Copper(II) phosphate

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Freshly ground copper(II) phosphate intended for use in blue paint

Copper(II) phosphate, or cupric phosphate, is a chemical compound with the formula Cu₃(PO₄)₂. It is a light blue powdery compound that is insoluble in water.

Properties

Chemical

Copper(II) phosphate will react with acids to produce the corresponding copper salt and phosphoric acid.

Physical

Copper(II) phosphate is a light blue, powdery substance that is insoluble in water and ethanol, but soluble in ammonia and mineral acids.

Availability

Copper(II) phosphate is usually unavailable for sale as it has very few applications. It is extremely easy to prepare with OTC chemicals.

Preparation

Freshly precipitated and filtered copper(II) phosphate

Copper(II) phosphate can be prepared by combining copper(II) sulfate and trisodium phosphate in a 3:2 molar ratio.

3CuSO_{4 (aq)} + 2Na₃PO_{4 (aq)} → 2Cu₃(PO₄)_{2 (s)} + 3Na₂SO_{4 (aq)}

A different preparation involves reacting copper carbonate with phosphoric acid:

3 Cu₂CO₃(OH)₂ + 4 H₃PO₄ → 2 Cu₃(PO₄)₂ + 3 CO₂ + 9 H₂O

Monoammonium phosphate also works for this preparation.

Projects

• Copper compounds collection
• Paint pigments
• Copper (II) phosphate can be reduced to copper phosphide, which can be used to isolate phosphorous by heating it: 4Cu₃P₂ → 4Cu₃P + P₄

Safety

Like all copper compounds, copper(II) phosphate is mildly toxic, but since it is insoluble it is less of a concern than soluble compounds.