Disodium hydrogen 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 ...
Na
2HAsO
4.7H
2O. The compound consists of a salt and seven molecules of
water of crystallization
In chemistry, water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. In some contexts, water of crystallization i ...
although for simplicity the formula usually omits the water component. The other sodium arsenates are NaH
2AsO
4 and Na
3AsO
4, the latter being called
sodium arsenate
Sodium arsenate is the inorganic compound with the formula Na3AsO4. Related salts are also called sodium arsenate, including Na2HAsO4 ( disodium hydrogen arsenate) and NaH2AsO4 ( sodium dihydrogen arsenate). The trisodium salt is a white or col ...
. Disodium hydrogen arsenate 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 ...
. It is a white, water-soluble solid.
Being a
diprotic
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
acid, its acid-base properties is described by two equilibria:
: + H
2O + H
3O
+ (p''K''
a2 = 6.94)
: + H
2O + H
3O
+ (p''K''
a3 = 11.5)
Related compounds
*
Monopotassium arsenate
Monopotassium arsenate is the inorganic compound with the formula KH2AsO4. A white solid, this salt is used to prepared other arsenic-containing compounds, mainly pesticides. It is prepared by calcining arsenic oxide and potassium nitrate, follo ...
, KH
2AsO
4
References
Arsenates
Sodium compounds
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