Identify the compound: The chemical formula CaH4(PO4)2 corresponds most directly to which fertilizer compound in common nomenclature?

Introduction / Context:Superphosphates are described by their dominant phosphate species. The formula CaH4(PO4)2 is another way of writing Ca(H2PO4)2, the monocalcium phosphate that constitutes the active, water-soluble component of triple superphosphate (TSP). Recognizing this mapping is useful when cross-referencing fertilizer labels and chemical formulations.

Given Data / Assumptions:

• CaH4(PO4)2 ≡ Ca(H2PO4)2 (monocalcium phosphate).
• TSP is produced by reacting phosphate rock with phosphoric acid to yield monocalcium phosphate.
• SSP contains monocalcium phosphate plus significant gypsum; TSP is the concentrated form.

Concept / Approach:Because TSP is largely monocalcium phosphate with minimal gypsum, the neat formula Ca(H2PO4)2 is commonly associated with TSP in textbook representations. SSP, while containing the same monocalcium species, also contains 2 CaSO4 equivalents (gypsum), so it is not represented simply by Ca(H2PO4)2. Tricalcium phosphate corresponds to rock phosphate; metaphosphoric acid is a condensed phosphate, not a calcium salt.

Step-by-Step Solution:

Verification / Alternative check:Manufacturing routes and product specifications list TSP as primarily monocalcium phosphate, while SSP is Ca(H2PO4)2 + CaSO4.

Why Other Options Are Wrong:

• SSP: includes substantial gypsum; not represented by the pure monocalcium formula.
• Tricalcium phosphate: Ca3(PO4)2, not Ca(H2PO4)2.
• Metaphosphoric acid: polymeric phosphates without calcium.
• Dicalcium phosphate: CaHPO4, different stoichiometry.

Common Pitfalls:Assuming SSP and TSP are chemically identical; they differ in concentration and associated salts, even though both contain monocalcium phosphate.

Final Answer:Triple superphosphate (monocalcium phosphate rich).