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用pH 测定法研究了在高浓度电解质溶液中氢离子活度系数(Y_(H+))的变化:(1)在氯化物和硝酸盐溶液中Y_(H+)随盐浓度的增高而急剧增大,在4.5摩尔CaCl_2 溶液中Y_(H+)=173,在2.75摩尔La(NO_3)_3溶液中 Y_(H+)=43,但在Li_2SO_4 溶液中 Y_(H+)随SO_4~(2-)浓度的增高而降低;(2)在相同浓度的氯化物或硝酸盐溶液中Y_(H+)大小的次序是La~(3+)>Y~(3+)>Mg~(2+)>Ca~(2+)>Li~+,在相同离子强度的溶液中,Y_(H+)大小的次序是 Li~+>Mg~(2+)>Ca~(2+)>La~(3+)>Y~(3+);(3)在同一金属的氯化物、硝酸盐和硫酸盐溶液中,Y_(H+)大小的次序是Cl~->NO_3~->SO_4~(2-);(4)酸度在10~(-1)～10~(-3)N范围内,Y_(H+)与酸度无关,而与溶液的离子强度和电解质种类有关。
The change of activity coefficient (Y_ (H_)) of hydrogen ions in high concentration electrolyte solution was studied by pH measurement: (1) Y_ (H_) increased sharply with the increase of salt concentration in chloride and nitrate solution , Y_ (H +) = 173 in 4.5mol CaCl_2 solution and Y_ (H +) = 43 in 2.75mol La_ (NO_3) _3 solution, but with increasing SO_4 ~ (2-) concentration in Li_2SO_4 solution (2) The order of Y H (H) in the same concentration of chloride or nitrate solution is La ~ (3 +)> Y ~ (3 +)> Mg ~ (2 +)> Ca ~ The order of Y_ (H +) in the solution with the same ionic strength is Li ~ +> Mg ~ (2 +)> Ca ~ (2 +)> La ~ (3 +)> (3); (3) In the same metal chloride, nitrate and sulfate solution, the order of Y_ (H +) is Cl ~ -> NO_3 ~ -> SO_4 ~ (2 -); In the range of 10 ~ (-1) ~ 10 ~ (-3) N, Y_ (H +) has nothing to do with the acidity, but with the ionic strength of the solution and electrolyte type.