Normally we associate rain with the spring season, but with the recent warm winter temperatures in Fargo, we've had some January rain. No matter the season, the cool thing about rainy days is that they are often accompanied by beautiful rainbows!
If you want to learn more about rainbows, click the button below:
Before we try this fun experiment, you need to know a little bit about density.
The density of a given liquid is determined by mass or how closely the molecules in that liquid are packed.
Density does not only exist in liquids, but in all states of matter. The density of a material is its mass per unit volume. What does this mean?
The density equation shows us that density is mass (weight) divided by volume (the amount of space that a substance occupies):
In relation to our project, the density of a liquid is determined by how many molecules of that substance fit into a set volume.
Think about it. Let’s say you put five gummy bears into a Ziploc bag for your little brother and 20 gummy bears into the same size Ziploc bag for yourself. Whose bag of gummy bears is more dense?
A liquid with less molecules or smaller molecules is less dense than a liquid that has more molecules or larger molecules.
Which figure is more dense?
Demonstration: Pour 1/4 cup oil and 1/4 cup water into a glass. Which liquid sinks to the bottom (aka, which liquid is more dense?)
What does this tell you about these two liquids?
This leads us into our activity for the day!
So you know that water is more dense than oil. Now, let’s try this out with a bunch of liquids. By using many liquids of varying densities, you can make a liquid rainbow in a jar!
YOU WILL NEED:
- Mason jar
- 1/4 measuring cup
- Food coloring (several different colors)
- Turkey baster or some form of dropper
- Olive oil
- Corn Syrup
- Dish soap
- Rubbing Alcohol
Here’s what to do!
- The first liquid that you will add to your jar is the honey. Use the 1/4 measuring cup to measure out 1/4 cup of honey, and then pour it into the jar. Make sure you pour it straight into the middle of the jar--be careful not to get it on the sides!
- Rinse out the measuring cup. You will need to do this after each liquid is added.
- After the honey settles into an even layer, add the corn syrup (again, make sure to dump it in the middle without hitting the sides!). If you want your rainbow to be more colorful, mix in a few drops of food coloring with the corn syrup before you add it to the jar.
- Next, measure and add the dish soap.
- After the dish soap settles, measure and add the water. Again, add a few drops of food coloring to the water before adding it to the jar to make your rainbow more colorful! Use a different color than you did for the corn syrup so you can tell the difference.
- Next, you will measure and add the the olive oil.
- Last, you will measure and add the rubbing alcohol. You can use food coloring to color this liquid, as well! But wait! You will need to use the turkey baster or dropper for this one! Add the liquid in very carefully, so it doesn’t mix with the other layers.
- You’re done! You have your very own rainbow in a jar!
- What enabled you to make a liquid rainbow?
- Explain why these liquids didn’t just mix together.
- Were you surprised by your results? Why or why not?
- Draw your liquid rainbow and label each layer to record which liquids are more or less dense.
Try this out with different liquids! See if you can discover densities of other common liquids in your home.
If you need a visual, check out this video of the experiment you just tried! They use even more liquids than we did, so if you need more ideas, this video is a great resource!
Rolph, E., 2007. Double-alaskan-rainbow. File uploaded from Wikimedia Commons on 1/22/2017.
https://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Double-alaskan-rainbow.jpg/1280px-Double-alaskan-rainbow.jpg File used in accordance with Creative Commons Attribution-Share Alike 2.5 Generic License. Image was not changed.
Gopherboy6956, 2009. Fargo Sundogs 2 18 09. File uploaded from Wikimedia Commons on 1/22/2017.
https://upload.wikimedia.org/wikipedia/commons/thumb/8/88/Fargo_Sundogs_2_18_09.jpg/800px-Fargo_Sundogs_2_18_09.jpg Image in the Public Domain.
Kelvinsong, 2013. Artsy density column. File uploaded from Wikimedia Commons on 1/22/2017.
https://en.wikipedia.org/wiki/Density#/media/File:Artsy_density_column.png File used in accordance with the CC Attribution-Share Alike 3.0 Unported. Image was not changed.
Density example created by Maddie Van Beek.
The Sci-Guys, 2013. The Sci-Guys: Science at Home - SE1 - EP5: 12 Layer Liquid Density Tower. Video uploaded from YouTube on 1/22/2017. https://www.youtube.com/watch?v=4EMUsPJtCoc&feature=youtu.be