String of Spikes

Want to see how osmosis can cause crystals to form? This String of Spikes experiment shows you how osmosis works not just with water but with something added to the water as well!

String of Spikes

If you remember our previous experiment Growing a Gummy Bear, then you may remember that we learned how osmosis works. Osmosis is the way water tends to move from “wet” places to “drier” places. Now we are going to take our knowledge of osmosis a step further in this string of spikes experiment. We are going to see what happens when the water that is moved by osmosis isn’t plain but has something else dissolved or mixed into it. Before we begin, please take a moment and pin this post to your homeschool science board.

What is osmosis?

As we know from our previous experiment, Growing a Gummy Bear, osmosis is a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane. In simple English, osmosis is the process of water moving from wet to drier places. But what happens when something is in that water? How will this affect osmosis? Let’s find out.

String of Spikes Supplies

What you will need:

journal
pens, pencils, crayons
12 inches of cotton string
baking Soda
2 Plastic or glass cups
water
tablespoon

Result Timing: Two Days

String of Spikes Experiment

What to do:

First, fill the two cups with water.
Next, add one tablespoon of baking soda into each cup.
Then, put one end of the string into one cup and the other end into the other cup.
Next, in your journal, draw a picture of your experiment and label it before. Write down what you think is going to happen; this prediction is called your hypothesis. Let the string and the cups sit for two days.
Do not stir, shake, jiggle or wiggle or do anything else to the cups while you are waiting.
After two days, check on your experiment. What do you see? Draw a picture in your journal and label it after.
Write down any of your observations, or anything that you learned and check to see if your hypothesis was correct.

String of Spikes Experiment in Action

How String of Spikes Experiment Works

The water is attracted to the string because the string is drier than the water. It brings the baking soda with it, gradually soaking higher up on the string. The baking soda collects on the string forming small clumps of spikes.