white crystal(s); slightly deliquescent; used in thoriated tungsten filaments and as a reagent for fluoride determination [HAW93] [MER06]
Physical properties
The tetrahydrate is a white crystalline mass; hydgroscopic; decomposes at about 500°C; very soluble in water; soluble in ethanol.
Uses
Thorium nitrate is a reagent for measuring fluorine and for making thoriated tungsten filaments. Thorium nitrate containing 1% cerium nitrate is the impregnating liquid in making incandescent gas mantles.
Preparation
Thorium nitrate is obtained as an intermediate in making thorium metal from monazite sand. Also, the salt is prepared by heating thorium metal or its oxide or hydroxide with nitric acid, followed by evaporation of the solution and crystallization.
Hazard
Thorium nitrate is highly toxic by ingestion and other routes of exposure. The compound also is a radiation hazard.
