Brønsted–Lowry Acid & Bases
Dr. Davinder Bhachu
Teacher
Contents
Introduction to Brønsted–Lowry Acids and Bases
Key Definitions
Brønsted–Lowry Acid: A substance that donates a proton .
Brønsted–Lowry Base: A substance that accepts a proton .
Think of acids as "proton donors" and bases as "proton acceptors".
Acid and Bases Explainer Video
Proton Transfer
In acid–base reactions, a proton is transferred from the acid to the base.
Example:
donates a proton acid
accepts a proton base
Conjugate Acid-Base Pairs
Acid–base reactions involve two pairs of species that differ by one proton . They can be interconverted by transfer of a proton.
Species | Acts As | Conjugate Pair |
Acid (donates ) | (conjugate base) | |
Base (accepts ) | (conjugate acid) |
General rule:
So:
Acid Conjugate base (loses )
Base Conjugate acid (gains )
No answer provided.
Strong vs Weak Acids/Bases
Type | Definition | Example | Dissociation |
Strong Acid | Fully dissociates in water | , | One-way arrow |
Weak Acid | Partially dissociates in water | Reversible arrow | |
Strong Base | Fully dissociates in water | ||
Weak Base | Partially dissociates in water |
Acid-Base Equilibria and Reversibility
In reactions involving weak acids or bases, equilibrium is established
Example:
Acid and conjugate bases are found on opposite sides of the equilibrium.
Worked Examples
Example 1: Identifying Acid and Base
Reaction:
Answer:
donates acid
accepts base
Conjugate pairs:
No answer provided.
Example 2: Writing Conjugate Pairs
Question: Write the conjugate acid of and the conjugate base of .
Answer:
Conjugate acid of
Conjugate base of
No answer provided.
Example 3: Equilibrium Reaction
Reaction:
Question: Identify the acid-base pairs in this equilibrium
Answer:
donates acid
accepts base
Conjugate acid-base pairs:
No answer provided.
Quick Recap Table
Term | Definition |
Brønsted–Lowry Acid | Proton donor |
Brønsted–Lowry Base | Proton acceptor |
Conjugate Acid | Base that has accepted an |
Conjugate Base | Acid that has lost an |
Strong Acid/Base | Fully dissociates in water |
Weak Acid/Base | Partially dissociates in water |
No answer provided.
Practice Questions
Question 1
Identify the Brønsted–Lowry acid and base:
Reaction:
Answer:
= acid (donates )
= base (accepts )
Conjugate pairs:
Question 2
Write the conjugate base of:
a)
b)
a)
b)
Question 3
Classify each as strong or weak acids:
a)
b)
a) Strong acid (fully dissociates)
b) Weak acid (partially dissociates)