the nylon is only created at the INTERFACE between these two solutions.

Answer:




PART 2

Please watch the following Thinkwell video:

15.1.2  CIA Demonstration: Recrystallization

After you watch the above video, answer the questions below in sufficient detail:

(a) (3 pts.) Describe, in as much detail as possible, the process of recrystallization as a method for purification of a solid. How does it work? What do you do?

Answer:

(b) (2 pts.) How do you make a “supersaturated” solution—what are the specific steps? How is this different than a “saturated” solution?

Answer:

(c) Describe SPECIFICALLY what happens when solute is added to:
    (1 pts.) a saturated solution

   Answer:

   [ii] (1 pts.) an unsaturated solution

   Answer:

   [iii] (1 pts.) a supersaturated solution

   Answer:

(d) (2 pts.) What is the role of vacuum filtration in this process of Recrystallization? How do you do it? Be detailed and specific, and include all steps.

Answer:

(e) (2 pts.) Suppose we are dealing with calcium chloride as opposed to the chemical in the video. If a solution contains 70 g of calcium chloride per 100 g of water at 25 degrees Celsius, is the solution unsaturated, saturated, or supersaturated? Explain your answer. You may want to refer to Figure 13.4 in your text for help, or perhaps refer to the image at http://chemistrysolutions.files.wordpress.com/2011/03/capturada16.jpg..

Answer:





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Staff Member
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10 years ago
Follow forum rules, two questions per topic!

(b) (2 pts.) There are two chemicals used in this reaction, 1,6-hexadiamine (which is in a water solution) and adipoyl chloride (which is in a hexane solution). Think back to what you learned in this course about solutions and intermolecular forces. Why don’t these to “mix” together (in other words, make a homogenous solution) when combined? Why do they separate into layers? Be clear and detailed in your response.

Answer:

Water is a polar solvent, hexane non polar, so they are immiscible (won't mix). As there is a density difference as well, they will separate into two layers.

(e) (2 pts.) Suppose we are dealing with calcium chloride as opposed to the chemical in the video. If a solution contains 70 g of calcium chloride per 100 g of water at 25 degrees Celsius, is the solution unsaturated, saturated, or supersaturated? Explain your answer. You may want to refer to Figure 13.4 in your text for help, or perhaps refer to the image at http://chemistrysolutions.files.wordpress.com/2011/03/capturada16.jpg..

Looking up the literature for CaCl2, it is saturated at 74.5 g/100mL (20 °C). In the problem, the temperature is increased, and in general, as temperature increases, so does the solubility curve. Since in the problem 25 C is the temperature, the saturation point of 74.5 is going to be passed, thus the solution is supersaturated at 25 degrees C at the 70/100 g concentration. Even easier, looking at a solubility curve, you can easily see that the curve for CaCl2 is above that of NaCl (which is the reference solute dissolved in 100 mg of H20). Anything above this line is supersaturated..and below unsaturated:

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