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Ammonium Persulfate

Ammonium persulfate (NH4)2S2O8 is a white crystalline inorganic compound. It is a white powder-like salt and is highly soluble in water. It has the chemical formula (NH4)2S2O8.

Hugh Marshall prepared this compound for the first time.

Structure and Chemical Formula

Ammonium persulfate is an ionic compound with a +1 charge on the cation and a -2 charge on the anion. Its chemical formula is (NH4)2S2O8 and its structure is as follows.

Ammonium Persulfate Structure
Ammonium Persulfate Structure (Source)

The value of ammonium persulfate molar mass is 228.18 g/mol.

Physical Properties

AppearanceWhite, Crystalline Solid
Molar Mass228.18 g/mol
Density1.98 g/cm³
Melting Point120°C
Solubility80 g/100 mL (25 °C) in water. Moderately soluble in MeOH
Heat Capacity529.7 J/mol/K
OdourMild, Unpleasant Odour

Chemical Properties

  1. The white crystalline compound decomposes in an aqueous medium to form ammonium ions and peroxydisulfate oxyanions. This further decomposes into sulfate ions. Therefore the decomposition of the compound can result in the formation of sulfuric acid fumes.
formation of sulfuric acid fum.
  1. Oxidation of alkynes using ammonium persulfate and diphenyl diselenide as catalyst in aqueous media results in 1,2 dicarbonyl derivatives or hemiacetals (starting from terminal alkynes).
  1. It is a strong and stable oxidising agent.

Production

Ammonium Persulfate can be produced via the electrolysis of ammonium sulfate (NH4)2SO4 and sulfuric acid H2SO4 followed by crystallisation of the electrolytic solution.

The sulfuric acid is electrolysed to hydrogen sulfate ions HSO4⁻ at the anode. 2 hydrogen sulfate ions form peroxydisulfate acid H2S2O8, which reacts with the ammonium sulfate to form ammonium persulfate and sulfuric acid. 

H2SO↔ H⁺ + HSO4

Anode Reaction:

2 HSO4⁻ ─ 2e⁻ → H2S2O8

Cathode Reaction: 

2 H⁺ + 2e⁻ → H2

Reaction of Peroxydisulfate Acid with Ammonium Sulfate:

(NH4)2SO4 + H2S2O8 → (NH4)2S2O8 + H2SO4

The remaining solution is crystallised in order to extract the the required compound (NH4)2S2O8.

Applications of Ammonium Persulfate

Some of the several applications of this inorganic compound includes:

  • Preservative in food products
  • Ingredient in hair bleaches
  • Used in PCBs (printed circuit boards)
  • Used as a general oxidising agent
  • Also used as an initiator in several polymerisation reactions.

Ammonium Persulfate Hazards

(NH4)2S2O8 is an irritant. Inhaling dust containing the compound can irritate the lungs, and in severe cases can also cause asthma

Coming in contact with this compound can irritate eyes and cause skin allergies. High exposure to the compound can lead to fluid build-up in the lungs or “pulmonary edema”, in which case immediate medical supervision is required.

FAQs

What is the chemical formula for Ammonium Persulfate?

Its chemical formula is (NH4)2S2O8.

What is the molar mass of Ammonium Persulfate (NH4)2S2O8?

Its molar mass is 228.18 grams per mole.

More on Inorganic Compounds

Copper Hydroxide (Cu(OH)2)Hydrosulfuric Acid (H2S)
Chlorine Trifluoride (ClF3)Barium Carbonate (BaCO3)
Sodium Sulfate (Na2SO4)Chromic Acid (H2CrO4)

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