引用本文:
柳青, 刘建宇, 王海水. NaHCO3溶液浓度改变引起的支配质子转移反应变化:从HCO3-质子自递反应到HCO3-水解反应[J]. 大学化学,
2024, 39(1): 305-308.
doi:
10.3866/PKU.DXHX202305080
Citation: Qing Liu, Jianyu Liu, Haishui Wang. Shift of the Dominant Proton Transfer Reaction from Autoprotolysis of HCO3- to Hydrolysis of HCO3- Caused by Concentration Change of the NaHCO3 Solution[J]. University Chemistry, 2024, 39(1): 305-308. doi: 10.3866/PKU.DXHX202305080
Citation: Qing Liu, Jianyu Liu, Haishui Wang. Shift of the Dominant Proton Transfer Reaction from Autoprotolysis of HCO3- to Hydrolysis of HCO3- Caused by Concentration Change of the NaHCO3 Solution[J]. University Chemistry, 2024, 39(1): 305-308. doi: 10.3866/PKU.DXHX202305080
NaHCO3溶液浓度改变引起的支配质子转移反应变化:从HCO3-质子自递反应到HCO3-水解反应
摘要:
NaHCO3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H2CO3、H+、OH-和CO32-的相对含量也会发生变化。绘制了[H2CO3]、[H+]、[OH-]和[CO32-]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,[H2CO3] ≈ [CO32-]>> [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HCO3- + HCO3- ⇌ H2CO3+ CO32-占据支配地位。9.1×10-6 mol·L-1溶液中,[OH-] ≈ [H2CO3] >> [H+] ≈ [CO32-],表明质子反应H2O+ HCO3- ⇌ H2CO3+ OH-占据支配地位。极稀溶液中,[OH-] ≈ [H+] >> [H2CO3] > [CO32-],表明H2O ⇌ 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。
English
Shift of the Dominant Proton Transfer Reaction from Autoprotolysis of HCO3- to Hydrolysis of HCO3- Caused by Concentration Change of the NaHCO3 Solution
Abstract:
There are several proton transfer reactions and multiple chemical equilibria in NaHCO3 aqueous solution. As the concentration of the solution changes, the contents of H2CO3, H+, OH- and CO32-, which are related to proton transfer reactions, also change. The diagram of [H2CO3], [H+], [OH-] and [CO32-] 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, [H2CO3] ≈ [CO32-] >> [OH-] >> [H+], indicating that the proton reactions which can produce H+ or OH- are negligible, and HCO3- + HCO3- ⇌ H2CO3 + CO32- is the dominant. In 9.1×10-6 mol·L-1 solution, [OH-] ≈ [H2CO3] >> [H+] ≈ [CO32-], indicating that H2O + HCO3- ⇌ H2CO3 + OH- is the dominant. In an extremely dilute solution, [OH-] ≈ [H+] >> [H2CO3] > [CO32-], indicating that H2O ⇌ H+ + OH- dominates.
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