Solid phase
- Official name
- Ammonium aluminium sulfate dodecahydrate (phase FE)
- Secondary names
- Ammonium alum; Ammonium aluminium sulphate dodecahydrate; Aluminium ammonium sulfate dodecahydrate; Aluminum ammonium disulfate dodecahydrate; Ammonium aluminum sulfate hydrate; ammonium alum dodecahydrate; Aluminum ammonium sulfate (1:1:2) dodecahydrate; Sulfuric acid, aluminum ammonium salt (2:1:1), dodecahydrate; Al(NH4)(SO4)2.12(H2O); AlH28NO20S2
- CAS number
- 7784-26-1
- Family
- ionic solid
- Class
- normal salt
- Compound type
- sulfate
- Formula
- $(NH_4^+)Al^{3+} \cdot (SO_4^{2-})_2 \bullet 12(H_2O)$
- Chemical formula
- (NH4)Al(SO4)2.12H2O
- Elemental formula
- (N+) H28 (Al3+) S2 O16 (O-)4
- Isotope mixture type
- terrestrial abundance
32.0
- Class
- normal salts (07)
- Type
- hydrated simple normal salts (07.04)
- Phase name
- FE-NH4Al(SO4)2.12H2O
- Phase type
- crystalline
- Crystal system
- unknown
- Crystal class
- unknown
- Crystal class symbol
- unknown
- Crystal spacegroup
- unknown
- Comments
- paraelectric phase
- Molar mass
- 453.33 $g/mol$
- State NTP
- solid
- Phase transitions
-
Phase transition type Other phases Temperature - Pressure solid-solid alpha-(NH4)Al(SO4)2.12H2O above -197°C (76 K) - Phase transitions comments
- paraelectric-ferroelectric phase transition at 76K
- Pure color
- colorless
- Color
- colorless, white
- Diaphaneity
- transparent to translucent