Surface tension is a fascinating phenomenon that is often overlooked. It is the force that allows insects to walk on water, and it is also responsible for the formation of bubbles.
In this article, you will learn about the science behind the interesting force and how to perform simple surface tension experiments to demonstrate its effects.
Surface tension is a powerful force that can have both practical and scientific applications. By understanding the science behind this phenomenon, you can learn how to harness its power.
What Is Surface Tension
Surface tension is a unique phenomenon that causes the surface of the liquid, when in contact with air, to behave like a thin stretchy elastic membrane.
It is the force that allows water to form droplets and bubbles. It is also responsible for the stability of these shapes.
Related: Learn how to Make Homemade Bubbles with this easy bubble recipe!
Remember the little trick where you can make a paper clip float on water? That’s nothing but water surface tension trick at play!
Surface tension is created by the intermolecular forces of the liquid that pull the liquid molecules together. These cohesive forces between the molecules create tension on the surface of the liquid giving rise to unique properties.
The reason this force is visible on the surface alone is quite simple. Within a liquid, the attractive forces experienced by a molecule are cancelled out by the equal forces along opposite directions from the neighbouring molecules.
However, on the surface things get different. There are no liquid molecules above the surface, so the liquid molecules experience a net inward pull, resulting in tension along the surface of the liquid.
Surface Tension Fun Fact: Did you know Basilisk lizard can walk on water? Check out more interesting Weird but True Fun Facts and prepare to be amazed!
Experiment On Surface Tension
The best way to learn something is to get hands-on. These simple and easy science experiments for kids will help your little ones understand what it is and how it can be manipulated.
Pepper and Soap Science Experiment
In the Pepper and Soap experiment, you will observe how surface tension of water can be changed with a common household item like a dish soap.
It doubles up as a wonderful, hands-on hygiene activity for kids that helps them understand how soap helps clean our hands.
This simple experiment for kids allows them to understand surface tension as well as how soap and detergents work.
You will need:
– A shallow bowl of water
– Grounded Pepper/Pepper Flakes
– Liquid Dish Soap
– Toothpick (finger can also be used)
How to do it:
1. Sprinkle pepper flakes on water. Try to sprinkle pepper evenly. The pepper flakes will float on the water surface.
2. Dip the toothpick (or finger) in soap and gently touch the soapy toothpick on the surface of the water near the centre of the bowl.
This will cause the pepper flakes to spread out and float away along the sides away from your finger, making a hole on the surface of the water.
It is almost magical to see pepper floating away with a touch of your soapy finger! While it may appear like magic, there is actually simple science at work in this soap experiment.
The beauty of this experiment is how innately easy it is! It is perfect science experiment for preschoolers as well as older kids.
Science Behind Pepper & Soap Science Experiment
Soap is one of the most common household items, but did you know that it can also be used to reduce the surface tension of water?
The high surface tension of water is created by the cohesive nature of the water molecules. Water molecules are attracted to each other by something called hydrogen bonds.
Hydrogen bonds are formed when the hydrogen atom of one water molecule is attracted to the oxygen atom of another water molecule.
When soap is added to water, it reduces the attraction between the water molecules, resulting in a decrease in surface tension.
Upon coming in contact with the surface of the water, soap affects water’s surface tension reducing the cohesive forces between the water molecules. This causes them to spread apart, making the pepper flakes float away along with it.
Quick Tip: To boost learning, make sure to add in a science joke or two! Not only will they get your kids laughing but also notch up their engagement.
The Magic Milk Experiment
In this cool science experiment, you will add dish soap to milk and observe how it affects the surface tension of milk.
Much like the pepper and soap experiment, it is a simple science experiment for kids that allows them to understand this fascinating phenomenon as well as figure out how soap and detergents work.
You will need:
– A small bowl of milk
– Liquid soap
– Food coloring
– Earbud
How to do it:
1. Pour milk into a small bowl.
2. Add a few drops of food coloring to the milk.
3. Dip the tip of the earbud into the dish soap and gently touch the food coloring floating on the milk’s surface.
As the soap molecules come in contact with milk molecules, their surface tension changes, sending colors swirling and mixing in an amazing way!
Related: For more magical experiments, hop-on to Harry Potter Science Experiments & Activities.
Science Behind Magic Milk Experiment
The surface tension of milk is created by the attractive forces between the milk molecules.
When dish soap touches the surface of the milk, it breaks its surface tension decreasing the cohesive forces between the milk molecules. This causes the molecules to spread apart, taking the food coloring with them.
The Magic Milk Experiment is a great way to learn about surface tension and how soap can be used to reduce it. It’s also a lot of fun to watch the colors spread out!
This mesmerising, colorful science experiment never fails to amaze kids!
Related: Also explore Why Does Wind Blow with this easy kid-friendly guide.
Surface Tension Applications
While surface tension is often discussed with its effects on water, it also has a variety of applications in other areas.
One such application is in the field of medicine. Surface tension can be used to help prevent the spread of bacteria and viruses.
In hospitals, for example, surgeons often use soap to reduce the surface tension of their hands before scrubbing them. This helps to remove any bacteria or viruses that may be present on the skin.
Related: Teach your kids about hygiene the hands-on way with Hygiene Experiments for Kids.
Similarly, detergents are used to lower the surface tension of water to increase its soaking property. Thus, allowing water to be more readily absorbed in the soiled laundry.
Surface tension is also used in the manufacturing process. It is used to coat objects with thin layers of material through a process known as dip coating.
In this process, an object is dipped into a tank of liquid material. The surface tension of the liquid pulls the material up onto the object, creating a thin, even coating.
As you can see, surface tension can have a variety of applications in different fields. In this article, you have learned the science behind it and how to perform simple experiments to demonstrate its effects.
We hope that this article has piqued your child’s interest in STEM and that they will continue to explore the wonderful world of surface tension!