Search results
Results from the WOW.Com Content Network
Arsenic acid is slowly formed when arsenic pentoxide is dissolved in water, and when meta- or pyroarsenic acid (H 4 As 2 O 7) is treated with cold water. Arsenic acid can also be prepared directly from elemental arsenic by moistening it and treating with ozone. 2 As + 3 H 2 O + 5 O 3 → 2 H 3 AsO 4 + 5 O 2
Arsenic forms colorless, odorless, crystalline oxides As 2 O 3 ("white arsenic") and As 2 O 5 which are hygroscopic and readily soluble in water to form acidic solutions. Arsenic(V) acid is a weak acid and the salts are called arsenates, [5] the most common arsenic contamination of groundwater, and a problem that affects
Arsenic contaminated water typically contains arsenous acid and arsenic acid or their derivatives. Their names as "acids" is a formality; these species are not aggressive acids but are merely the soluble forms of arsenic near neutral pH. These compounds are extracted from the underlying rocks that surround the aquifer.
Bioremediation of ground water contaminated with arsenic aims to convert arsenite, the toxic form of arsenic to humans, to arsenate. Arsenate (+5 oxidation state) is the dominant form of arsenic in surface water, while arsenite (+3 oxidation state) is the dominant form in hypoxic to anoxic environments.
The old (but extremely sensitive) Marsh test generates AsH 3 in the presence of arsenic. [4] This procedure, published in 1836 by James Marsh, [18] is based upon treating an As-containing sample of a victim's body (typically the stomach contents) with As-free zinc and dilute sulfuric acid: if the sample contains arsenic, gaseous arsine will ...
In deoxygenated water, with low pe, arsenite species dominate. [16] [17] Depending on the pH, arsenate can be found as trihydrogen arsenate (that is arsenic acid H 3 AsO 4), dihydrogen arsenate (H 2 AsO − 4), hydrogen arsenate (HAsO 2− 4), or arsenate (AsO 3− 4). [18] Trihydrogen arsenate is also known as arsenic acid.
A recent study by the Center for Environmental Health has revealed high levels of arsenic in two brands of bottled water sold by Whole Foods and Walmart.
Arsenic can enter groundwater due to naturally occurring arsenic at deeper levels or from mine workings. Arsenic(III) can be removed from water by a number of methods, oxidation of As III to As V for example with chlorine followed by coagulation with for example iron(III) sulfate. Other methods include ion-exchange and filtration.