Sodium dihydrogen arsenate is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...
NaH
2AsO
4. Related salts are also called sodium arsenate, including Na
2HAsO
4 (
disodium hydrogen arsenate
Disodium hydrogen arsenate is the inorganic compound with the formula Na2HAsO4.7H2O. The compound consists of a salt and seven molecules of water of crystallization although for simplicity the formula usually omits the water component. The other ...
) and NaH
2AsO
4 (sodium dihydrogen arsenate). Sodium dihydrogen arsenate is a colorless solid that is highly toxic.
The salt is the conjugate base of
arsenic acid
Arsenic acid or trihydrogen arsenate is the chemical compound with the formula . More descriptively written as , this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic acid as ...
:
:H
3AsO
4 H
2AsO + H
+ (K
1 = 10
−2.19)
In the laboratory, it is prepared in this way, crystallizing from a hot saturated aqueous solution, where it is highly soluble when hot (75.3 g in 100 mL at 100 °C). It is obtained as the monohydrate.
Upon heating, solid NaH
2AsO
4H
2O, loses water of crystallization and converts to the pyroarsenate salt Na
2H
2As
2O
7.
References
Arsenates
Sodium compounds
{{inorganic-compound-stub