Thorium Hydride, ThH4 was observed by Winkler that a heated mixture of thoria and magnesium absorbs hydrogen, and it was supposed that the greyish black product contained ThH2. Matignon, however, obtained the hydride ThH4 by the combination of the metal with hydrogen at a red heat. It is a solid not acted on by water but dissolved by hydrochloric acid with evolution of hydrogen, thus:
ThH4 + 4HCl = ThCl4 + 4H2.
The formula was established by the measurement of the hydrogen evolved from a known weight of hydride. The hydride dissociates when heated, and at 390° C. dissociation is complete under atmospheric pressure. |