Sodium aluminium phosphate

Sodium aluminium phosphate

Names
Other names E541; aluminium sodium salt
Identifiers
Abbreviations	SALP, SAlP
CAS Registry Number	10305-76-7 N
EC number	232-090-4
PubChem	3032541
Properties
Chemical formula	NaH14Al3(PO4)8·4H2O
Molar mass	144.943 g/mol
Appearance	white powder
Odor	odorless
Solubility in water	insoluble
Solubility	soluble in HCl
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Sodium aluminium phosphate (SAlP) describes the inorganic compounds consisting of sodium salts of aluminium phosphates. The most common SAlP has the formula NaH₁₄Al₃(PO₄)₈·4H₂O and Na₃H₁₅Al₂(PO₄)₈.^[1] These materials are prepared by combining alumina, phosphoric acid, and sodium hydroxide.^[2]

In addition to the usual hydrate, an anhydrous SAlP is also known, Na₃H₁₅Al₂(PO₄)₈ (CAS#10279-59-1), referred to as 8:2:3, reflecting the ratio of phosphate to aluminium to sodium. Additionally an SAlP of ill-defined stoichiometry is used (Na_xAl_y(PO₄)_z (CAS# 7785-88-8).^[3]

The acidic sodium aluminium phosphates are used as acids for baking powders for the chemical leavening of baked goods. Upon heating, SAlP combines with the baking soda to give carbon dioxide. Most of its action occurs at baking temperatures, rather than when the dough or batter is mixed at room temperature. SAlPs are advantageous because they impart a neutral flavor.

As a food additive it has the E number E541.^[4][5] Basic sodium aluminium phosphates are also known, e.g., Na₁₅Al₃(PO₄)₈. These species are useful in cheese making.^[2]

References