General Instructions

In this activity, you will link the types of intermolecular forces possible between atoms or molecules in condensed phases (dispersion forces, dipole-dipole attractions, and hydrogen bonding), correlate the types of intermolecular forces experienced by specific molecules with their structures, explain the relationship between the intermolecular forces present within a substance and the temperatures associated with changes in its physical state, and identify and contrast inter and intramolecular forces. To successfully achieve this, you will need to review module five's study materials (bonding and chemical interactions).

Step 1: Select and Reflect

Read the topic below and demonstrate your understanding of intermolecular forces in theoretical and practical settings.

• Intermolecular forces

Step 2: Respond

Using supporting data for your arguments, prepare a 300-350 words written piece that answers any of the following questions based on the scenario you selected. 

Case Scenario 1: 

The chemistry lab has two students tasked with understanding the different types of intermolecular forces possible between atoms and molecules in dispersed phases. The first student studies two gases, hydrogen and oxygen, and their interaction in a dispersed phase. The student observes the two gases undergoing hydrogen bonding. 

The second student studies two liquids, water and ethanol, and their interaction in a dispersed phase. The student observes the two liquids undergoing hydrophobic interactions and hydrogen bonding. 

Questions:

1. Describe the strongest type of intermolecular force that occurs between two molecules containing hydrogen atoms and other atoms, like oxygen.
2. Describe the interactions and bonding taking place as observed by the second student.

Case Scenario 2: 

You are a chemist in a laboratory tasked with determining the intermolecular forces experienced by two specific molecules: ethanol (C2H6O) and propane (C3H8). 

Questions: 

1. What type of intermolecular force is present in ethanol? 
2. What type of intermolecular force is present in propane? 
3. How does the structure of ethanol contribute to the intermolecular forces present? 
4. How does the structure of propane contribute to the intermolecular forces present? 
5. How would the intermolecular forces be affected if the temperature of the molecules was increased?

Case Scenario 3:

The intermolecular forces present in a substance can greatly influence the temperatures at which it changes its physical state. For example, when a substance with strong intermolecular forces is heated, it will require a higher temperature to transition from a solid to a liquid or from a liquid to a gas. On the other hand, a substance with weaker intermolecular forces will require less energy to transition between different physical states.

Questions:

1. What factors impact the strength of intermolecular forces in a substance?
2. How do intermolecular forces affect a substance's boiling and melting points?
3. What happens to intermolecular forces when a substance transitions from one physical state to another?
4. How does the strength of intermolecular forces influence the ease of changing a substance’s physical state?

Step 3: Share 

To share your work, click on the “Add a new discussion topic” button under this post and paste your work into the “Message” box. Make sure to reference others’ intellectual property when necessary. All references should follow 7th Edition APA formatting. For further instructions, see the resource on the Himmelfarb Health Sciences Library: APA citation resource (N.B.: references are excluded from word counts).

Step 4: Interact 

To complete the activity, evaluate and categorize the work from one of your peers based on items A - E of the rubric below. Provide a rationale for the grade you have provided and comments or suggestions for improvement. To post a reply, click “Reply” on a particular discussion, write your feedback, and click “Post to forum.” You can use the list below as an example:

 Item A is  ____________ because ____________. My suggestions for improvement are ____________.
 Item B is  ____________ because ____________. My suggestions for improvement are ____________.
Item C is ____________  because ____________. My suggestions for improvement are ____________.
Item D is ____________  because ____________. My suggestions for improvement are ____________.
Item E is ____________  because ____________. My suggestions for improvement are ____________.

OPTIONAL Step 5: Interact (10 minutes)

If you would like to, you can reply to your peers' posts in a respectful and professional manner. Ensure that your post engages your peers' ideas by including a reflection on their comments, sharing ideas of other potential difficulties and parties involved, or asking thought-provoking questions. If a peer comments on your posting, please reply. To post a reply, click “Reply” on a particular discussion, write your feedback and then click on “Post to forum.”