A.   Light a candle and hold your hand about 5 inches from the side of the flame. Now move your hand about 5 inches above the flame. 

What do you notice?  (Observations)

What is the explanation?

Clarify your understanding... If air were a good conductor, there would be no difference. However, we can also use this demonstration to show that warm rises. As the air molecules are warmed by the flame,  they move more quickly and take up more space. They become less dense and therefore rise above the cooler air molecules.

B.   Repeat the demonstration for a more dramatic result by holding the head of a wooden match about 1 inch to the side of the flame for about ten seconds.  Then move the match to the same distance above the flame.   Record your results, and write an explanation
 

Observations:

Write an explanation:

Compare hot and cold molecules
 

Fill one film canister about * full with ice water and a second one about * full with very hot water. Hold a piece of white paper behind the canisters so that you can see what happens.  Slightly submerge the tip of the medicine dropper and squeeze out 2-3 drops of food coloring to each of the canisters.  What happens? Why?
Observations:
Your explanation:

Clarify your understanding...
Heat causes molecules of water to move more quickly. Therefore the food coloring is more quickly
dispersed throughout the warmer liquid.
 

Moving marbles molecules
 

	Use a small container filled about 2/3 with marbles as illustrated. The marbles represent  molecules.  Go to this link and explore "molecules in action".
Do this... Observations and explanation 1.  Hold the container and shake it minimally,  so that the marbles only vibrate, but do not  move away from one another.         2.  Now add energy by shaking them a bit  more, so that the molecules flow within the container.         3.   Now add even more energy by shaking the container so that the marbles bounce off one another and out of the container.
Clarify your understanding... #1 represents molecules in a solid state, where the molecules are barely vibrating and taking up a minimal amount of space.  #2 represents molecules in a liquid state. The molecules are moving more quickly and taking up a greater amount of space.  #3 represents a change to the gaseous state.  In gas the molecules are moving more rapidly and bounce off one another to take up more and more space.

Stuffing a Box with Crumpled Paper
 

Get two boxes exactly the same size.  Crumple 2 sheets of scrap paper and put them into one box (A).   Crumple 10 sheets of scrap paper and put them in the second box (B). 1.  Compare the volumes of the two boxes.     2.  Compare the denstiy of the two boxes.
Density is a way to compare how much mass is in a certain volume. Measure the mass of each box and paper and calculate the density.   Box   Volume (cm3) Mass (grams) Density (grams/cm3) A          B	Formula for Density

Density Animations

  1. Go to this link and choose the most dense balloon (bottom of the page). 
 

2. Go to this link and observe Dew Drop's balloon.  Answer the question =>

Why is Dew Dropís balloon growing?  Write your answer and use the words density, volume, and temperature in your explanation.

Copyright © 1999 Gallaudet University Laurent Clerc National Deaf Education Center All Rights Reserved Mon Jan 6 05:23:32 2003