The solubility and solubility product of europium trifluoride were measured by radiometric, potentiometric and conductometric
methods. There are significant differences in the values of both solubility and solubility product obtained by the three different
techniques. Due to reasons discussed in the text, radiometric values seem to be more acceptable than the others. The thermodynamic
functions such as ΔH0, ΔG0 and ΔS0 for the dissolution process were also measured. The positive values of ΔH0 and ΔG0 and the negative value of ΔS0 are indicative of the slight solubility of EuF3. The dependence of solubility on pH and also on the fluoride concentration has also been studied. It was confirmed that europium
forms a monofoluoride complex in aqueous solution. The stability constant of this complex was estimated.