1 g of potassium nitrite is dissolved in 3 g of 10% acetic acid solution, whereto 0.287 g of fine mercury(II) oxide powder is added with stirring. The solution is concentrated by 5 times its volume with a boiling water bath, the beaker is then placed in a refridgerator. 5 ml of ethyl alcohol is added to the mixture with stirring, the mixture is then filtered and washed with some ethanol. The product is dried in a desiccator.
HgO + 5 KNO2 + 2 CH3COOH = K3[Hg(NO2)5] + 2 CH3COOK + H2O
The solution after all of the HgO has reacted
The mixture after refrigeration
The pure product