Laboratory Handout - Week 4 CH113 (a PDF version can be found here)
MISSION and GOALS
We seek to understand the importance of observation, hypothesis, and revision of hypothesis in the scientific process.
BRIEFING
The goal of science is to devise a rational knowledge base composed of properties and laws that will help us to rationally understand the world around us. The key to the development of this knowledge is the scientific method. It is an iterative process that contains the following steps:
1. Make observations of a systemNote that in all likelihood the observations of step 4 will force you to make revisions on your hypothesis. Once your hypothesis has withstood extensive testing of its predictions, it is presented to others for more testing. Eventually the hypothesis is accepted as a part of the growing rational knowledge base.
2. Produce a hypothesis that explains the observations
3. Make predictions from the hypothesis and devise a test of this prediction
4. Perform the experiment and observe the results
We will use this set of experiments to hone our observation skills and to test our ability to make simple hypotheses.
THE EXPERIMENT
I. The instructor will perform a chemical demonstration. At this time no explanation of the phenomenon will be given.
In your notebook write you observations. After everybody has completed writing their observations, share your observations with other members of the class. Be careful to distinguish among observations, assumptions, and conclusions. Make careful note of any disagreements any of you had in your discussion. Discuss the difference of how you would write these observations in your notebook, versus how they would be written in a formal lab report.
The instructor will now identify the starting materials used in this demonstration. See if you can hypothesize what might have happened.
Watch the demonstration again, trying to understand some of the chemical transformations that are taking place.
II. Repeat the same procedure for the next two demonstrations
III. Observe the simple set up of the two balloons joined by the clamped tubing. In this simple experiment the clamp will be opened and so that air can pass freely between the two balloons. Before opening the clamp, make a prediction about what will happen. Now open the clamp and describe what actually happened. Did you make the right prediction? Can you improve your hypothesis about balloons? Can you think of a new experiment to test the new hypothesis?
IV. One last demonstration will be performed. You are to write up your observations in a few sentences. Make a hypothesis to explain what happened. Can you test your hypothesis?
PRELAB
Describe the scientific method in your own words, being sure to explain the role of observation. Explain the pitfalls of assumptions made while making observations.
For next week, turn in your observations,
hypothesis and proposed test from the last demonstration.