Lead(II) Oxide
Properties
| State | Solid (powder or crystalline) |
| Color | Red-orange (litharge) or yellow (massicot) |
| Solubility | Slightly soluble in water (0.017 g/L at 20°C); soluble in acids and alkalis (amphoteric) |
| Melting Point | 888°C |
| Boiling Point | 1477°C |
About Lead(II) Oxide
Lead(II) oxide shows up in two crystal forms with the same formula but different colors — red-orange tetragonal litharge and yellow orthorhombic massicot — and the transition between them at around 489 °C makes PbO a textbook example of polymorphism alongside the rutile/anatase split in TiO2. It is also amphoteric: dissolve a sample in HNO3 and you get Pb(NO3)2 and water, dissolve a second sample in concentrated NaOH and you get sodium plumbite Na2[Pb(OH)4]. That dual reactivity puts PbO in the same teaching slot as ZnO and Al2O3 when an instructor needs to demonstrate amphoterism. The compound's commercial weight, however, comes from one application that dwarfs everything else: lead-acid batteries. Roughly 85% of all PbO produced — well over 4 million tonnes per year — goes into the active-material paste smeared onto battery grids. During formation charging, PbO on the positive plate is oxidized to PbO2 and on the negative plate is reduced to spongy Pb metal; the resulting cells still start essentially every gasoline-powered vehicle on the planet and dominate stationary backup power. PbO also gives lead crystal glass (24-30% PbO by weight) its high refractive index of around 1.7 and the brilliant sparkle that distinguishes Waterford-style cut crystal from soda-lime glass. Radiation-shielding glass for X-ray and gamma-ray applications relies on the same heavy-metal absorption.
Where you'll encounter it
If you've ever turned the key on a gasoline car, you've drawn on lead-acid chemistry that started with PbO paste — the red litharge powder cured onto a lead grid, then formation-charged into PbO2 and spongy Pb that swap roles every time the battery cycles. Battery plants making automotive SLI cells hold the litharge-paste mixers to within tight oxidation-state and surface-area specs because the paste density and morphology determine how cleanly the formation charge converts PbO to PbO2 on the positive plate. Lead-crystal glass blowers melting batches with 24-30% PbO get the heavy hand and the sparkling 1.7 refractive index that distinguishes Waterford-style cut crystal from soda-lime glass under tungsten light. Radiation-shielding glass for X-ray rooms uses the same Pb-content trick to attenuate diagnostic-energy photons without going to leaded acrylic.
Common Uses
- Active-material paste precursor for lead-acid battery plates (~85% of global PbO consumption)
- Lead crystal glass production at 24-30% PbO loading for refractive index ~1.7
- Radiation-shielding glass for X-ray rooms and gamma-ray detector windows
- Pottery and ceramic glaze flux at low temperatures (regulated/restricted in food contact)
- Precursor for synthesis of Pb(NO3)2, Pb(OAc)2, and other lead salts
- Polishing compound (jeweler's rouge variants) for optical glass
- Vulcanization accelerator in chlorinated rubber compounds
- Teaching reagent for amphoterism demonstrations alongside ZnO and Al2O3
Safety Information
Toxic. OSHA PEL 50 µg/m3 inorganic lead (8-hr TWA), action level 30 µg/dL whole blood. GHS: H302 (harmful if swallowed), H332 (harmful if inhaled), H360Df (may damage fertility/unborn child), H373 (chronic organ damage via repeated exposure), H410 (very toxic to aquatic life). PbO dust is the dangerous form — inhalation deposits in the alveoli and dissolves into the bloodstream over weeks. Battery-paste manufacturing facilities operate under OSHA 29 CFR 1910.1025 with respirators, full-face shields, and biological monitoring. Children under six are the most at-risk population for any environmental release.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.