Interface is the boundary between two or more phases exist together. Several types of interface can exist depending on whether the two adjacent phases are in solid, liquid or gaseous state. LIQUID INTERFACES : Surface and Interfacial Tensions In the liquid […]
Sedimentation Technique: Equivalent diameter: Stokes’ diameter; frictional drag diameter—a sphere having an equivalent drag force to a particle of the same diameter in the same fluid at the same velocity. Range of analysis: 1 μm to about 200 μm. It […]
Dielectric constant: To properly discuss dipoles and the effects of solvation, one must understand the concept of dielectric constant. Placing a molecule in an electric field is one way to induce a dipole. In a capacitor (condenser), there are two parallel […]
A phase is the part whose physical and chemical properties are completely equal and homogenous. it is separated from other parts of the system by interfaces. A system containing water and its vapor is a two-phase system. An equilibrium mixture […]
Solubility of Liquid in Liquid: Frequently two or more liquids are mixed together in the preparation of pharmaceutical products (e.g. aromatic waters, spirits, elixirs, lotions, sprays, and medicated oils). Liquid–liquid systems can be divided into two categories according to the […]
Solubility of solids in liquids: Factors influencing solubility- Particle size (surface area) of drug particles ↓Particle size → ↑ surface area→ ↑Solubility. Log S/So = 2ϒv/2.303RTr So is the solubility of large particles S is the solubility of fine particles […]
Matter: The definition of Matter is anything that has mass and volume (takes up space). States of matter: Matter exists in one of the three states-solid liquid or gas. Two factors usually determined the state in which matter exist. One is the intensity of […]
SETTLING IN SUSPENSIONS : One aspect of physical stability in pharmaceutical suspensions is concerned with keeping the particles uniformly distributed throughout the dispersion. It possible to prevent settling completely over a prolonged period of time, it is necessary to consider the […]