Question

What is 'Cracking of emulsion'? Describe any four factors responsible for cracking of
emulsion

Answer 1

'Cracking of emulsion':
Cracking means the separation of two layers of dispersed phase and continuous phase, due
to the coalescence of dispersed phase globules which are difficult to redisperse by shaking
Factors responsible for cracking of emulsion.
The following factors results in the cracking of emulsion.
i) Decomposition of the emulsifying agent
ii) Addition of a solvent which dissolves both the phases
iii) High temperature and change in pH.
iv) Addition of opposite types of emulgents
v) Growth of micro – organism
vi) Extensive creaming.
Decomposition of emulsifying agent:
 When acid is added to alkali soap emulsion it causes decomposition of
emulsifying agent & thus leading to cracking of emulsion.
Addition of common solvent:
 Addition of common solvent in which both disperse & continuous phase are
soluble forms one phase system & destroys the emulsion.
 Eg. Turpentine, soft soap & water are soluble in alcohol.
Change in Temperature:
 Increase in temperature leads to reduction in viscosity; encourage creaming thus
leads to cracking. Low temperature causes freezing of water content.
Addition of emulsifying agent of opposite type:
 Soaps of monovalent metal produces o/w emulsion,& Soaps of divalent
metal produces w/o emulsion. But addition of monovalent soap to divalent
soap emulsion &viceversa may leads to cracking.
Growth of microorganism:
Preservative should be present otherwise bacteria may destroy emulsifying agent & cause
cracking.
Extensive creaming.
A creamy emulsion is more liable to crack than the homogenous emulsion. So it is
necessary to take steps to retard creaming as far as possible.