Beginner Topic 512 of 1102 Acids, Bases & Electrochemistry
Bronsted-Lowry Theory
Acids donate protons and bases accept protons.
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In-depth explanation of Bronsted-Lowry Theory
In the Bronsted-Lowry definition an acid is a proton donor and a base is a proton acceptor, so acid-base reactions become proton transfers that can occur in any solvent. Water is amphiprotic, able to act as either an acid or a base, which is why it appears on both sides of many equilibria. Every acid has a conjugate base formed by removing its proton, and every base has a conjugate acid formed by gaining one. The stronger the acid, the weaker its conjugate base, because a strong acid holds its proton loosely and its partner has little tendency to take it back. This theory underlies most pH and equilibrium calculations in aqueous chemistry.
Going deeper: Bronsted-Lowry Theory
Key ideas: An acid is a proton donor and a base a proton acceptor, so every reaction is a proton transfer between two conjugate pairs. To predict direction, compare acid strengths: equilibrium favors the side with the weaker acid and weaker base. Water acts as either role, which is why it is amphiprotic.
Common mistakes and connections: Students forget that a base needs a lone pair to bind H+. Also, a strong acid always has a weak conjugate base, but a weak acid does not have a strong conjugate base, only a modestly basic one. Links to Ka and Kb, conjugate pairs and the leveling effect.
Visualization of Bronsted-Lowry Theory
Ammonia accepts a proton from water to give the tetrahedral NH4+ ion, a Bronsted-Lowry proton transfer that needs no hydroxide in the base itself. The interactive lesson shows this as a live animation or chart.
Worked example and use case
In NH3 + H2O <-> NH4+ + OH-, NH3 accepts a proton and acts as the base, while H2O donates one and acts as the acid.
Frequently asked questions about Bronsted-Lowry Theory
What is Bronsted-Lowry Theory?
Acids donate protons and bases accept protons.
Is Bronsted-Lowry Theory a beginner, intermediate or advanced topic?
Bronsted-Lowry Theory is a beginner topic in Acids, Bases & Electrochemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Bronsted-Lowry Theory?
Study these earlier topics in Acids, Bases & Electrochemistry first: Arrhenius Acids and Bases.
What comes after Bronsted-Lowry Theory?
The next topics in Acids, Bases & Electrochemistry are Lewis Acids and Bases and Conjugate Acid-Base Pairs.
Can I practise Bronsted-Lowry Theory with quizzes?
Yes. The interactive lesson includes a self-check question on Bronsted-Lowry Theory, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Bronsted-Lowry Theory fits in Acids, Bases & Electrochemistry
Bronsted-Lowry Theory is topic 2 of 105 in Acids, Bases & Electrochemistry.