The acid base proton theory (Br ø nsted – Lowry acid base theory, Bronster Laurie acid base theory) was independently proposed by the Danish chemist J.N. Br ø nsted and the British chemist T.M. Lowry in 1923acid-base theory 。[1]Acid base proton theory is based onAcid-base ion theoryIt is developed on the basis of.
Chinese name
Acid base proton theory
Foreign name
Brönsted-Lowry acid-base theory
Alias
Bronst Laurie acid-base theory
creator
Bronst&Laurie
Year
1923
Features
Wide application range and quantitative processing
Acid-base ion theoryIt's Arrhenius according to hisIonization theoryProposed[2]。He thinks that in waterionizationOutHydrogen ionA substance that does not produce other cations is called acid.Can ionize out in waterHydroxyl ionAnd no otheranionThe substance is called alkali.acid-baseNeutralization reactionIn essence, hydrogen ions and hydroxyl ions combine to form water.This theory is classic, but because its description of acid and base is limited to aqueous solution, there are some limitations.For example, ammonium chloride aqueous solution is acidic, but it does not contain hydrogen ions;Another example is that the aqueous solution of ammonia is alkaline and was wrongly considered as NHthreeAnd HtwoO formationWeak electrolyteNHfourOH molecule, thendissociationOut of OH-Etc.
In 1923, Br ö nsted and Lowry put forward the acid-base proton theory because Arenius' acid-base ion theory could not solve some problems such as acid-base reactions in non-aqueous solutions.
Specific theoretical content
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Definition of acid-base
The proton theory put forward by Br ö nsted and Lowry in 1923 believed that when the proton (H+）Any substance (molecule or ion) ofacid；Where proton (H+）Any substance ofalkali。In short, acid is the donor of proton, while base is the acceptor of proton.The relationship between acid and base is shown as follows:
Acid=Proton (H+）+Alkali
According to the acid base proton theory, the acids include HCl, HAc, NHfour+、[Al(HtwoO)six]3+、HtwoPOfour-、HPOfour2-Etc.Alkali: NHthree、[Al(HtwoO)fiveOH]2+、Cl-、Ac-、HPOfour2-、POfour3-Etc.At the same time, it can be seen that acid and base are unified in the relationship with protons: acid becomes base after releasing protons, and base becomes acid after receiving protons.In order to express the relationship between them, the relationship between acid and base is often called conjugate acid base pair.The base formed after an acid emits protons is called the conjugate base of the acid;An acid formed after a base receives protons. It is calledConjugated acid。We call the corresponding acid and base that differ by one protonConjugated acid base pair。
Acid base strength
According to the proton theory of acids and bases, protons (H+）The substance is a strong acid, but it is not easy to form a base after it emits protons, and it has weak binding ability with protons, so it is a weak base.In other words, the stronger the acid, the weaker its conjugated base;On the contrary, the stronger the base, the weaker its conjugated acid.
According to the proton theory of acids and bases, the strength of acids and bases in solution is not only related to the nature of acids and bases, but also to the nature of solvents.What we can measure is the relative strength of acid and base in a certain solvent.If the same acid or base is dissolved in different solvents, their relative strength will be different.For example, HAc is weak acid in water, butliquid ammoniaIt shows strong acid, because the ability of liquid ammonia to capture protons (i.e. alkalinity) is much stronger than that of water.This phenomenon further explains the relativity of acid-base strength.
Progressive
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The acid-base proton theory expands the meaning of acid-base and the scope of acid-base reaction, gets rid of the limitation that acid-base must occur in water, and solves the problem of nonaqueous solutionOr acid-base reaction between gases, and dissociate, neutralizehydrolysisThe general situation of such reactions is one kind of reaction, namelyProton transferAcid base reaction of formula.However, the proton theory is limited to the release and acceptance of protons, so it must contain hydrogen and cannot explain the reaction of a class of compounds without hydrogen.It contains all alkaline substances and is still limited to hydrogen.
