Selenic acid Chemical Properties

Melting point:

58°C

Boiling point:

260°C

Density 

1.407 g/mL at 25 °C

refractive index 

n20/D 1.5174(lit.)

Flash point:

>230 °F

solubility 

Miscible with sulfuric acid. Immiscible with ammonia.

form 

Liquid

pka

4.19±0.10(Predicted)

color 

Colorless

PH

2.74(1 mM solution);1.83(10 mM solution);0.97(100 mM solution)

Water Solubility 

g/100g H2O: 426 (0°C), 567 (20°C), 1328 (30°C) [LAN05]; decomposed by alcohol [HAW93]

Merck 

14,8429

Exposure limits

ACGIH: TWA 0.2 mg/m3
NIOSH: IDLH 1 mg/m3; TWA 0.2 mg/m3

Stability:

Stable, but decomposes on heating. Non-flammable. Incompatible with metals, combustible materials. Hygroscopic.

CAS DataBase Reference

7783-08-6(CAS DataBase Reference)

EPA Substance Registry System

Selenic acid (7783-08-6)

Safety Information

Hazard Codes 

T,N

Risk Statements 

23/24/25-34-50/53-33-23/25-41-38

Safety Statements 

23-26-36/37/39-45-61-60-28-20/21-16

RIDADR 

UN 3264 8/PG 1

WGK Germany 

2

RTECS 

VS6575000

TSCA 

Yes

HazardClass 

8

PackingGroup 

I

HS Code 

2811198090

Hazardous Substances Data

7783-08-6(Hazardous Substances Data)

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ALFA

Selenic acid Usage And Synthesis

Chemical Properties

Anhydrous H2SeO4 forms colorless prismatic or needle-shaped crystals; extremely hygroscopic; the melt tends to supercool. On heating, decomposes into SeO2, O2 and H2O.

Uses

Selenic acid is used as an oxidizing agent. Its derivative sodium selenate is used in the preparation of glass and animal feeds. It acts as an analytical reagent and also used for the preparation of other selenium salts such as gold(III) selenate. Further, it reacts with fluorosulfuric acid to get selenoyl fluoride.

Definition

ChEBI: Selenic acid is a selenium oxoacid. It is a conjugate acid of a hydrogenselenate.

Preparation

SeO2 + H2O2 = H2SeO4
The oxidation is carried out in aqueous solution so that dilute selenic acid solution is obtained first; this may be concentrated to the anhydrous acid by evaporation.

General Description

A white crystalline solid. Very corrosive to skin, eyes and mucous membranes. Corrosive to metal. Toxic by skin absorption and by ingestion.

Air & Water Reactions

Very hygroscopic. Soluble in water.

Reactivity Profile

Selenic acid, LIQUID reacts exothermically with chemical bases (for example: amines and inorganic hydroxides) to form salts. The reactions can generate dangerously large amounts of heat in small spaces. A good oxidizing agent. May oxidize organic matter such as wood, cotton, fiberboard, etc.. Reacts with active metals, including iron and aluminum, and also less active metals, to dissolve the metal and liberate hydrogen and/or toxic gases. Can initiate polymerization in certain classes of organic compounds. Reacts with cyanide salts and compounds to release gaseous hydrogen cyanide. Flammable and/or toxic gases are also often generated with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides, and weak or strong reducing agents. Additional gas-generating reactions occur with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), and even carbonates: the carbon dioxide gas from the last is nontoxic but the heat and spattering from the reaction can be troublesome. May often catalyze (increase the rate) of chemical reactions.

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Safety Profile

Selenium compounds are poisons. A corrosive irritant to skin, eyes, and mucous membranes. When heated to decomposition it emits toxic fumes of Se. See also SELENIUM COMPOUNDS,

Selenic acid(7783-08-6)Related Product Information

• Sodium selenate
• Selenic acid
• Sodium selenite
• SODIUM HYDROGEN SELENITE
• Selenium dioxide
• Sodium selenite pentahydrate
• Selenious acid
• Calcium sulfate dihydrate
• Selenium
• Sodium selenate decahydrate
• Selenic acid strontium salt
• SAMARIUM SELENATE
• Selenic acid disilver(I) salt
• AMMONIUM SELENATE
• Selenic acid magnesium salt
• Selenic acid dithallium(I) salt
• ALUMINUM SELENATE
• Selenic acid cobalt(II) salt