Definition of Mixing: Mixingis the method in which two or more than two substances are combined together.
Types of mixtures-
1) Positive Mixture-When two/more miscible liquids are mixed or soluble solid is dissolved in water, the mixtures are called as positive mixture .e.g. Solution. It is irreversible.
2) Negative Mixture-Two immiscible liquids are mixed or insoluble solids are mixed with water it forms negative mixture. E.g. emulsion, suspension, mixtures. It is reversible.
3) Neutral Mixture-The substances do not have tendency to mix but once mix, don’t separate after mixing. E.g. ointment, paste, cream.
Mechanisms Of Mixing:
1. Connective Mixing: There is bulk movement of groups of particle from one part of powder bed to another. It occupy by inversion of the powder bed by means of blades or paddles.
2. Shear Mixing: When shear force occur it reduces the scale of segregation by thinning of dissimilar layers of a solid particles.
3. Diffusion Mixing: It occur when random motion of particles within a powder bed causes them to change position relative to one another. It produced by any agitation of powder.