Sodium Uranate, Na₂UO₄

Sodium Uranate, Na₂UO₄, may be obtained in the amorphous form by heating together urano-uranic oxide and sodium chlorate; or by heating sodium uranyl acetate or carbonate. The crystalline form is produced by adding the green oxide in small quantities to fused sodium chloride, or by dissolving the amorphous form in fused sodium chloride, and allowing crystallisation to take place. It yields reddish-yellow to greenish-yellow prisms or leaflets. The following values for the heat of formation of sodium uranate have been obtained by Mixter:

UO₃ + Na₂O = Na₂UO₄ + 96,100 calories
UO₂ + Na₂O₂ = Na₂UO₄ + 110,900 calories
U₃O₈ + Na₂O₂ + 2Na₂O = 3Na₂UO₄ + 285,100 calories.