The chemical equation Cu + 2HgSeO4 -> CuSeO4 + 2Hg

1. Detailed information about the equation Cu + 2HgSeO₄ -> CuSeO₄ + 2Hg
   The above chemical equation describes the reaction process between Copper (Cu) and Mercuric selenate (HgSeO₄) to form Copper selenate (CuSeO₄) and Mercury (Hg).

2. Reaction conditions
   This reaction requires specific temperature and pressure conditions and must occur in an acidic environment.

3. Reaction process
   Initially, Copper reacts with Mercuric selenate to form Copper selenate and Mercury. This reaction is a redox reaction.

4. Phenomena occurring
   During the reaction process, you will see the color of the solution change and gas bubbles may appear due to the reaction. Copper will be oxidized into Copper selenate, while Mercuric selenate will be reduced into Mercury.

Note: As both Copper and Mercury are heavy metals and can cause health issues if not handled properly, this reaction process should be conducted under the supervision of someone with experience and knowledge in chemistry.