Qualitative reaction on phosphate ion

Presence of phosphate ions causes the formation of a yellow precipitate.

Scientific name: Qualitative reaction of phosphate ions with silver nitrate solution is demonstrated.

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Safety

Wear eye protection goggles and gloves.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

Na3PO4 + 3AgNO3 → Ag3PO4↓ + 3NaNO3

Step-by-step instruction

  1. Prepare a solution which you want to test on the presence of phosphate ions. For demonstration take a sodium phosphate solution.
  2. Add a few drops of silver nitrate solution. If the solution under study contains phosphate ions the formation of a yellow precipitate is observed.

Scientific background

Qualitative analysis is the determination of the presence of an element in compounds and mixtures without estimation of its amount. Qualitative reactions are one of the most common tools of qualitative analysis. If the sample under study contains ions specific to the qualitative reaction the release of gas bubbles or precipitate formation or color change is expected. This experiment demonstrates one of the ways to detect PO4-3 ions. Sodium phosphate is used for testing qualitative reactions on phosphate ions. When sodium phosphate solution is mixed with the silver nitrate solution it forms a yellow precipitate of silver phosphate

Na3PO4 + 3AgNO3 → Ag3PO4 + 3NaNO3

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Published on 16 April 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst