Interfacial tension (IFT) arises from differences between the intermolecular forces at the two liquid surfaces in contact with each other. … Therefore, the surface has excess Gibbs energy relative to the interior of the liquid. Surface tension is the excess energy per unit area (force per unit length; SI unit is Nm-1).
Why interfacial tension is lower than surface tension?
Why is interfacial tension less than surface tension?
So why is surface tension greater than interfacial tension? It comes down to the relative strength of the cohesive forces in the two phases. In the gas phase the cohesive forces are substantially smaller in magnitude that those in the liquid phase. Hence surface tension is greater than interfacial tension.
Why surface tension is higher than interfacial tension?
Cohesive forces are intermolecular forces which causes liquid to resist separation. … The cohesive forces between the molecules are responsible for surface tension. Or, the imbalance of these forces as there are less neighboring molecules on the surface than in the bulk of the liquid.
Why surface tension of a liquid is more than its interfacial tension against another liquid?
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. … Because of the relatively high attraction of water molecules to each other through a web of hydrogen bonds, water has a higher surface tension (72.8 millinewtons (mN) per meter at 20 °C) than most other liquids.
Why is surface tension so strong?
As explained, the cohesive force between the molecules causes surface tension. The stronger the cohesive force, the stronger the surface tension. … Formed bonds are called hydrogen bonds which lead to strong cohesive forces between the water molecules and high surface tension of water.
What causes interfacial tension?
However the main forces involved in interfacial tension are adhesive forces (tension) between the liquid phase of one substance and either a solid, liquid or gas phase of another substance. The interaction occurs at the surfaces of the substances involved, that is at their interfaces.
What is interfacial tension?
Interfacial tension is the force of attraction between the molecules at the interface of two fluids. At the air/liquid interface, this force is often referred to as surface tension.
How is interfacial tension between two liquids determined?
Interfacial tension measurement between two immiscible liquids is based on the pendant drop method where a drop of liquid is formed at the end of the needle tip. In the interfacial tension measurement instead of having air as the surrounding phase, the droplet at the needle tip is immersed in another liquid.
Why does oil have a lower surface tension than water?
Water and oil do not interact due to differences in polarity. Water is a polar molecule, whereas oil is not. Water's polarity gives it a high surface tension. The difference in polarity also makes oil insoluble in water.