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level: Level 4

Questions and Answers List

EMULSIONS

Question	Answer
a system consisting of two immiscible liquid phases, one of which is dispersed throughout the other in the form of fine droplets.	emulsion
is necessary to stabilize the emulsion	A third component, the emulsifying agent
Following are tests carried out for evaluation of emulsions	1 Determination of particle size and particle count 2 Determination of viscosity 3 Determination of phase separation 4 Determination of electrophoretic properties 5 Electrical conductivity
Particle Size and Particle count is performed by:	1 Optical microscopy 2 Sedimentation by using Andreason apparatus 3 Sedimentation by coulter apparatus
Viscocity is performed by	Cone and plate viscometer
may be observed visually or by measuring the volume of the separated phases.	Phase separation
useful for assessing flocculation since electrical charges on particles influence the rate of flocculation. o/w emulsion having a fine particle size will exhibit low resistance but if the particle size increase, then it indicates a sign of oil droplet aggregation and instability	Electrophoretic Properties
It is determined by using platinum electrodes (diameter 0.4 mm, distance 4mm) micro amperometrically to produce a current of 15 to 50mA	ELECTRICAL CONDUCTIVITY
1 Stable o/w emulsion offer __ resistance, but droplet aggregation __ resistance. 2 A stable w/o emulsion does not conduct electrodes, but with __ conductivity increases	1 less, increases 2 droplet coagulation