Indicators may be considered as weak acids or weak bases that act like buffers and also exhibit color changes as their degree of dissociation varies with pH. For example, methyl red shows its full alkaline color, yellow, at a pH of about 6 and its full acid color, red, at about pH 4. Dissociation and […]
Elixirs are clear, pleasantly flavored, sweetened hydroalcoholic liquids intended for oral use. The main ingredients in elixirs are ethanol and water but glycerin, sorbitol, propylene glycol, f lavoring agents, preservatives, and syrups are often used in the preparation of the final product. Preparation of Elixirs Elixirs are usually prepared by simple solution with agitation and/or […]
Tinctures are alcoholic or hydroalcoholic solutions prepared from vegetable materials or from chemical substances. They vary in method of preparation, strength of the active ingredient, alcoholic content, and intended use in medicine or pharmacy. When they are prepared from chemical substances (e.g., iodine, thimerosal), tinctures are prepared by simple solution of the chemical agent in […]
The three primary states of matter are solid, liquid, and gas. A fourth state of matter is the liquid crystalline state or mesophase. Liquid crystals (LCs) represent a unique state of matter existing between the ordered solid and disordered liquid states. Structure of Liquid Crystals The two main types of liquid crystals are termed smectic […]