URANIUM(IV) OXIDE Chemical Properties

Melting point:

2500°C

Density 

10,96 g/cm³

solubility 

insoluble in H2O, dilute acid solutions; soluble in conc acid solutions

form 

brown cubic crystals

color 

brown cubic crystals, crystalline

Resistivity

3.8 × 10*10 (ρ/μΩ.cm)

Water Solubility 

insoluble H2O, dilute acids; soluble conc acids [MER06]

Crystal Structure

Cubic

crystal system

Cube

Space group

Fm3m

Lattice constant

a/nm	b/nm	c/nm	α/o	β/o	γ/o	V/nm3
0.54581	0.54581	0.54581	90	90	90	0.1626

EPA Substance Registry System

Uranium oxide (UO2) (1344-57-6)

Safety Information

RIDADR 

2912

HazardClass 

7

PackingGroup 

III

HS Code 

28441000

URANIUM(IV) OXIDE Usage And Synthesis

Description

Uranium dioxide, also known as yellow cake, has a molecular formula of UO2. It is a black crystal that is insoluble in water. It is a high radiation risk and ignites spontaneously in finely divided form. It is used to pack nuclear fuel rods for nuclear reactors.

Chemical Properties

URANIUM(IV) OXIDE is black crystals. Insoluble inwater; soluble in nitric acid and concentrated sulfuric acid.

Physical properties

Brown to black powder or cubic crystals; density 10.97 g/cm³; Mohs hardness 5.5; melts at 2,827°C; insoluble in water and dilute acids; soluble in concentrated acids.

Uses

URANIUM(IV) OXIDE is a crystalline (or pellet) form is used to pack nuclear fuel rods.

Uses

Used in nuclear power reactors as nuclear-fuel-sintered element containing either natural or enriched uranium.

Preparation

Uranium dioxide occurs in mineral uraninite. Purified oxide may be obtained from uraninite after purification. The commercial material, however, also is recovered from other uranium sources. Uranium dioxide is obtained as an intermediate during production of uranium metal (See Uranium). Uranyl nitrate, UO₂(NO₃)₂, obtained from digesting the mineral uraninite or pitchblende with concentrated nitric acid and separated by solvent extraction, is reduced with hydrogen at high temperatures to yield the dioxide.

Hazard

High radiation risk. Ignites spontaneously in finely divided form.

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