SELENIUM HEXAFLUORIDE

Chemical properties

Selenium hexafluoride is a nonflammable, colorless gas. Repulsive odor.

Physical properties

Colorless gas; refractive index 1.895; density 3.25 g/L at -28°C; liquefies at -34.5°C; freezes at -50.8°C; sublimes at -63.8°C; insoluble in water.

The Uses of SELENIUM HEXAFLUORIDE

Selenium hexafluoride is used as a gaseous electric insulator (146). It may be prepared by passing gaseous fluorine over finely divided selenium in a copper vessel. Industrial selenium exposure is common for makers of arc light electrodes, electric rectifiers, and semiconductors.

The Uses of SELENIUM HEXAFLUORIDE

Gaseous electric insulator.

Preparation

Selenium hexafluoride is prepared by passing fluorine gas over finely divided selenium in a copper vessel:
Se + 3F₂ → SeF₆.

Definition

ChEBI: Selenium hexafluoride is a selenium coordination entity.

General Description

SELENIUM HEXAFLUORIDE is a colorless gas used as a electrical insulator. SELENIUM HEXAFLUORIDE is highly toxic by inhalation. When heated to high temperatures SELENIUM HEXAFLUORIDE may decompose to emit toxic fluoride and selenium fumes. Prolonged exposure of the container to fire or intense heat may cause SELENIUM HEXAFLUORIDE to violently rupture or rocket.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

SELENIUM HEXAFLUORIDE is a colorless, poison gas, when heated to decomposition SELENIUM HEXAFLUORIDE emits very toxic fumes containing metallic selenium and selenium fluorides [Lewis, 3rd ed., 1993, p. 1131].

Health Hazard

TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Vapors are extremely irritating and corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.

Fire Hazard

Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.

Safety Profile

Poison by inhalation. When heated to decomposition it emits very toxic fumes of Fand Se. See also SELENIUM COMPOUNDS and FLUORIDES.

Potential Exposure

Selenium hexafluoride, a gas, is utilized as a gaseous electric insulator.

Shipping

Selenium hexafluoride, Hazard Class: 2.3; Labels: 2.3-Poisonous gas, 8-Corrosive material Inhalation, Hazard Zone A. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner.

Incompatibilities

Hydrolyzes very slowly in cold water. Decomposes on heating, producing hydrogen fluoride, fluoride, and selenium. Contact with metal or acid will produce toxic gaseous hydrogen selenide.

Waste Disposal

Return refillable compressed gas cylinders to supplier. If possible, convert selenium compounds to an insoluble form with SO2 before landfill or solidification.