Unitactivity:Molecules in Motion1

NameDate Pd

UNITActivity:Molecules in Motion1

In a previous activity, you added food coloring to a cup of still water and observed how the food coloring spread. If you did not do this activity, watch closely today as your teacher adds food coloring to room temperature water.

Describe what happened by drawing diagrams representing the beginning, middle, and endof how the food coloring spread.

Beginning:Middle:End:

How do your observations support the idea that water molecules might be made up of tiny moving particles?

3.It takes time for the food coloring to spread through the water. What could we do to speed up this process? What could we do to slow it down?

Explore: With the help of your partners, use droppers to carefully place 1 drop of yellow and 1 drop of blue food coloring into hot and cold water at the same time. Allow the colors to mix on their own as you watch them for a couple of minutes.

Describe what the colors looked like and how they moved and mixed in the cold water. You may choose to draw diagrams to explain.

Describe what the colors looked like and how they moved and mixed in the hot water. You may choose to draw diagrams to explain.

5.What does the speed of the mixing colors tell you about the speed of the molecules in hot and cold water?

6. Prepare two storyboard sequences, one each for the hot water and cold water observations. Construct each storyboard sequence with the same number of frames at the same time intervals.

7.There were several variables in this experiment:

Amount of water in each cup
Type of cup used
Number of drops of food coloring
When the coloring was added to the water

Pick two of these variables and explain why it would be important to keep them constant.

1Adapted from ACS Middle School Chemistry Lesson 1.2