NaHCO_(3)溶液浓度改变引起的支配质子转移反应变化:从HCO_(3)^(-)质子自递反应到HCO_(3)^(-)水解反应  

Shift of the Dominant Proton Transfer Reaction from Autoprotolysis of HCO_(3)^(-)to Hydrolysis of HCO_(3)^(-)Caused by Concentration Change of the NaHCO_(3)Solution

作　　者：柳青 刘建宇[2] 王海水[2] Qing Liu;Jianyu Liu;Haishui Wang(Analytical and Testing Center,South China University of Technology,Guangzhou 510640,China.;School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,China.)

机构地区：[1]华南理工大学分析测试中心,广州510640 [2]华南理工大学化学与化工学院,广州510640

出　　处：《大学化学》2024年第1期305-308,共4页University Chemistry

基　　金：国家自然科学基金(21773072);华南理工大学教研教改项目(C9233073)。

摘　　要：NaHCO_(3)水溶液中存在多个质子转移反应和多重化学平衡。随溶液浓度改变,各质子反应所占的相对比重将发生变化,与质子转移相关的产物H_(2)CO_(3)、H^(+)、OH^(-)和CO_(3)^(2-)的相对含量也会发生变化。绘制了[H_(2)CO_(3)]、[H^(+)]、[OH^(-)]和[CO_(3)^(2-)]随溶液浓度c变化的动态图。从动态图上,可以直观地观察到哪些酸碱组分是主要组分,哪些组分是次要组分。较浓溶液中,[H_(2)CO_(3)]≈[CO_(3)^(2-)]>>[OH^(-)]>>[H^(+)],表明能够产生H^(+)或OH^(-)的质子反应占据次要地位,质子反应HCO_(3)^(-)+HCO_(3)^(-)-H_(2)CO_(3)+CO_(3)^(2-)占据支配地位。9.1×10^(-6) mol-L^(-1)溶液中,[OH^(-)]≈[H_(2)CO_(3)]>>[H^(+)]≈[CO_(3)^(2-)],表明质子反应H_(2)O+HCO_(3)^(-)-H_(2)CO_(3)+OH^(-)占据支配地位。极稀溶液中,[OH^(-)]≈[H^(+)]>>[H_(2)CO_(3)]>[CO_(3)^(2-)],表明H_(2)O-H^(+)+OH^(-)占据支配地位。溶液的酸碱性质主要由起支配作用的质子转移反应控制。There are several proton transfer reactions and multiple chemical equilibria in NaHCO_(3)aqueous solution.As the concentration of the solution changes,the contents of H_(2)CO_(3),H^(+),OH^(-)and CO_(3)^(2-),which are related to proton transfer reactions,also change.The diagram of[H_(2)CO_(3)],[H^(+)],[OH^(-)]and[CO_(3)^(2-)]with solution concentration c is plotted.From the diagram,we can directly observe which species are the major and which are the minor.In a high concentration,[H_(2)CO_(3)]≈[CO_(3)^(2-)]>>[OH^(-)]>>[H^(+)],indicating that the proton reactions which can produce H^(+)or OH^(-)are negligible,and HCO_(3)^(-)+HCO_(3)^(-)-H_(2)CO_(3)+CO_(3)^(2-)is the dominant.In 9.1×10^(-6) mol-L^(-1 )solution,[OH^(-)]≈[H_(2)CO_(3)]>>[H^(+)]≈[CO_(3)^(2-)],indicating that H_(2)O+HCO_(3)^(-)-H_(2)CO_(3)+OH^(-)is the dominant.In an extremely dilute solution,[OH^(-)]≈[H^(+)]>>[H_(2)CO_(3)]>[CO_(3)^(2-)],indicating that H_(2)O-H^(+)+OH^(-)dominates.

关 键 词：碳酸氢钠溶液 多重平衡 支配反应 反应产物含量图 

分 类 号：G64[文化科学—高等教育学] O6[文化科学—教育学]