Tufts OpenCourseware
Author: Fulcrum Institute Development Team


NOTE: The Challenge like the ones you tackle this week are opportunities to assess your understanding of the science you've worked with and to stimulate and extend your thinking. Give each challenge your best shot, writing your ideas in your journal. Before you look at solutions, note areas where you think your understanding is solid and areas where it is fragile. Jot down questions you have.

In the discussion this week, refer to your experience with the Challenge. You might pose a question or dilemma, comment on an idea that intrigued you, or, create an additional Challenge based on this week's science focus. Use the subject line S11Challenge.

A mass of air is contained in such a way that the pressure remains constant as the temperature and the volume change. Here is one way this might be done.

If you heat the container of air, thereby raising its temperature the volume of air will expand while the pressure on the gas [that is exerted by the weight pushing down on the movable piston] will not change.

Here are some data taken from just such a setup.

Temperature (°C) Volume (mL)
0 50
25 55
50 60
75 65
100 70

1. Plot these data with Volume on the vertical axis and Temperature on the horizontal axis.


If you extend the line you have just plotted you’ll find that there is some temperature at which the volume of the air seems to go to zero! What is this temperature? Does this make sense? On a molecular level, what do you imagine happens when the temperature gets this low?

2. What is troubling about the graph shown in part 1 of this question? Explain.