Podcast
Questions and Answers
What is the primary reason for the presence of interfacial tension at the interface between two immiscible liquids?
What is the primary reason for the presence of interfacial tension at the interface between two immiscible liquids?
- Differences in molecular size
- Differences in molecular density
- Differences in molecular hydrogen bonding
- Differences in molecular polarity (correct)
What is the result of a positive spreading coefficient when a liquid is placed on a solid surface?
What is the result of a positive spreading coefficient when a liquid is placed on a solid surface?
- The liquid will form a droplet with a 90-degree contact angle
- The liquid will bead up and have a high contact angle
- The liquid will not interact with the surface at all
- The liquid will spread and have a low contact angle (correct)
What is the primary mechanism by which surfactants reduce interfacial tension between two liquids?
What is the primary mechanism by which surfactants reduce interfacial tension between two liquids?
- Formation of covalent bonds between the liquids
- Formation of hydrogen bonds between the liquids
- Insertion of the hydrophobic tail into one liquid and the hydrophilic head into the other (correct)
- Formation of electrostatic attractions between the liquids
What is the primary application of surfactants in cosmetic formulations?
What is the primary application of surfactants in cosmetic formulations?
What is the primary concern when formulating a topical product for skin application?
What is the primary concern when formulating a topical product for skin application?
What is the primary purpose of displacing air from the surface of sulfur, charcoal, and other powders in pharmaceutical applications?
What is the primary purpose of displacing air from the surface of sulfur, charcoal, and other powders in pharmaceutical applications?
Which of the following is an example of the application of wetting in medicine?
Which of the following is an example of the application of wetting in medicine?
What is the primary role of the spreading coefficient in determining the effectiveness of topical creams and lotions?
What is the primary role of the spreading coefficient in determining the effectiveness of topical creams and lotions?
What is the primary benefit of using surfactants in cosmetic formulations?
What is the primary benefit of using surfactants in cosmetic formulations?
Which of the following is an example of interfacial tension in pharmaceutical applications?
Which of the following is an example of interfacial tension in pharmaceutical applications?
What is the primary location of non-polar molecules in aqueous systems when the concentration of surface active agents exceeds the CMC?
What is the primary location of non-polar molecules in aqueous systems when the concentration of surface active agents exceeds the CMC?
What is the primary function of the hydrophile-lipophile balance (HLB) number?
What is the primary function of the hydrophile-lipophile balance (HLB) number?
What is the effect of increasing the concentration of a surface active agent on the solubility of a slightly soluble substance?
What is the effect of increasing the concentration of a surface active agent on the solubility of a slightly soluble substance?
Why do surfactants protect their hydrophobic groups from the aqueous environment?
Why do surfactants protect their hydrophobic groups from the aqueous environment?
What is the result of the ability of a surfactant to solubilize a drug in an aqueous environment?
What is the result of the ability of a surfactant to solubilize a drug in an aqueous environment?
Study Notes
Interfacial Phenomena
- The boundary between two phases is known as an interface.
- Examples of wetting in pharmacy and medicine:
- Displacing air from powder surfaces to disperse drugs in liquid vehicles.
- Displacing dirt with detergents in wound washing and applying medicinal lotions/sprays to skin and mucous membranes.
Spreading Coefficient
- Lotions, creams, sunscreens, and cosmetics require spreading on the skin to be effective.
- Spreading allows hydrophobic groups to be protected from the aqueous environment.
Effect of Surfactant on Solubility
- The ability of a solution to solubilize a drug increases sharply when the surfactant concentration exceeds the Critical Micelle Concentration (CMC).
- Nonpolar molecules in aqueous systems are located in the hydrocarbon core of the micelle, increasing solubility.
Hydrophile-Lipophile Balance (HLB)
- HLB is a measure of the balance between hydrophobic and hydrophilic portions of a surfactant.
- HLB number is a key factor in determining the properties of a surfactant.
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Description
This quiz covers the concept of interfacial phenomena, including wetting and spreading coefficient, and their applications in pharmacy and medicine.
