Welcome back! Sorry for the Delay. Our family had something that I needed to attend to. We are now (hopefully) back on track. I have also adjusted the schedule.
Due to a lack of ethanol (AKA, I didn’t want to go to the liquor store), we have decided to explore density. What a fun time we had!
Definition: Density and dense usually refer to a measure of how much of some entity is within a fixed amount of space.
History: Sometime around 250 b.c., the Greek mathematician Archimedes was given the task of determining whether a craftsman had defrauded the King of Syracuse by replacing some of the gold in the King’s crown with silver. Archimedes thought about the problem while relaxing in a bathing pool. As he entered the pool, he noticed that water spilled over the sides of the pool. Archimedes had a moment of epiphany. He realized that the amount of water that spilled was equal in volume to the space that his body occupied. This fact suddenly provided him with a method for differentiating a mixed silver and gold crown from a pure gold crown. Because a measure of silver occupies more space than an equivalent measure of gold, Archimedes placed the craftsman’s crown and a pure gold crown of equivalent mass in two tubs of water. He found that more water spilled over the sides of the tub when the craftsman’s crown was submerged. It turned out that the craftsman had been defrauding the King! Legend has it that Archimedes was so excited about his discovery that he ran naked through the streets of Sicily shouting "Eureka! Eureka!" (the Greek word for "I have found it!"). Archimedes had used the concept of density to expose the fraud. (Information by Herricks School District)
Related Learning Ideas: Elements of Chemistry.
Learning About Density Websites
American Chemistry Society: Experiment links for demonstrating density.
A Definition of Density: Middle School Level. Includes the formula for density.
Zoom: The Zoom kids explore which object is more dense.
Steve Spangler Science: Density Experiments
- Food Coloring
- Alka Seltzer
- Clean Jar with Lid
I surprised the kids. We made a lava lamp. Well, sort of.
I had to use gel food coloring as that was all that was available; use liquid food coloring. This takes a LOT of oil. Use CHEAP oil. A soda bottle or smaller jar can be used.
Step 1: Fill the jar 3/4 full with oil.
Step 2: Fill the rest of the jar with water.
Note how the oil/water separate. Why does oil float to the top?
Step 3: Add the food coloring. Try to get a darker color.
Step 4: Cut Alka-Seltzer tab into 8 parts. Drop them one-at-a-time into the liquid.
Watch the magic happen!
We turned the jar upside down, over and over. The brown liquid would not mix with the yellow liquid. Why? Oil and water do not mix! Also, food coloring will not mix with the oil.