Abstract
Stability constants of ThCl3+ and ThNO3+3, Kc1 and Kc2 were determined electrometrically by means of the pCl-stat in solutions of KNO3, NaClO4 and NaNO3-NaClO4. The results are presented as a function of concentration, ranging from 0.05 to 1.6mole/l at temperatures of 15°, 25° and 35°C.The value of Kc1 increased markedly with decreasing concentration, especially in the range of concentration below 0.5mole/l. For example, whereas Kc1 was 6 and 2.8 (mole/l)-1 respectively at 0.5 and 1mole/l, extrapolation to zero concentration gave a thermodynamic stability constant Ka as high as 37(mole/l)-1.From the value of Ka and its temperature dependence, the free energy and the heat of complex formation were estimated to be -2.14 and nearly zero kcal/mole, respectively. Hence, a value of 7.2 e.u. was derived for the entropy of complex formation.The apparent stability constant of ThCl3+ in a solution of KNO3 was smaller than that in a solution of NaClO4 by an amount of 15 to 50%, depending on the concentration of solution. This discrepancy was explained by assuming the formation of ThNO3+3. The estimated stability constant of ThNO3+3 varied from 4 to 0.75(mole/l)-1 with an increase of concentration from 0 to 1 mole/l.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
