The thermal decomposition of ammonium diuranate (ADU) is a complex process that occurs in several steps, depending on the temperature and pressure conditions. Here's a simplified representation:

Overall Reaction:

(NH₄)₂U₂O₇(s) → 2UO₃(s) + 2NH₃(g) + H₂O(g)

Explanation:

* (NH₄)₂U₂O₇(s): Ammonium diuranate (solid)

* UO₃(s): Uranium trioxide (solid)

* NH₃(g): Ammonia (gas)

* H₂O(g): Water (gas)

Step-by-step Decomposition:

1. Dehydration: Initially, ADU loses water molecules upon heating, forming an anhydrous intermediate.

2. Ammonium release: Further heating leads to the release of ammonia gas.

3. Oxidation: The remaining uranium oxide undergoes oxidation to form uranium trioxide.

Note:

* The actual decomposition products and their proportions can vary depending on the temperature and pressure conditions.

* The thermal decomposition of ADU is often used in the production of uranium dioxide (UO₂), a key component of nuclear fuel.

Important Considerations:

* The decomposition process is exothermic and releases heat.

* The reaction can be hazardous due to the release of toxic and flammable gases.

* Proper ventilation and safety precautions are essential during the handling of ADU and its decomposition products.

This is a simplified representation of the complex thermal decomposition of ADU. For a more detailed understanding, you can consult specialized literature on uranium chemistry and nuclear fuel processing.