Soda alum
Encyclopedia
Sodium aluminium sulfate, NaAl(SO4)2·12H2O or Na2SO4·Al2(SO4)3·24H2O, also known as soda alum or sodium alum, is a form of alum
used in the acidity regulator
of food (E521
) as well as in the manufacture of baking powder
. It is also a common mordant
for the preparation of hematoxylin solutions for staining cell nuclei
in histopathology
.
The classical cubic
alum structure is the dodecahydrate
, which is known in mineralogy
as alum-(Na). Two other rare mineral forms are known: mendozite
(undecahydrate) and tamarugite
(hexahydrate).
Alum
Alum is both a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated potassium aluminium sulfate with the formula KAl2.12H2O. The wider class of compounds known as alums have the related empirical formula, AB2.12H2O.-Chemical properties:Alums are...
used in the acidity regulator
Acidity regulator
Acidity regulators, or pH control agents, are food additives added to change or maintain pH . They can be organic or mineral acids, bases, neutralizing agents, or buffering agents....
of food (E521
E number
E numbers are number codes for food additives that have been assessed for use within the European Union . They are commonly found on food labels throughout the European Union. Safety assessment and approval are the responsibility of the European Food Safety Authority...
) as well as in the manufacture of baking powder
Baking powder
Baking powder is a dry chemical leavening agent used to increase the volume and lighten the texture of baked goods such as muffins, cakes, scones and American-style biscuits. Baking powder works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in...
. It is also a common mordant
Mordant
A mordant is a substance used to set dyes on fabrics or tissue sections by forming a coordination complex with the dye which then attaches to the fabric or tissue. It may be used for dyeing fabrics, or for intensifying stains in cell or tissue preparations. The term mordant comes from the Latin...
for the preparation of hematoxylin solutions for staining cell nuclei
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
in histopathology
Histopathology
Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease...
.
The classical cubic
Cubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....
alum structure is the dodecahydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
, which is known in mineralogy
Mineralogy
Mineralogy is the study of chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.-History:Early writing...
as alum-(Na). Two other rare mineral forms are known: mendozite
Mendozite
Mendozite is a sulfate mineral, one of the alum series, with formula NaAl2·11H2O. It is a hydrated form of sodium aluminium sulfate ....
(undecahydrate) and tamarugite
Tamarugite
Tamarugite is a colorless monoclinic sulfate mineral.Also known as lapparentite.-References:*...
(hexahydrate).