Actinium(III) hydroxide

Actinium(III) hydroxide is a white radioactive solid with the chemical formula of Ac(OH)3.

Preparation
Actinium(III) hydroxide may be formed from soluble actinium salts and alkalis or ammonia water, and the resulting gel is precipitated as the product:
 * Ac3+ + 3 OH− → Ac(OH)3↓

Its solubility is slightly greater than that of lanthanum hydroxide, but it is still insoluble in water.

Chemical properties
Actinium(III) hydroxide is an alkaline hydroxide, it can react with acids to obtain actinium salts:


 * Ac(OH)3 + 3 HNO3 → Ac(NO3)3 + 3 H2O