Acid-base theory
High School
Definition
The branch of chemistry concerned with acids and bases and how they react. In the Brønsted–Lowry model, an acid donates a proton (H⁺) and a base accepts one. For example, hydrochloric acid donates protons in water, making the solution acidic.
Worked examples
\(\)HCl\( + \)H\(_2\)O\( \)→\( \)H\(_3\)O\(^+ + \)Cl\(^-\)
HCl donates a proton to water, acting as a Brønsted–Lowry acid; water accepts it, acting as a base.
\(\)NH\(_3 + \)H\(_2\)O\( \)→\( \)NH\(_4^+ + \)OH\(^-\)
Ammonia accepts a proton from water, so ammonia is the base and water is the acid here.
Common mistakes
- Bases always contain OH⁻ ions → Bases are proton acceptors (Brønsted–Lowry); they don't need OH⁻ Ammonia (NH₃) is a base but has no hydroxide group—it accepts H⁺ from water.
- Water is always neutral in acid-base reactions → Water can act as an acid or a base depending on the other reactant Water is amphoteric—it donates H⁺ to strong bases and accepts H⁺ from strong acids.
- The acid is always the reactant with hydrogen in its formula → An acid is whichever species donates the proton in that reaction Water (H₂O) can be an acid when it donates H⁺ to ammonia, even though NH₃ also has hydrogen.
Where you'll use it next
You'll apply acid-base theory when studying pH calculations, buffer solutions, titrations, and equilibrium in chemistry, and later in biochemistry to understand enzyme function and metabolic pathways.
Found in 1 StudyPug lesson
Introduction to Acid-Base Theory: Unraveling Chemistry's Core Concepts
12th Grade12thChemistry 12
Dive into the world of acids and bases! Explore key models, understand pH scales, and discover real-world applications. Master this fundamental chemistry concept with our comprehensive guide.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026