Potassium arsenates

Potassium arsenate, K₃AsO₄; dipotassium hydrogen arsenate, K₂HAsO₄; and potassium dihydrogen arsenate, KH₂AsO₄, have been prepared. Their heats of formation are respectively 396.2 Cal., 339.8 Cal., and 234.0 Cal. The last mentioned has a density of 2.851 at ordinary temperatures, and of 2.8675 at 9.2° C. Potassium meta-arsenate, KAsO₃, has a specific heat of 0.1563 between 17° and 99° C.