Science at home! Fun homemade experiments for the little ones. Let's learn about the Surface Tension of Water!
Before beginning with the experiments we must first know what the theory is:
Surface Tension of Water:
The surface tension of water is a pretty fun concept that you see every day and that many do not even notice. This is a physical effect that, when the water is at rest, the surface layer of the same causes that some objects that are on it do not sink, but remain afloat.
Let's say that liquids require a certain amount of energy to increase their surface, but it also resists this procedure. In this way, a membrane is created that makes some objects not so easily enter the interior of the water.
Let's do some experiments!
To know how surface tension works, what better than doing it ourselves at home?
Clips that float like a boat !!
In this experiment we can appreciate the Surface Tension when we place some clips in a glass full of water. It will be very fun, you will see that they float and do not sink.
Materials:
- Glass cup
- Water
- Metal Clips
Procedures:
To observe the phenomenon, you must pour the water into the glass until the water level is seen above it, but without spilling. The next thing you should do is try to make sure that the metal clips float through the water and do not sink.
If you throw the clips, they will come with great force and will sink quickly. However, if you put the clip on the glass and slide it then the same will float like a boat. Now, if you push the clips a bit from the surface, the tension will be broken and they will be They will sink like the rest.
What has happened?
Water molecules like to be with other water molecules, it's called cohesion. The cohesion is due to the polar character of the water molecules. Polar means that on the one hand they have a positive charge and on the other negative, that is why they attract each other.
The water molecules that are inside are surrounded by water molecules everywhere, but the molecules on the surface do not have anyone on top, so they cling very strongly to both the sides and the bottoms forming a kind of elastic skin on which the clip is attached. Watch as the skin curls under the clip. This phenomenon due to the cohesion forces between the water molecules is known as surface tension. By the way, have you ever seen one of those insects that walk on water? Well you know that it is due to surface tension.
Milk of colors: experiment and work of art:
With this experiment you will achieve a spectacular color explosion. Do not miss it, we will be very funny and the colors will enchant you.
Materials:
- Whole milk.
- Colorants.
- Soap for dishes-
- A swab for the ears.
Process:
- Put whole milk in a deep dish and wait for it to sit.
- Take a few drops of dyes in the milk.
- Bathe the stick impregnated with soap in the milk.
- Be amazed with the incredible colorful dance.
What has happened?
Milk is for the most part water but it also contains among other fatty products. When you add the dyes they float because they are less dense than the milk but when the soap goes into action, the dyes start to run all over the plate mixing, and writhing, creating a sensational effect.
Two things have happened: the first is that the soap breaks the surface tension of the milk and colors are thrown away from the soap. The second is that soap has a mission to fulfill that is to trap fats. This persecution causes milk to move creating currents and eddies in which the dyes are trapped. When the soap has trapped all the fat, the movement will stop.
Let's continue with the fun !!
The sticks that escape!
We have already had fun experimenting with surface tension on other occasions, for example when we made a steel clip float in water. This time we will learn a little more about this amazing phenomenon using toothpicks.
Materials:
- A deep plate
- A few chopsticks.
- A few drops of soap for the dishes.
Process:
- Place several chopsticks floating in the water.
- Dip a finger in detergent and bring it to the center of the bowl touching the water. Immediately afterwards the chopsticks will be fired towards the edges.
What happen?
The molecules that are on the surface of the water do not have other water molecules on top and can only join their neighbors located horizontally and below. In this case the net force on the sides is annulled and the resultant of the cohesion forces is directed downwards, towards the interior of the liquid (there are no molecules that balance above). The consequence is that the surface of the liquid behaves as if it were an elastic film or membrane in tension, so that a liquid always tends to decrease the surface it occupies.
