Detergents and Surface Tension

There are some questions that we must have come across in our day-to-day lives. Have you ever encountered a raindrop that does not adhere to any glass panel in a uniform order? What is the speciality of detergent or soap that can wash our clothes much better than normal water? Well, in this subject, we are going to study and analyse all kinds of behaviours regarding surface tension and detergents.

What is Surface Tension? 

All the substances that we find in our surroundings consist of molecules which in turn are formed by the combination of one or more atoms. The substances are usually found in three states such as solid-liquid and gas. solution rigid bodies that do not change their shape and size. This is because the molecules of a solid are bound to each other by strong chemical forces. The chemical bonds between the molecules in liquids are relatively weaker and they can move around each other. all the molecules in the gaseous state are free to move randomly with respect to each other.

Thus surface tension is defined as the attractive force which is applied to the molecules available on the surface of the liquid by the molecules underneath. This inclines to attract into the bulk of the liquid and influences the liquid to imagine the shape consisting of the lowest surface area. Another special characteristic of the molecules in a liquid is their interaction with other molecules nearby them. They can be attracted to the molecules of subsistence which is known as cohesion or can be attracted more strongly to the molecules of other substances which is known as adhesion. If you observe a drop of water you can notice the cohesive force acting strongly to keep it in a round shape. This force of attraction applied by the molecules on the surface is known as surface tension.

Surface Tension of Soap Solution

Soap molecules consist of a long chain of hydrogen and carbon atoms. This is the infrastructure of atoms that enjoy inside water. The other terminal is easily connected with the soap molecule. The molecules of soap surround the water particle. The surface tension of water breaks with the help of the detergent molecules attached to the water molecule at both its ends.

(Image will be Uploaded soon)

The grease particle is moved apart and connected with soap molecules, to be accomplished by a water jet spray. The two terminals of detergent molecules help to break the surface tension of water. This is called hydrophobic. The hydrophobic terminals of the detergent particle are being pushed up to the water surface in an attempt to draw out from the water molecule. This phenomenon helps to weaken the hydrogen bonding of water molecules available at the surface. This destroys the surface tension of water. The soap molecule does not desire to convert into liquid form in a soap and water solution. The molecules which have found their path to the surface destroy their path between the molecules of surface water by raising the hydrophobic ends on the water surface. This phenomenon breaks the water molecules apart from each other.

Detergents

The long chain of hydrocarbons having sodium (Na) or potassium (K) atoms at one end are known to be a special type of sodium salts or potassium salts respectively. The Hydrocarbon part is usually the nonpolar portion that is hydrophobic in nature. and sodium or potassium atoms attached at one end are polar and hydrophilic in nature. The combination of two such distinct characteristics gives a unique property to the molecules of detergents. As when detergents mix with water it decreases the surface tension of water molecules so they are known as surfactants. When a hydrophobic substance such as oil or grease come in contact with detergent molecules then the nonpolar end gas is attached to the grease or oil molecule. This explains why grease or oil molecules get dissolved and removed in detergent or soap water instead of in pure water.

The effect of detergent on surface tension brings a non-adhesive nature to water molecules. It does not stick to the surface of the glass. It happens because of the cohesive force in the water-detergent molecule. The exact thing appears when it comes to washing clothes with water. Water can’t help much to clean the dirt. This is where we need detergent powder. The mixture of detergent and water decreases water’s surface tension. We call detergents and shops surfactants. The surfactants decrease the surface tension and increase the sticking capacity of the things. Water in combination with detergent has the capability of strain through thin fibres of dirty clothes. The detergent solution spreads throughout clothes more easily than water. This is the only reason why water can’t help along with the washing of clothes.

The Surface Tension of Water on Adding Detergent to It.

When detergent is combined with water, it reduces its surface tension. The compounds which help to reduce water’s surface tension are known as surfactants. In this whole phenomenon, the lowered surface tension area can be seen where the surfactant is combined with water. These surfactants can be illustrated as detergents, soaps, emulsifiers, foaming agents, and dispersants. The word “surfactant” is the composite of a surface-active agent.

How Detergent Reduces the Surface Tension of Water?

As we have seen how detergent is acting in the water molecule, we can easily determine that it lowers the surface tension in the water. This phenomenon is caused because of surfactants that reduce the surface tension.

What are the Factors Affecting Surface Tension?

These are the following reasons affecting surface tension

Surfactant- It is the prime factor that helps to reduce surface tension. The surfactants combine with a water molecule and lower its original surface tension.

Chemical additions- It changes the characteristics of surface tension. When some random chemical is mixed with a substance, it changes the surface tension. A surfactant in water is the best example of chemical addition.

Oxidation- It has a direct effect on surface tension. Oxidation is a natural phenomenon that appears when oxygen available in the atmosphere helps to lower the surface tension. The impurities that exist on the surface directly influence the surface tension.

Temperature- This temperature factor initiates a decrease in surface tension. Though surface tension decreases, the molecules inside the solution have become operative, with the hike of temperature turning into zero.

Uses of Surface Tension in Real Life

Some real-life applications of the surface tension are:

• It generates a high surface tension in water. The molecules are combined to create a film on the water surface.

• This film, or the thin layer, is strong enough to embrace light objects like a blade or a pin made of tin.

• Surface tension helps to form water drops without making it into a thin layer.

• It also permits water to pass through roots, stems, thermometers, and in the blood vessels of our body. The pulling effect comes into action when one molecule moves up; it attracts the nearest one.