Emulsions in Chemistry
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Emulsions in Chemistry

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Questions and Answers

What is one of the main functions of the mixture in emulsions?

  • It provides the proper hydrophilic-lipophilic nature. (correct)
  • It enhances the flavor of the oil phase.
  • It increases the volatility of the product.
  • It reduces the shelf life of the emulsion.
  • Which method involves mixing the emulsifying agent with oil before adding water?

  • Bottle method
  • In Situ soap method
  • Continental or Dry Gum method (correct)
  • Wet gum method
  • What are Tragacanth and agar frequently used for in emulsions?

  • To decrease the overall viscosity of the product
  • To enhance color stability
  • To increase the flavor of the oil phase
  • To thicken the external phase and reduce creaming (correct)
  • What is the correct ratio of oil, water, and emulsifiers in the continental method?

    <p>4:2:1</p> Signup and view all the answers

    What are the two main steps in the preparation of an emulsion?

    <p>Preparation of a primary emulsion and dilution with other substances</p> Signup and view all the answers

    What is the role of the emulsifying agent in an emulsion?

    <p>To prevent the separation of the dispersed phase from the medium.</p> Signup and view all the answers

    Which of the following correctly describes an O/W emulsion?

    <p>It consists of oil droplets dispersed in water.</p> Signup and view all the answers

    What is one advantage of using emulsions over solid dosage forms?

    <p>Emulsions can provide faster absorption.</p> Signup and view all the answers

    What are W/O emulsions primarily used for?

    <p>To mask the oiliness of medicinal oils.</p> Signup and view all the answers

    Which of the following statements about emulsions is true?

    <p>O/W emulsions can be readily removed by washing.</p> Signup and view all the answers

    Which phase in an emulsion is known as the dispersed phase?

    <p>The finely divided droplets of one liquid.</p> Signup and view all the answers

    How do emulsifying agents reduce interfacial tension?

    <p>By forming a physical barrier around droplets.</p> Signup and view all the answers

    What is a common purpose of oral O/W emulsions?

    <p>To improve the absorption of oils.</p> Signup and view all the answers

    What is the primary benefit of reducing the particle size of oil globules in emulsions?

    <p>It enhances the digestibility and absorption of the oil.</p> Signup and view all the answers

    Which type of emulsions are meant for administration via I.V. injection or orally?

    <p>Emulsions for internal use</p> Signup and view all the answers

    What characteristic is NOT ideal for emulsifying agents?

    <p>It should possess strong odor, taste, or color.</p> Signup and view all the answers

    Which of the following is a carbohydrate material that serves as an emulsifying agent?

    <p>Pectin</p> Signup and view all the answers

    What is a disadvantage of using gelatin as an emulsifier?

    <p>The emulsion may become too fluid over time.</p> Signup and view all the answers

    Which type of surfactants are effective at a pH greater than 8?

    <p>Anionic surfactants</p> Signup and view all the answers

    Which of the following substances is primarily used as thickening agents for external o/w emulsions?

    <p>High molecular weight alcohols</p> Signup and view all the answers

    What is the advantage of using a mix of emulsifying agents?

    <p>It provides a more efficient and stable emulsion.</p> Signup and view all the answers

    Study Notes

    Emulsions

    • Biphasic heterogeneous systems containing two immiscible liquids
    • One phase (dispersed) is finely subdivided and distributed as droplets within the other (dispersion medium)
    • Dispersed phase: internal or discontinuous
    • Dispersion medium: external or continuous
    • Emulsifying agents stabilize emulsions by:
      • Preventing particle coalescence
      • Maintaining individual droplet integrity
      • Decreasing interfacial tension between liquids

    Types of Emulsions

    • Oil in water (O/W): Oil is the dispersed phase, water is the dispersion medium
    • Water in oil (W/O): Water is the dispersed phase, oil is the dispersion medium

    Purposes & Advantages of Emulsions

    • Stable and homogeneous mixtures: of immiscible liquids
    • Aqueous phase is easily flavored
    • Oil taste can be masked
    • Faster absorption compared to solid dosage forms
    • Oral O/W emulsions:
      • Mask oil taste (liquid paraffin)
      • Improve oil absorption
    • Semisolid emulsions:
      • O/W (vanishing creams)
      • W/O (cold creams)
      • O/W preferred for ease of application and removal
    • Smaller particle size: makes oils more digestible and absorbable (e.g., mineral oil as cathartic)

    Uses of Emulsions

    • Internal Use (oral or IV injection)
    • External Use (skin or mucous membrane)

    Ideal Emulsifying Agent Characteristics

    • Compatible with other ingredients
    • Stable and non-deteriorating
    • Nontoxic with respect to intended use and dosage
    • Minimal odor, taste, and color
    • Promotes emulsification and maintains emulsion stability

    Types of Emulsifying Agents

    • Carbohydrate materials: acacia, tragacanth, agar, pectin (hydrophilic colloids, O/W emulsions).
    • Protein substances: gelatin, egg yolk (O/W emulsions).
    • High molecular weight alcohols: stearyl alcohol, cetyl alcohol, glyceryl monostearate (thickening agents and stabilizers for O/W emulsions).
    • Wetting agents:
      • Anionic, cationic, or non-ionic
      • Non-ionic: effective pH 3-10
      • Cationic: effective pH 3-7
      • Anionic: require pH greater than 8
    • Finely divided solids: bentonite, magnesium hydroxide, aluminum hydroxide (O/W or W/O depending on mixing order)

    Mixed Emulsifiers

    • Blends of emulsifiers are more efficient for stable emulsions.
    • Benefits:
      • Provide proper hydrophilic-lipophilic balance
      • Establish stable interfacial film
      • Desired consistency to product
      • Tragacanth or agar are frequently combined with acacia in O/W emulsions to increase viscosity and slow creaming.

    Emulsion Preparation Methods

    • Dry Gum Method
      • Emulsifying agent (e.g., acacia) mixed with oil before adding water
      • Also known as the 4:2:1 method (oil:water:emulsifier)
    • Wet Gum Method
      • Emulsifier dispersed in water before adding oil
    • Bottle Method
      • Emulsion formed by shaking ingredients in a closed bottle
    • In Situ (Nascent) Soap Method
      • Soap formed in situ as the emulsifier

    Steps in Emulsion Preparation

    • Primary emulsion: thick, creamy, and stable emulsion (oil, acacia, water)
    • Dilution: addition of other substances

    Methods of Emulsification

    • Continental or Dry Gum Method (4:2:1):
      • External phase (water) added to internal phase (oil mixed with emulsifier)

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    Emulsion Lec 1 (2nd Course) PDF

    Description

    Explore the fascinating world of emulsions, which are biphasic heterogeneous systems containing immiscible liquids. This quiz covers the types of emulsions, their stabilization methods, and the purposes and advantages they offer in various applications. Test your knowledge on oil in water and water in oil mixtures!

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