Monday, 30 June 2014 14:04

## I6-25: DIFFUSION - DISTRIBUTION OF PING PONG BALLS

• ID Code: I6-25
• Purpose: Demonstrate on a macroscopic scale using ping pong balls how random molecular motion causes substances to diffuse.
• Description:
This model consists of a wooden frame with clear plastic covers, about one ping pong ball in width, ten bins at the top and bottom for setting up initial and analyzing final distributions, with several rows of pegs in between. When the horizontal plastic baffle holding the balls at the top is pulled away, balls will drop through the peg array, become randomly scattered, and drop into bins at the bottom.
##### Engagement Suggestions
• Put four orange balls into bin 5 and four white balls into each of bins 3, 4, 6, and 7. Challenge students to predict whether they will keep this same arrangement as they fall. (When the balls reach the bottom, the four orange balls will have become distributed into the white balls.)
##### Background
This shows on a larger scale how random molecular motion causes substances to diffuse. The array of fallen balls will approximate a probability curve; this is an opportunity to introduce statistical concepts in a physical, measurable manner.
• Availability: Available
• #### I6-01 GAS PRESSURE - MODEL

Illustrates the molecular nature of gas pressure Read More
• #### I6-02: NITROGEN DIAMETER AND MEAN FREE PATH

Experimentally determine the diameter of the nitrogen molecule and to determine the order of magnitude of the mean free path Read More
• #### I6-03 EQUIPARTITION OF ENERGY

Demonstrates equipartition of energy Read More
• #### I6-11: BROWNIAN MOTION WITH TV

Demonstrates equipartition of energy Read More
• #### I6-13: AIR TABLE - MODEL OF BROWNIAN MOTION

Simple model of Brownian motion. Read More
• #### I6-21 GAS DIFFUSION - MODEL

Models gas diffusion through a small hole Read More

• #### I6-24: DIFFUSION VELOCITY

Show that the diffusion velocity is proportional to the RMS molecular velocity. Read More
• #### I6-25: DIFFUSION - DISTRIBUTION OF PING PONG BALLS

Demonstrate on a macroscopic scale using ping pong balls how random molecular motion causes substances to diffuse. Read More

• #### I6-32: MOLECULAR MOTION DEMO - RANDOM MOTION IN GASES

Model random molecular motion. Read More

• #### I6-37: MOLECULAR MOTION DEMO - VAN DER WALLS FORCES

Introduce the concept of attractive force between molecules. Read More

• #### I6-40: MOLECULAR MOTION DEMO - SOLIDS

Model the behavior of solids. Read More
• #### I6-41: MOLECULAR MOTION DEMO - LIQUIDS

Model the behavior of liquids. Read More
• #### I6-51 ENTROPY - SORTING MARBLES

Demonstrates that increasing entropy requires less energy than decreasing entropy Read More
• #### I6-52: ENTROPY - FOUR BALLS IN GAS DIFFUSION MODEL

Demonstrate that an ordered state is statistically possible. Read More
• #### I6-61: MAXWELL'S DEMON

Example of a "Maxwell Demon." Read More
• 1