Learning Objectives:

• Learn to apply the scientific method
• Learn about experimental design
• Practice the terminology used in scientific studies
• Derive a theory from a scientific study

In this lab, you will practice using the scientific method by designing a series of experiments.  First, you will explore how the rate of diffusion is affected by the medium of diffusion.  Specifically, you will be comparing the rate of diffusion in a solid vs. a liquid medium.  Next, you will explore how temperature affects the rate of diffusion in water.

You will use the scientific method to approach each situation, by formulating a hypothesis, designing an experiment, and predicting your results.  Next, you will perform the experiment, collect your data, and summarize the results of your experiment.  Finally, you will decide whether to accept or reject your hypothesis and derive a theory.  

• Read the lab before coming to class.  The expectation at Chamberlain (CCN/CU) is that you come to class fully prepared for lab.
• Always dress properly for lab.  Be sure to wear closed toed shoes and long pants to lab.  In lab, wear your safety equipment including goggles, lab coat, and gloves.
• Always check with your instructor regarding proper waste disposal
• Listen carefully  to the professor’s instructions and work safely
• Always follow the rules outlined in the safety contract
• If in doubt of how to use a piece of lab equipment, as you instructor.  Improper use of lab equipment can be dangerous or could damage lab materials.
• If you have any safety concerns, see your instructor.
• Use deionized water (DI water) in your experiments

Exploration 1: Explore the Effect of the Physical Medium on Diffusion.

Part 1A:  Experimental Design and Preparation

1. What is the objective of your study?
2. Clearly state your hypothesis.
3. Design an experiment in order to test your hypothesis.  Be sure to identify your independent and dependent variable as well as any controls
4. What experimental results would confirm your hypothesis?
5. Based on the theoretical results above, what is your theory?

Part 1B: Performing the Experiment

1. Graph the diameter for each medium on the same plot (use a line plot).  The independent variable should go on the x axis and the dependent variable should go on the Y axis.
2. Based on the above data, which medium showed a greater rate of movement for the Red 40 dye?
3. Does your data support the hypothesis?  If not, what potential reasons can you identify?
4. Summarize the results of your experiment.
5. Based on these results, what theory could you generate?
6. Peer review is an important part of the scientific process.  Compare your results with the results of other groups.  State the pattern that you noticed.

Exploration 2: Explore how Temperature Effects Diffusion.

Part 2A:  Experimental Design and Preparation

1. What is the objective of your study?
2. Clearly state your hypothesis.
3. Design an experiment in order to test your hypothesis.  Be sure to identify your independent and dependent variable as well as any controls.
4. What experimental results would confirm your hypothesis?
5. Based on the theoretical results above, what is your theory?

Part 2B: Performing the Experiment

1. Based on the above data, does temperature appear to effect the rate of Red 40 dye diffusion?
2. Does your data support the hypothesis?  If not, what potential reasons can you identify?
3. Summarize the results of your experiment.
4. Based on these results, what theory could you generate?
5. Peer review is an important part of the scientific process.  Compare your results with other groups.  State the pattern that you noticed.

Reflection:  

What did you learn from this lab?  Do you feel that the experiments you performed are sufficient to fully study the effects of temperature and physical medium on the rate of diffusion?  What refinements might you make to your experiments given a large budget and time?  Finally, why is peer review so important in the scientific process?  Your response should be of sufficient length to answer all questions fully (Typically 10-14 sentences).