Question

uranium in groundwater reacts with naturally occurring calcium phosphate minerals. Given that the uranium solid produced is UO2HPO4 and all calcium goes to Ca2+ and all released phosphate goes to HPO42-.

1. Write the balanced chemical reaction.

Answer 1

Solution:
Generally, calcium phosphate minerals occur in various forms in nature. Here, we can see a few well-known calcium phosphate minerals.
1) Ca₃(PO₄)₂
2) Ca (H₂PO₄)_2
3) CaHPO₄

And, Uranium exists mostly in the form UO₂ (Pitchblende). So, UO₂ in groundwater reacts with those three naturally occurring calcium phosphonate salts to form solid UO₂HPO₄ and releases Ca²⁺ and HPO^4- in water. The corresponding reactions are as follows:

a) UO₂ + Ca₃(PO₄)₂  + 2 H⁺ UO₂HPO₄ + 3 Ca²⁺ + (HPO₄)^2-

b) UO₂ + Ca(H₂PO₄)₂   UO₂HPO₄ + Ca²⁺ + (HPO₄)^2- + 2 H⁺

C) UO₂ + 2 CaHPO₄ UO₂HPO₄ + 2 Ca²⁺ + (HPO₄)^2-