Today, I am going to share an awesome science concept ‘Surface Tension’ through a classic science experiment.
If you are in need of science project for your science fair day, then here is the best science activity you can pick to perform on the day.
How to Make Paper Clips Float on Water
Objective: To explore the strength of water molecules and investigate the science concept ‘Surface Tension’.
All the materials you are going to collect on your experiment table in this activity are easily available. Here is the simple supplies list:
1) Paper Clips
2) A transparent glass Bowl
3) Clean Water
4) Tissue Paper
5) A New Pencil attached with Eraser or Craft Stick
Instructions to do Floating Paper Clip Science Experiment
Complete Step By Step Video
Take a clean and transparent glass bowl on your experiment table and fill it with fresh water.
Make sure to fill the glass bowl with water nearer to the top or brim of the bowl. Such that we are making things go easily during the activity.
Also, you need to wash your hands before the experiment but only using water.
Do not use soap when you decide to conduct this activity because soap may tamper the outcome results as it holds its own surface tension properties.
Just to show your children, perform a small step how a paper clip actually does when dropped in water.
So, take a paper clip and simply drop it in to the glass bowl filled with water. And now ask your child to check whether it is sinking or floating in the bowl of water.
Absolutely, the paper clip sinks to the bottom of the bowl because of density differences.
Remove the paper clip out of the bowl to perform the next step. Then, take a tissue paper and cut it in the shape of square. Make sure the size of the cut tissue paper is slightly larger than the paper clip.
Now, gently place the square cut tissue paper into the glass bowl with water. You will observe the tissue paper start floating and reaches to top of the water.
At this point of time, place our paper clip carefully on top of the tissue paper. This is a bit tricky step as there is no balance inside water to hold things in right place.
Hope this helps you to place the experiment clip in right place on tissue paper and does not touch the water surface.
It is time to poke tissue paper and this is the favourite step for children.
Hahaha! Take the pencil with eraser on the other side. Use the eraser side to poke the tissue paper.
But make sure you are not touching the paper clip on the tissue paper while poking it with pencil. You need to poke the tissue paper until it reaches to the bottom.
Here is another trick. Extend a paperclip to create a holder like this.
Now carefully place the paper clip on the holder and dip it slowly in the water. Viola.. your paper clip will float now.
I let my kids to float as many paper clips as possible on the surface of the water.
We even had fun blowing air through straw to make the paperclips move in circular motion while floating on the water.
What you observe here? You will observe the tissue paper sinks but not the paper clip. The paper clip remains on the surface of the water floating. It looks magical but it is not a magic, it is actually the science. Let us learn the science behind this super classic experiment.
Science involved in Floating Paper Clip Science Experiment
Why does paper clips sinks to bottom in water? Generally, paper clips are of metal material and normally sink to bottom when put in water.
Because the metal materials are usually heavy in weight and possess higher density when compared to water. That is the reason, paper clips usually sink to the bottom in water.
However, we can make the paper clips to float on the surface area of water using simple science trick.
The floating paper clip science experiment is all about ‘Surface Tension’. Surface tension is the cohesive nature of liquid surface film due to the attraction between the molecules which tends to the minimum surface area possible.
In this floating paper clip activity, water molecules hold tightly and stay together because of surface tension.
And we are creating “skin” on the water surface which holds water molecules tightly and suspending the paper clip to appear as floating.
Until the water molecules stay together and hold tightly, they can support paper clip to float on water surface.
So, we are creating ideal and right conditions to support the paper clip to float using tissue paper.
Using tissue paper, we are suspending the paper clip on the surface tension of the water and slowly removing the tissue under it.
Actually, the paper clip does not float but it holds up by the cohesive forces of surface tension and appear as floating.
The same science is being used by the tiny insects to walk across the water surface of the lakes.
Here is another awesome experiment that proves surface tension in an educational way. This is an extension activity to floating paper clip science experiment.
Set up the experiment table with a bowl of water. Repeat the same steps of the above activity and make a paper clip float.
Now, dip your finger in a little amount of dish soap and put it on the surface of the water. You will notice the floating paper clip drop to the bottom that means the paper clip sinks to the bottom of the bowl.
Because the soap liquid spreads or pushes away the surface or skin of the water surface to its sides as soon as the soap comes in contact with water.
The soap liquid has a thin layer of surface tension which is less dense than the water surface tension.
That is the reason the soap layer does not hold paper clip anymore and makes it sink.
If you even want to take the experiment further, you can try the same experiment using other steel objects instead of paper clips.
Also, you can replace water with different varieties of juices, milk, etc. and check whether the outcome results are same.
You can try these interesting and related science experiments with water and surface tension:
Chemical Formula of Surface Tension and Water
Surface tension is the nature of liquid molecules to get attracted due to cohesive forces and remain tightly and tends to minimal surface area possible. The chemical formula of surface tension is:
r = 1/2 . F/L
r is surface tension
F represents Force
L represents Length
Water is the major constituent of Earth’s atmosphere with chemical formula, H2O. In chemical formula, H represents hydrogen atoms and 2 says hydrogen atoms in two numbers. Whereas O represents one oxygen atom. Hydrogen atoms are positively charged and oxygen atom is negatively charged. That means, water molecule is a constituent of two hydrogen atoms and one oxygen atom. Water is colorless, tasteless, odorless, and offers no calories.
Water molecule is stable when two positively charged hydrogen atoms bond to one negatively charged atom. There is a slight difference in charges while bonding which is known as dipole. The bond between two water molecules is referred as hydrogen bonding. The water molecules on the surface of water in the bowl attract each other due to cohesive forces and form surface tension on top of it. This surface tension is the reason to hold paper clip on top of water.
When you dip the soap liquid in the water, the surface tension breaks because the thin layer of soap liquid reduces the water surface tension because of existence of non-polar and dipole free bodies. Hence, it is difficult for paper clips to float and sinks to bottom.
Questions to discuss during the Experiment
Asking questions during the experiment helps children to improve their critical thinking skills and encourages them to do wonders in science. Here are a few questions to discuss about the experiment:
1) Why does paper clip floats on water but not on other liquids?
2) Are there any other liquids that hold paper clip to float?
3) What do you think the shape of the paper clip impacts the floating ability?
4) How many paper clips can the water surface tension holds?
5) Is it possible to increase the surface tension of the water naturally?
6) What are the other liquids that show stronger surface tension and good at floating things?
Yes, absolutely you can float a paper clip on water. Paper clips are of steel material which defy the floating physical laws. But surprisingly we can float steel paper clips on the water using surface tension created on top surface area of water. The higher surface tension of water molecules holds the paper clips float on water.
Naturally, paper clips are of heavy weight and sinks in the water container as it shows greater density than water. But when you suspend the paper clip carefully on top of the water surface, it floats amazingly. This is because of surface tension formed due to the cohesive forces between the water molecules. You can find many tricks to make the paper clip float on top of the water surface in a container.
When you drop a paper clip into the water, it sinks to the bottom of the container. But when you drop the paper clip trickily, on top of the water surface, it floats. Because the water molecules stay tightly together by attracting other water molecules and form a strong surface tension due to cohesive forces. This surface tension keeps the paper clip floating on the water surface.
Alcohol is a non-polar liquid body that holds very less surface tension when compared to water. As alcohol is non-polar, it does not form hydrogen bonds. Without hydrogen bonds there is no cohesive forces and no surface tension making the paper clips sink in the water! Hence, it is highly impossible for a paper clip to float on alcohol.
When you add some detergent to the water on which a paper clip is floating, the surface tension of water gets disturbed. Due to the thin layer of soapy liquid of detergent, the surface tension of water breaks. When the surface tension gets disturbed the water molecules loose enough strength to hold the water molecules together. And the water surface area loses its surface tension due to lack of attraction between the water molecules. Finally causes the floating paper clip to sink to the bottom of the bowl containing full of water.
Tooth picks float on water surface because they naturally come with flat surface and made of wood. Flat surfaces do not sink into the water instead float on top of the water surface naturally. Because of their light weight and surface tension of water, the tooth picks float amazingly on top of the water.
Paper clips float on the surface area of the water because of surface tension. Surface tension is the tendency of liquid molecules to attract each other due to cohesive forces. In floating paper clip science experiment, the water molecules on the surface area attract each other and stay tight due to cohesive force. Thus forms the strong surface tension on the top layer of water in the bowl. When you push the paper clip, due to strong force the surface tension breaks and sinks the paper clip float.
Naturally, paper clip is a metal material i.e. steel and stays separated from other paper clips when placed together in a container. However, they become magnetised when we use strong magnets to make the paper clips float. This is because steel easily gets attracted to magnets and becomes slightly magnetic but loses its magnetism soon after you remove the magnet away.
Yes, absolutely we can increase the surface tension of water using salt. Salt is the magical kitchen hold ingredient that surprisingly increases the water surface tension. All you need to do is just add a little amount of salt to the fresh water taken in a container. That’s it! The surface tension of water increases amazingly. You can observe this by doing some surface tension experiments like floating paper clip, magnet paper clip, etc.
Water is an odourless, tasteless, and calorie less inorganic compound that has strong surface tension i.e. 72.8millinewtons (mN) per meter at 20 °C. There are other liquids that show strongest surface tension such as mercury. Whereas alcohol and benzene shows less surface tension compared to water and mercury.
It all depends on the surface tension. You can keep on adding paper clips to the water surface carefully until the surface tension of the water in the container holds. Make sure you are dropping paper clip one after the other carefully on the surface tension of the water. When you drop paper clips one by one, they start sticking to each other because of the forces acting inside the liquid surface area.
Because of higher surface tension on the water, the paper clip is able to float when placed on quizlet. The water molecules stay tightly together and remain closely forming skin of the water surface due to the cohesive forces inside it. This skin of the water surface is nothing but the surface tension which makes paper clips float on the water surface area.
Floating paper clips with magnets is an interesting and exciting science activity using everyday supplies in the home. Here are the instructions to do:
1) Take 5-6 inch long thread and tie it to one end of the paper clip
2) Now glue the other free end of the thread to the immobile object in the home like tables, desks, etc. Whatever you use, you need to perform the experiment near that object only.
3) Place a magnet just above the paper clip and make sure the magnet is not touching the paper clip. Just bring it near to the paper clip.
4) As the paper clip is metal, it gets attracted to the magnet and starts moving towards magnet which seem like the paper clip is floating.
As human body is much stronger and has great gravitational force, it is impossible for them to walk on water surface. Because of these two reasons, the humans overcome the surface tension of water. Whereas the small tiny insects walk across the surface layer of lake water because of string surface tension of water molecules on the lake. As insects are small in size and light in weight cannot overcome the strong surface tension of water. Thus, it is easy for tiny insects to walk across the water.
The densest liquid on Earth’s atmosphere is Mercury or Quick Silver. Mercury is the best known liquid since 3500 years and stays stable at STP i.e. standard conditions of pressure and temperature. In addition, mercury proves to have higher surface tension than water and known as second highest surface tension liquid after water.
Time requires: It just requires 3-5 minutes of your free time. As it is a simple and quick activity, you can even perform it on your busy day during play time as well.
Age Group: Kids of all age group are perfect to investigate this simple science activity. Especially the older kids learn the science concepts in an easy and educational way while having a lot of fun. Kindergarten, elementary, and pre-school children can also perform this activity during their free time and learn about water molecules.
Safety measures: This activity is completely safe as we are not using any single toxic material or substances. The only thing we need consider is paper clips. As paper clips are tiny, there are chances by younger children to keep it inside the mouth. So, adult supervision is mandatory when you perform this activity with toddlers, and kindergarten. It is always suggestible to wear safety goggles and gloves while performing the activity.