Lead(II,IV) oxide

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Lead(II,IV) oxide
Minium chunks.jpg
Chunks of lead tetroxide.
Names
IUPAC name
Lead(II,IV) oxide
Preferred IUPAC name
Lead tetroxide
Other names
Dilead(II) lead(IV) oxide
Lead tetraoxide
Minium
Orange lead
Red lead
Triplumbic tetroxide
Properties
Pb3O4
Molar mass 685.6 g/mol
Appearance Orange-reddish solid
Density 8.3 g/cm3
Melting point 500 °C (932 °F; 773 K) (decomposes)
Boiling point Decomposes
Insoluble
Solubility Soluble in glacial acetic acid, hot alkali solution, hydrochloric acid
Insoluble in organic solvents
Vapor pressure 1.3 kPa (at 0 °C)
Thermochemistry
-725 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
630 mg/kg (rat, intraperitoneal)
Related compounds
Related compounds
Lead(II) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Lead(II,IV) oxide, more commonly known as minium, red lead or triplumbic tetroxide or simply lead tetroxide, is a bright orange-reddish crystalline or amorphous oxide of lead, with the chemical formula Pb3O4.

Properties

Chemical

Lead(II,IV) oxide does not dissolve in water and does not hydrolyze. When heated to 500 °C, it decomposes to lead(II) oxide and oxygen.

2 Pb3O4 → 6 PbO + O2

Nitric acid dissolves the lead(II) oxide component, leaving behind the insoluble lead(IV) oxide:

Pb3O4 + 4 HNO3 → PbO2 + 2 Pb(NO3)2 + 2 H2O

Physical

Lead(II,IV) oxide is a deep orange-reddish compound, insoluble in water. It is quite dense, 8.3 g/cm3. It is insoluble in water but soluble in hydrochloric acid.

Availability

Minium can be found as a mineral, but it's rare. Red lead was available in past as a pigment, but since most lead pigments have been phased out in the favor of lead-free ones, it is difficult to be found today. Lead tetroxide can be bought as red lead from US Pigment.

Preparation

Lead(II,IV) oxide is prepared by the calcination of lead(II) oxide in air, at about 450 °C:

6 PbO + O2 → 2 Pb3O4

A less energetic way is by mixing potassium plumbate (which can be obtained by reacting lead dioxide with potassium hydroxide) with lead(II) acetate, yielding yellow insoluble lead(II,IV) oxide monohydrate, Pb3O4·H2O, which can be turned into the anhydrous form by gentle heating:

K2PbO3 + 2 Pb(OCOCH3)2 + 2 H2O → Pb3O4·H2O + 2 KCH3COO + 2 CH3COOH
Pb3O4·H2O → Pb3O4 + H2O

Another method involves the reaction of oxygen with molten lead, at temperatures above 450 °C.[1]

Projects

Handling

Safety

Red lead is soluble in hydrochloric acid, such as gastric acid, and therefore it can be absorbed in the organism easily, making it extremely toxic. It should be handled with proper protection, such as gloves, face mask as well as protection goggles.

Storage

Lead(II,IV) oxide should be stored in closed bottles, with a hazardous chemical label.

Disposal

Minium should be taken to the proper disposal facilities. DO NOT POUR IT DOWN THE DRAIN!

References

  1. Frydlender, J.-H., Rev. Prod. Chim., vol. 50, (1947), p. 40 - 41

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