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Ch.15 - Acid and Base EquilibriumWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch.17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Acids Introduction
Bases Introduction
Binary Acids
Amphoteric Species
Arrhenius Acids and Bases
Bronsted-Lowry Acids and Bases
Lewis Acids and Bases
The pH Scale
Ka and Kb
pH of Strong Acids and Bases
Ionic Salts
pH of Weak Acids
pH of Weak Bases
Diprotic Acids and Bases
Diprotic Acids and Bases Calculations
Triprotic Acids and Bases
Triprotic Acids and Bases Calculations
Additional Guides
Conjugate Acids and Bases
Jules Bruno

Conjugate acids and bases

In this guide, we take a look at what’s meant by a conjugate. Now, we have conjugate acids and conjugate bases. 

Conjugate acid

For a conjugate acid, all you’re going to do here is you’re going to add an H+ to the compound. It causes the charge to become more positive for that compound or element. For example, here we have hydrogen phosphate. We’re going to say here you’re starting off with a charge of minus 2. I’m going to add an H+ to it, so it becomes H2PO4. But remember, we’re not only adding a hydrogen, we’re adding a plus one charge to it as well. This is going to cause the charge to become more positive. We’re going to go from being -2 to being -1. Now we have dihydrogen phosphate which is H2PO4-. This would represent the conjugate acid of this compound here. 

Conjugate base

Conjugate base is the exact opposite. For conjugate base, all you do is remove an H+ from the compound causing its charge to become more negative. Here we have HS-. We’re going to remove an H+ from it. It started off as -1, but now it’s going to become more negative because you’re also losing a +1 as well as that hydrogen. Now it drops down to its new charge of 2-. This sulfide ion represents the conjugate base of HS-.


Remember, figuring out the conjugate acid or conjugate base of something is really simple if you just remember the following: Conjugate acid, you add an H+, the charge becomes more positive. Conjugate base, you remove an H+, charge becomes more negative for the compound or the element.

Jules Bruno

Jules felt a void in his life after his English degree from Duke, so he started tutoring in 2007 and got a B.S. in Chemistry from FIU. He’s exceptionally skilled at making concepts dead simple and helping students in covalent bonds of knowledge.