Monday, September 19, 2016

A Simple Activity on Cohesion and Adhesion of water

Travelling water experiment


Can water move on a string? Can we transport water through a string? The following experiment will confirm the answer to the questions above. The concept of the following experiment can be used in our day to day activities.

Materials Required:
Two large plastic cups
Thick cotton string of length 2 ½ feet to 3 feet.
Procedure:
Fill one of the beaker with ¾ full of water.
Soak the thick cotton string in water until it is completely wet.
Put one end of the string into the cup with water and the other end in the empty cup.
Add a little food colour to water in the cup so that we can see water travelling through the string. Raise the cup with water slightly.  Observe.
Observation:
Water will cling to the string. We will see water droplets entering slowly in the empty cup. Water will start collecting in the empty cup drop by drop. The level of water in the cup with water will decrease and the level of water in the empty cup will increase.
Explanation:
Water is a unique substance. It has both strong “cohesive” and “adhesive” properties. This means that water can stick to itself (cohesion) and with other things (adhesion). A water molecule has two hydrogen atoms and one oxygen atom. These atoms end up having positive and negative charges, which cause them to stick to one another. When we soak the string in the water, and the water adheres to it. Even though water may drip, it is still soaked. That is adhesion. When we insert the string in the empty cup, we notice that water clings to other water molecules attached to the string, and we will see a little stream underneath the string. That is cohesion!
Each molecule of water is made up of two hydrogen atoms and one oxygen atom. A drop of water has a many molecules that are held together by electrical, molecular bonds.
In the case of water molecule, the individual molecules of water are held together by hydrogen bond and it is quite strong. These strong hydrogen bonds allow water molecules to stick together very well and move down the string into the bottom of the  cup. When like molecules attract each other, it is called cohesion.
The moistened string help the water molecules stick together and stick to the string. Water molecules can stick to other materials, too. This property of different molecules sticking to each other is called adhesion. In this case, water molecules stick to the string and other water molecules stick to them. 
The concept of this experiment can be made use of while watering plants in our garden. If we adapt this method for watering plants the yield will be more. Water is essential for the plants to grow. The soil where the plants grow should be wet in order to keep the plants growing. By following the method described below water can be supplied to the crops for 24hrs nonstop slowly.










How to provide water to plants 24hrs nonstop?

Step 1: Fill a big drum with water in the garden.

Step 2: Cut many thick cotton ropes of different lengths. Soak them in water.
Step 3: Put them in big drum with water.
Step 4: Take the other end of the cotton ropes and place them near the root of the plants in the garden.
This method of watering the crops is easy and ensures wetness in the soil always. We must see that the big drum has enough water. This method does not consume any fuel or energy. This method of watering the plants can be adapted for kitchen gardens, potted plants that are kept in the portico or balcony and a small garden.
Now the questions are answered…..
Can water move on a string? YES….

Can we transport water through a string? YES……










 

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