Surfactant Properties and Surface Phenomena

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What is the primary reason for the existence of surface free energy in the surface layer of a liquid?

Because of the unequal intermolecular forces at the surface (correct)
Due to the difference in pressure between the surface and bulk liquid
Because of the zero net force of neighboring molecules at the surface
As a result of the unequal density of the surface and bulk liquid

What is the main difference between surface tension and interfacial tension?

Surface tension is responsible for the shape of droplets, while interfacial tension is responsible for the surface free energy
Surface tension occurs between a liquid and a gas, while interfacial tension occurs between two liquids or a solid and a liquid (correct)
Surface tension is measured using the capillary rise method, while interfacial tension is measured using the ring method
Surface tension occurs between two liquids, while interfacial tension occurs between a liquid and a gas

Why do droplets typically take a spherical shape?

Due to the unequal density of the liquid and its surroundings
Due to the action of external forces, such as gravity
Because of the minimum surface free energy required to form a spherical shape (correct)
As a result of the difference in pressure between the surface and bulk liquid

What is the purpose of using a capillary tube in the capillary rise method?

To determine the surface tension of the liquid (B) Signup and view all the answers

What is the primary advantage of using a wetting agent?

It reduces the contact angle between the liquid and a solid surface (D) Signup and view all the answers

What is the term used to describe the energy required to increase the surface area of a liquid?

Surface free energy (C) Signup and view all the answers

What is the primary factor that influences the solubilization of a substance above the Critical Micelle Concentration?

The number of micelles is directly proportional to the surfactant concentration (D) Signup and view all the answers

What is the role of wetting agents in the process of wetting?

To lower the contact angle between the surface and the wetting liquid (A) Signup and view all the answers

What determines the behavior of a liquid when it comes into contact with a solid surface?

The balance between the forces of attraction of molecules in the liquid and the forces of attraction between the liquid and the solid phases (A) Signup and view all the answers

What is the significance of a contact angle of 0°?

It indicates complete wetting of the solid surface (B) Signup and view all the answers

What is the primary role of adsorption at solid surfaces in the context of detergency?

To facilitate the wetting and spreading of the liquid on the solid surface (C) Signup and view all the answers

What happens when a liquid has a high contact angle with a solid surface?

The liquid forms a single spherical drop on the solid surface (B) Signup and view all the answers

What is the primary purpose of the DuNoüy Ring Method?

To determine the surface tension of a liquid (C) Signup and view all the answers

What is the effect of adsorption on the surface free energy of a system?

It decreases the surface free energy (A) Signup and view all the answers

What is the term used to describe molecules or ions that are preferentially adsorbed at the surface or interface of a liquid?

Surface-active agents (A) Signup and view all the answers

What is the relationship between the contact angle and the surface tension of a liquid?

The contact angle is inversely proportional to the surface tension (C) Signup and view all the answers

What is the purpose of surfactants in a system?

To decrease the surface tension of a liquid (D) Signup and view all the answers

What is the formula used to calculate the surface tension of a liquid using the DuNoüy Ring Method?

𝒚 = 𝑫𝒊𝒂𝒍 𝒓𝒆𝒂𝒅𝒊𝒏𝒈 × 𝑪𝒐𝒓𝒓𝒆𝒄𝒕𝒊𝒐𝒏 𝒇𝒂𝒄𝒕𝒐𝒓 ² × 𝑹𝒊𝒏𝒈 𝒄𝒊𝒓𝒄𝒖𝒎𝒇𝒆𝒓𝒆𝒏𝒄𝒆 (B) Signup and view all the answers