Take Home Lab #6

Take Home Lab #6:  Mean Free Path Activity

Question: What is the average distance between atoms (also known as mean free path)?

Materials: Ruler, target diagram

Procedure: Mean free path is the average distance an atom has to move before colliding with another atom. This is approximately the distance between molecules or atoms. It is usually used when dealing with gases and plasmas. Mean free path is important for understanding temperature and pressure in nuclear chemistry, optics and sound propagation. Mean free path is important when analyzing chemical reactions that involve gases, calculating the conductivity or density of a gas, and working with plasmas such as in fluorescent lightbulb or in a fusion reactor. (See the Wikipedia entry for more details about the applications of mean free path.) Remember that the word mean used in this context means the same thing as average.

                Consider the diagram on the next page in which there are many circles representing atoms or molecules of a gas or plasma in a container.  Measure the distances between 10 of the atoms and their closest neighbors. Take the average of those 10 distances to find the mean free path. Be sure to use centimeters when measuring. One distance has already been marked for you.

Data:

Copy the data table on a separate sheet of paper.

Number	1st Atom	2nd Atom	Distance (cm)
1	A	D
2
3
4
5
6
7
8
9
10
Mean	All	all

Post-Lab Questions:

1. If two of these atoms were very close together, would it have changed your answer very much? Explain.

2. If you were to increase the number of atoms or molecules in this container, how would it change the mean free path? Explain.

3. If you were to increase the size of the container, how would it change the mean free path? Explain.