Chemical Reactivity cont'd - doe-hdbk-1113-98_reaffirm_2005

DOE-HDBK-1113-98

Module 101 Properties of Uranium

Lesson Plan

Instructor's Notes

The lower oxidation states, UO2 and U3O8, tend to

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be dark brown or black. The higher oxidation states,

UO3 and UO4, are generally orange or yellow,

especially in solution or if water or crystallization

are present (e.g., UO42H2O). Furthermore, the

higher oxides usually flake of more easily and are

usually more soluble in water. Being flaky, they are

more easily inhaled. Being more soluble, they are

more easily absorbed into the body.

Uranyl compounds, such as uranyl nitrate, or

UO2(NO3)2, are chemical forms of uranium that are

often found in solution with water. They are

generally yellow in color and are used in criticality

experiments.

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Uranium reacts readily with air and water. For

example, when uranium is machined, small chips

catch fire from the heat of the machining process.

Shavings placed in water react to produce hydrogen

gas. The surfaces quickly oxidize to a hard black

coating that is at first protective; however, under

adverse conditions, it corrodes and flakes.

Uranium also reacts with hydrogen or tritium gas to

form uranium hydride (UH3). Uranium "beds" are

commonly used to store tritium.