高分子磷酸鉀的陽離子交換率與水溶性的關係

The Relationship Between the Solubility and the Cation Exchangeability of Potassium Polymetaphosphate

呂美芳(Mei-Fang Lu)

《化學》 61年4期 (1972/12) Pp. 154-159

https://doi.org/10.6623/chem.1972021

摘要

難溶性高分子磷酸鉀(KPO_)_n之所以可溶於氯化鋰水溶液，乃因鉀離子與鋰離子發生離子交換而生成(K_(1-x)Li_xPO_3)_n之故。陽離子交換率，x，達0.5時，溶解度突增，但x小於0.5時則極不易溶解於水。溶劑，氯化鋰水溶液之濃度越大，離子交換率也隨之增加，而(KPO_3)_n之對氯化鋰水溶液之溶解度亦同時加大。在本實驗中導出x=(118- 1,000 W_x/CV)/32之公式，以求陽離子交換率，x。試式中，C為滴定所用鹽基之規定濃度，W_x為(K_(1-x)Li_xPO_3)_n之重量，而V爲滴定鹽基的體積。用此特別方法求得之x值，與普通之重量分析法所得x值之趨勢一致，但比後者操作簡單而可更廣泛地求出各種(K_(1-x)Li_xPO_3)_n試料中之種種不同之x值。

並列摘要

The insolnble potassium kurrol's salt, (KPO_3)_n, may be dissolved in aq. LiCl, solution, because the K^+ ion in (KPO_3)_n is ion-exchanged by Li^+ ion which is from aq. LiCl to give (K_(1-x)Li_xPO_3)_n. The solubility increases suddenly as the cation exchangeability, x, reaches 0.5. The salt is very difficult to dissolve at the x value less than 0.5. When the aq. LiCl is concentrated, the cation exchangeability will increase as well as the solubility of (KPO_3)_n does. In this experiment, an equation x=(118-1000 W_x/CV)/32, is derived for calculating x value by CV M pH titration method, where W_x is the weight of (K_(1-x)Li_xPO_3)_n, C the normality of the alkali solution, and V the volume of base used in titration. The procedure is simple and gives good results which are in the same tendency with those obtained by the troublesome and time consuming gravimetric analytical method.