Introduction –

Silver sulfate (Ag2SO4)(Ag_2SO_4) is an important inorganic compound used mainly in COD analysis as a catalyst to improve oxidation of organic matter. It is prepared by reacting silver with strong oxidizing acids such as nitric acid and sulfuric acid. he synthesis of silver sulfate helps in understanding redox reactions, crystal formation, and safe handling of laboratory chemicals.

Objective –

1.To produce silver sulfate for applications such as COD analysis and analytical chemistry.

2.To reduce the overall cost compared to purchasing commercially available silver sulfate directly.

  • 25 g commercial silver sulfate costs ₹11,570
  • 5 g silver gives about 7.2 g silver sulfate
  • Buying 7.2 g commercially costs about ₹3332
  • Lab preparation costs about ₹1700–₹1900
  • Therefore, laboratory synthesis is more economical than direct purchase.

Theory –

Silver is a less reactive metal and it does not react with dilute acids. Hence, concentrated nitric acid is used as an oxidizing agent to convert silver into silver nitrate with evolution of nitrogen oxide gases(Brown colored). The silver nitrate formed then reacts with concentrated sulfuric acid to produce white silver sulfate crystals. The process involves oxidation-reduction reaction and precipitation.

Reactions

Formation of Silver Nitrate

Ag + 2HNO3(conc) =AgNO3 + NO2 + H2O

Formation of Silver Sulfate

2AgNO3 + H2SO4= Ag2SO4 + 2HNO3

Materials Required

  • Silver metal (5 g)
  • Concentrated nitric acid
  • Concentrated sulfuric acid
  • Distilled water

Apparatus Required

  • Beaker
  • Round bottom flask
  • Measuring cylinder
  • Glass rod
  • Funnel and filter paper
  • Heating mantle
  • Gas scrubber setup
  • Wash bottle
  • Clamp stand and tubing

Silver sulphate weight

Atomic mass of silver (Ag) = 107.87 g/mol

Calculate moles of silver =Moles of Ag =4.96/107.87
=0.0459 mol

Use stoichiometry
2Ag = Ag2SO4
Moles of Ag2SO4 = 0.0459/2
= 0.02295mol

Calculate mass of silver sulfate

Molar mass of (Ag2SO4) = 311.8 g/mol
0.02295*311.8
~7.15 g

approximately 7.15 g of silver sulfate can be produced theoretically from 4.96 g of silver.

Procedure –

  1. Setup of Round Bottom Flask and Gas Scrubber
  2. Weighing of Silver Using Weighing Balance
  3. Addition of Concentrated Nitric Acid in Round Bottom Flask
  4. Heating of Flask on Heating Mantle for Dissolution of Silver
  5. Formation of Silver Nitrate Solution Inside Flask
  6. Passage of NO₂ Gas Through Gas Scrubber
  7. Addition of Concentrated Sulfuric Acid in Reaction Flask
  8. Heating of Reaction Mixture for Silver Sulfate Formation
  9. Cooling of Solution in Ice Bath for Crystallization
  10. Filtration of Silver Sulfate Using Funnel and Filter Paper
  11. Washing of Crystals with Distilled Water Using Wash Bottle
  12. Drying of Silver Sulfate on in Hot Air Oven
  13. Collection and Storage of Final Product in Sample Bottle