【摘要】 用电位法测定了亚磷酸镍的溶度积常数logK0.首先设计了一个原电池,由半电池铂金-饱和甘汞电极和半电池镍-亚磷酸镍.亚磷酸根组成,测出了不同亚磷酸根离子活度和不同温度下的原电池电动势,扣除了不同温度下饱和甘汞的电极电势,即得到镍-亚磷酸镍.亚磷酸根的电极电势E.用E值通过Nernst方程式计算出亚磷酸镍的溶解、沉淀过程的活度平衡常数logKa,再用Debye-Hückel方程式将logKa与离子强度联系起来,计算出logKd,用logKd-I作图,外推I趋近于零,求得了不同温度下的一组logK0值,当298 K(25℃)时,logK0=-4.33.再用logK0与热力学温度的倒数(1/T)作图,求得了亚磷酸镍溶解、沉淀过程的ΔH和ΔS,分别为-79.734 kJ.mol-1和184.655 J.mol-1.K-1.更多还原

【Abstract】 The measurement of nickel phosphite′s solubility product constant log K0 by electrical potential method is explored.Firstly,a primary cell was designed,which is composed of a half-cell,platinum-saturated calomel electrode,and half-cell nickel-nickel phosphite·phosphite.Different phosphite′s activity and the primary cell′s electromotive force under the conditions of different temperatures are measured,and electrode potential(E) of nickel-nickel phosphite·phosphite is obtained by deducting the saturated calomel electrode potential.Then the activity equilibrium constant log Ka of nickel phosphite′s solubilizing and precipitating process is calculated by means of value E and via Nernst equation.And then,log Ka is connected with ionic strength(I) to calculate log Kd by Debye-Hückel equation.A picture of log Kd-I is worked out,a group of values of log K0 are obtained by extrapolating ionic strength(I) to zero.log K0 is-4.33 when the temperature is 298 K(25 ℃).Again using log K0 and the reciprocal of the thermodynamic temperature(1/T) to work out a picture,the values of ΔH and ΔS in the nickel phosphite′s solubilizing and precipitating process are obtained,which are-79.734 kJ·mol-1 and 184.655 J·mol-1·K-1 respectively.更多还原