Sodium aluminium sulfate is the inorganic compound with the chemical formula NaAl(SO4)2·12H2O (sometimes written Na2SO4·Al2(SO4)3·24H2O). Also known as soda alum, sodium alum, or SAS, this white solid is used in the manufacture of baking powder and as a food additive.
Hardness:
3
Density:
1.67 g/cm³
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Characteristics
Cultural
Common Questions
General Info About Alum-(na)
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Physical Properties of Alum-(na)
Colors
Colourless
Hardness
3 , Soft
Density
1.67 g/cm³, Obviously Light Weight
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Chemical Properties of Alum-(na)
Formula
NaAl(SO4)2 · 12H2O
Elements listed
Al, H, Na, O, S
Characteristics of Alum-(na)
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Characteristics of Alum-(na)
Like its potassium analog, sodium aluminum sulfate crystallizes as the dodecahydrate in the classical cubic alum structure. Sodium alum is very soluble in water, and is extremely difficult to purify. In the preparation of this salt, it is preferable to mix the component solutions in the cold, and to evaporate them at a temperature not exceeding 60 °C. 100 parts of water dissolve 110 parts of sodium alum at 0 °C, and 51 parts at 16 °C.
Cultural Significance of Alum-(na)
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Uses of Alum-(na)
In the US, sodium aluminum sulfate is combined with sodium bicarbonate and monocalcium phosphate in typical formulations of double acting baking powder. Sodium alum is also used as an acidity regulator in food, with E number E521. Sodium alum is also a common mordant for the preparation of hematoxylin solutions for staining cell nuclei in histopathology. It is also used as a flocculant in water treatment and disinfection, but its relatively crude, caustic action makes it more suitable for industrial applications.
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