session 33 practice

An emulsion is a dispersion in which the dispersed phase is miscible with the dispersing phase.

 

True

 

False

False

An emulsifying agent as a third component is required to stabilize emulsions.

 

True

 

False

True

A pharmacist needs to prepare a surfactant blend with a hydrophilic-lipophilic balance value of 9.1.  As one of the components of the blend, she chooses to use Peg-8 stearate (HLB = 11.1).  Which of the following is the MOST LIKELY REASON for her surfactant choice?

 

The pharmacist was using the surfactant as an anti-foaming agent.

 

The pharmacist was preparing a water-in-oil (w/o) emulsion.

 

The pharmacist was preparing a single phase gel.

 

The pharmacist was preparing an oil-in-water (o/w) emulsion

The pharmacist was preparing an oil-in-water (o/w) emulsion

The required HLB value for a stable emulsion is 12.  If Tween 20 (HLB 16.7) and Span 60 (HLB 4.7) are used as the emulsifiers, what percentage of the Span 60 should be used?

 

65%

 

56%

 

39%

 

19%

39%

According to the Stokes equation, the rate of separation of dispersed phase of an emulsion could be reduced by _______ particle size of the dispersed phase ________ difference in density between the phases and reasonably _______ viscosity of the

decreasing; decreasing; increasing

Which of the following emulsion could not go back to homogenous emulsion by shaking?

 

Breaking

 

Coalescence

 

None of them

 

Creaming

Breaking

Similar with emulsion, microemulsion is not a thermodynamically stable system.

 

True

 

False

False

In dry gum method, gum and water are mixed first and then oil is slowly added.

 

True

 

False

False

In the context of emulsions, what does the term 'creaming' refer to?

 

 

The rise or settling of dispersed globules forming a concentrated layer

 

The hardening of the continuous phase

 

The process of mixing two immiscible liquids

 

The complete mixing of two phases

The rise or settling of dispersed globules forming a concentrated layer

Which theory of emulsification proposes that emulsifiers form a film around droplets to prevent coalescence?

 

 

Oriented Wedge Theory

 

Plastic or Interfacial Film Theory

 

Surface Tension Theory

 

Hydrophobic Interaction Theory

Plastic or Interfacial Film Theory

What is an emulsion?

 

 

A mixture of two immiscible liquids where one is dispersed in the other

 

A solution of a gas in a liquid

 

A blend of two soluble liquids

 

A suspension of solid particles in a liquid

A mixture of two immiscible liquids where one is dispersed in the other

What are the two main types of emulsions?

 

 

Hydrophilic and hydrophobic

 

Oil-in-water (O/W) and water-in-oil (W/O)

 

Solid-in-liquid and liquid-in-gas

 

Gas-in-liquid and solid-in-solid

Oil-in-water (O/W) and water-in-oil (W/O)

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

  

 

The emulsifying agent

 

The phase with higher density

 

The phase that forms the globules

 

The phase that surrounds the globules

The phase that forms the globules

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

 

 

To stabilize the emulsion by preventing the separation of phases

 

To act as a flavoring agent

 

To serve as the continuous phase

 

To increase the viscosity of the emulsion

To stabilize the emulsion by preventing the separation of phases

What is the purpose of reducing globule size in an emulsion formulation?

 

 

To increase the stability and reduce the rate of coalescence

 

To decrease the efficacy of the emulsion

 

To enhance the flavor of the emulsion

 

To increase the density difference between phases

To increase the stability and reduce the rate of coalescence