Glycerin and glycerine are common names for glycerol. It’s a clear, viscous liquid at room temperature and has no odor. Glycerin is widely used in the pharmaceutical industry and it’s a component of many lipids. Glycerin is also highly soluble and is very hygroscopic (absorbs water easily.)
Chemical Properties
The molecular formula of glycerin is C3H5(OH)3, giving it a molecular mass of about 92.1 g per mole (g/mol.) A molecule of glycerin consists of a chain with three carbon atoms such that a hydroxyl group (OH-) is attached to each carbon atom.
Physical Properties
Glycerin has a density of 1.261 g per cubic centimeter (g/cm^3), making it slightly denser than water, which has a density of 1 g/cm^3. It melts at 64.4 degrees F and boils at 554 degrees F.
Synthesis
Glycerin may be synthesized by using a variety of chemical processes such as the saponification of fats. Saponification is the process used to make soap from animal fat and a strong alkali. Fats are composed of triglyerides, which have the molecular formula (ROOC2)3H5 where R is an unspecified chemical group. Sodium hydroxide (NaOH) and water (H20) are added to produce the following reaction: (ROOC2)3H5 + 3NaOH + H20 -> 3(ROOCNa) + C3H5(OH)3 + H2.
Food
Glycerin has several uses in food. Its hygroscopic nature allows it to keep foodstuffs from drying out and it can serve as a food preservative. Glycerin may be used as a filler in low-fat foods and a thickener in liquids. It’s also used as a sugar substitute, especially in foods made for diabetics. Glycerin has the same calories as table sugar but doesn’t raise blood sugar levels as much as table sugar does.
Nitroglycerine
Glycerol is also used to make nitroglycerin, which is an ingredient in products such as cordite, dynamite, gelignite and smokeless gunpowder. It’s also used in aerosol sprays and tablets for the treatment of angina. This preparation is far too diluted to have any explosive properties.
