Surface Tension & Surfactants

<p>Mercury (A)</p> Signup and view all the answers

<p>1 x 10-6 s (C)</p> Signup and view all the answers

<p>They reduce surface tension. (A)</p> Signup and view all the answers

<p>The work required to increase surface area by 1 m2. (A)</p> Signup and view all the answers

<p>25°C (C)</p> Signup and view all the answers

<p>They are numerically equivalent. (C)</p> Signup and view all the answers

<p>They float on the surface of the liquid. (A)</p> Signup and view all the answers

<p>They prevent phase separation by reducing interfacial free energy. (A)</p> Signup and view all the answers

<p>Sodium dodecyl sulphate (D)</p> Signup and view all the answers

<p>It separates back into distinct oil and water phases. (D)</p> Signup and view all the answers

<p>It facilitates the creation of a stable monolayer. (A)</p> Signup and view all the answers

<p>It creates a charged environment that prevents coalescence. (D)</p> Signup and view all the answers

<p>Interface (B)</p> Signup and view all the answers

<p>They have higher energies and reactivities (B)</p> Signup and view all the answers

<p>Surface tension (A)</p> Signup and view all the answers

<p>The interaction between two liquid phases (B)</p> Signup and view all the answers

<p>Solid surface in air (A)</p> Signup and view all the answers

<p>Excess energy at the surface compared to the bulk (A)</p> Signup and view all the answers

<p>They are more influenced by attraction from neighboring molecules (B)</p> Signup and view all the answers

<p>Gas (D)</p> Signup and view all the answers

<p>They become spherical to minimize surface area. (D)</p> Signup and view all the answers

<p>It creates more fine particles that are harder to handle. (D)</p> Signup and view all the answers

<p>To minimize total free energy. (A)</p> Signup and view all the answers

<p>They are subjected to a net downward pull. (A)</p> Signup and view all the answers

<p>They achieve a balance of forces. (B)</p> Signup and view all the answers

<p>To overcome the cohesive forces holding molecules together. (C)</p> Signup and view all the answers

<p>They endure a higher inward force that creates contraction. (C)</p> Signup and view all the answers

<p>Surface free energy is associated with stable states. (B)</p> Signup and view all the answers

<p>They act as a barrier through steric hindrance or electrostatic repulsion. (C)</p> Signup and view all the answers

<p>Unionized drugs exhibit higher partition coefficients than ionized ones. (D)</p> Signup and view all the answers

<p>Surfactants only contain hydrophilic regions. (B)</p> Signup and view all the answers

<p>The drug's lipophilicity/hydrophilicity. (B)</p> Signup and view all the answers

<p>Solubility is about the maximum concentration, whereas dissolution is the process of a drug dissolving. (C)</p> Signup and view all the answers

<p>Chlorpromazine (A)</p> Signup and view all the answers

<p>Excipients must be pharmaceutically compatible with active ingredients. (D)</p> Signup and view all the answers

<p>Lecithin from egg (A)</p> Signup and view all the answers

The force that holds the surface molecules of a liquid together. It acts like a thin skin that prevents the liquid from spreading easily.

Substances that reduce the surface tension of a liquid.

A material that has a strong attraction to water molecules.

A material that repels water molecules.

The ability of a liquid to spread out on a solid surface.

A transition region where two immiscible phases come into contact. This contact area is like the boundary between the phases.

The tension existing at the boundary between two immiscible liquids. It governs the ability of two liquids to stay separate.

The excess energy that the surface molecules of a liquid possess compared to those in the bulk. This energy is the result of unbalanced forces acting upon surface molecules.

A mixture of two immiscible liquids, where one is dispersed throughout the other.

A mixture of a solid finely dispersed in a liquid.

The process of breaking down a larger droplet into smaller droplets, often achieved by shaking or agitation.

Surface tension (l/v) and surface free energy (o/w) are numerically equivalent. They represent the same property but with different symbols based on the system.

The surface tension of water, or its tendency to minimize surface area, decreases significantly as temperature increases. This makes hot water a better cleaning agent.

A lower surface tension makes hot water a better wetting agent because it can penetrate into pores and fissures instead of bridging them. This is essential for effective cleaning.

The process of reducing the size of liquid droplets or particles in a mixture, increasing the surface area.

The tendency of a liquid to minimize its surface area. This occurs due to the inward pull of surface tension forces, which makes the liquid 'contract' itself.

The process of reducing the particle size of a solid. This increases the surface area and thus the surface free energy.

A system is said to be in a state of minimum free energy when its total free energy is at its lowest possible value. This is a stable and favorable state for a system.

The process of creating an emulsion. This involves increasing the surface area between two immiscible liquids (oil and water, for example).

The state of a system when the rate of molecules leaving the surface to enter the bulk phase is equal to the rate of molecules leaving the bulk to enter the surface.

Molecules at the surface experience a net inward pull due to stronger attractive forces. This pull causes the surface to contract.

The property of a liquid that makes it resist being punctured or broken. This is due to the inward pull of surface tension forces, which makes the liquid 'cohesive'.

Surfactants are molecules that have both a water-loving (hydrophilic) and a water-hating (hydrophobic) part. They are like the bridge between two contrasting worlds (water and oil).

The tendency of a substance to dissolve in another. In pharmaceuticals, it refers to how well a drug dissolves in a solvent.

The process by which a solid substance, like a drug, dissolves in a solvent.

The distribution of a molecule between two immiscible phases (like water and oil), based on its liking for each phase. A drug might favor one phase over the other.

The ratio of the concentration of a substance in two immiscible phases at equilibrium. It determines how much a drug distributes between water and oil.

The ability of a drug molecule to cross cell membranes, especially in the gastrointestinal tract, for absorption. It depends on the drug's characteristics and its ability to partition between different phases.

In pharmaceuticals, these are substances that have surface activity and are used as excipients in medicines. They can affect the properties of the medicine and influence its absorption, distribution, and effectiveness.