The formula for zinc phosphate hydrate, as derived from the condensed formula provided, is H2O9P2Zn3, which more conventionally represents Zn3(PO4)2·H2O (zinc phosphate monohydrate).
Zinc phosphate hydrate refers to various forms of zinc phosphate that incorporate water molecules within their crystalline structure. While several hydrates exist (e.g., dihydrate, tetrahydrate), the specific condensed formula H2O9P2Zn3 indicates a monohydrate form, meaning there is one molecule of water associated with each formula unit of zinc phosphate.
Understanding the Formula
The condensed chemical formula H2O9P2Zn3 combines all atoms into a single string. To understand it in terms of a hydrate:
- Zn3(PO4)2: This is the anhydrous form of zinc phosphate, consisting of three zinc ions (Zn²⁺) and two phosphate ions (PO₄³⁻). When combined, this gives Zn₃P₂O₈.
- H₂O: This represents one molecule of water.
When one molecule of water (H₂O) is associated with Zn₃P₂O₈, the total atomic count becomes Zn₃P₂O₈H₂O, which can be written as Zn₃P₂O₉H₂ or, alphabetically, H₂O₉P₂Zn₃. This confirms that the given condensed formula corresponds to zinc phosphate monohydrate.
Key Properties of Zinc Phosphate Monohydrate
Understanding the properties of this compound is crucial for its various applications.
| Property | Value |
|---|---|
| Compound Formula | H2O9P2Zn3 (Zn3(PO4)2·H2O) |
| Exact Mass | 401.702 g/mol |
| Monoisotopic Mass | 399.705 g/mol |
| Density | 3.998 g/cm³ (anhydrous basis) |
| Solubility in H₂O | Insoluble |
These properties highlight its stability and insolubility, which are important for its primary uses.
Applications of Zinc Phosphate
Zinc phosphate is a widely used chemical compound, primarily valued for its corrosion-inhibiting properties. Its hydrated forms, including the monohydrate, play a significant role in various industries:
- Anticorrosion Pigment: It is a popular, non-toxic pigment used in anti-corrosive coatings and primers for metals. Its action involves forming a passive layer on metal surfaces, protecting them from oxidation.
- Example: Used in paints for steel structures, automotive bodies, and industrial machinery.
- Dental Cements: In dentistry, zinc phosphate cements are utilized for luting (cementing) crowns, bridges, inlays, and onlays, as well as for cavity lining and temporary fillings.
- Insight: Its insolubility and strength make it suitable for long-lasting dental restorations.
- Adhesives: Certain formulations of zinc phosphate are used in specialized adhesive applications.
- Medical and Pharmaceutical: Research continues into its potential in certain biomedical applications due to its biocompatibility.
Why Hydration Matters
The presence of water molecules in the crystal lattice (hydration) can influence a compound's physical and chemical properties, such as density, solubility, and even reactivity. For zinc phosphate, different hydration states can lead to variations in its performance, particularly in coating applications and cement setting times. The monohydrate form provides a stable and effective compound for these uses.
For further information on zinc phosphate, you can refer to resources like PubChem, which provides extensive chemical data.
