(Chemistry for ages 5+)
Water is necessary for the existence all of life on Earth, but what makes it so special? One of the main traits of water that makes it so important is that it is polar. This means that each tiny molecule has a positive side and a negative side, kind of like a magnet.
This makes it so molecules of water tend to “stick” together. Of course, they don’t stick together very hard because you can easily separate water droplets from a glass. This is an important property though, especially for plants that have to move water from their roots in the ground to their leaves.
In plants, water has to move up, against the forces of gravity pushing downwards. Polarity allows the molecules to stick together kind of like a chain, and pull each other up through the fibers of the plant until they reach the highest point.
Are you looking for an easy, rainy-day (or sunny-day) activity? Well, this walking water experiment is a great way to learn more about the properties of water while having some fun mixing colors. It will also show how water is able to move from the lowest point of a plant to the highest. Here is how it is done:
Plastic or a cookie sheet (optional)
- If you would like to avoid some of the mess, lay out some plastic or be sure to set all of your cups on a cookie sheet.
- Fill half of your cups with water. If you are using 3 different food colors use 6 cups, if 4 colors use 8 cups. Be sure the water level in each of the filled cups is equal.
- Add 3-4 drops of one color to each of the water-filled cups (a different color in each cup). Stir the water and food coloring together so you have a nice, colorful liquid.
- Set your cups up for the experiment by placing empty cups between colorful water-filled cups. These can be arranged in a straight line (like in the video), or you can place them in a circle. Either way, be sure there are empty cups between the full cups.
- Fold a segment of paper towel long-ways (or hotdog style) two times if it is a half segment (5.5”x11”- as seen in the video above), or four times if it is a full sheet (11”x11”). Then fold the paper towel in half (hamburger style) one time. Repeat this folding style with additional paper towels until you have enough to connect each water-filled cup with the empty cup(s) next to them. (See video for reference.)
- Once you have folded each of your paper towels, place one end in a water-filled cup and the other end in an empty cup neighbor. If your cups are arranged in a line, the cups on each end will have only one paper towel placed within them. If your cups are arranged in a circle, you will have one more empty cup than in the line arrangement, so each of your cups will have 2 paper towels placed within them.
- Now just wait. You can watch as the colorful water travels up the paper towels and into the neighboring empty cups. Let this experiment work itself all the way to completion, which will likely take several hours. You will know it is complete when all of the water levels are equal.
- Now that the water is finished moving, take note of what you see. What happened to the empty cups? What about the cups that were full? How have the colors changed? What do you notice about the paper towels?
Paper towels are made from trees (or other plant materials like bamboo or sugarcane). This makes them a great model to show how the polarity of water allows it to “climb” upwards through the plant fibers. Food coloring helps show what is happening and how the water stops moving once it reaches equilibrium, or when all of the cups have an even amount of water.