Skip to main content
Ch. 4 - Acids and Bases: Electron Flow
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 3, Problem 25a

An unknown acid (HA) has been identified as very strong. What does this tell you about the stability of the conjugate base, A⁻? Is it strong or weak? Is it reactive or unreactive?

Verified step by step guidance
1
Understand the relationship between acid strength and conjugate base stability: A strong acid (HA) dissociates completely in water, meaning it donates its proton (H⁺) readily. This implies that its conjugate base (A⁻) must be very stable, as it does not readily reaccept the proton.
Recall the principle of conjugate acid-base pairs: The stronger the acid, the weaker its conjugate base. Since HA is identified as a very strong acid, its conjugate base (A⁻) is weak.
Analyze the reactivity of the conjugate base: A weak conjugate base is typically unreactive because it is stable and does not have a strong tendency to gain a proton or participate in other chemical reactions.
Consider the implications for chemical behavior: The stability of A⁻ means it is less likely to interfere in reactions or act as a nucleophile, making it unreactive in most contexts.
Summarize the findings: The conjugate base (A⁻) of a very strong acid (HA) is weak and unreactive due to its high stability.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Theory

Acid-base theory explains the behavior of acids and bases in terms of proton transfer. A strong acid, like the unknown acid HA, completely dissociates in solution, releasing protons (H⁺) and forming its conjugate base (A⁻). The strength of an acid is inversely related to the strength of its conjugate base; thus, a very strong acid indicates that its conjugate base is weak.
Recommended video:
Guided course
02:49
The Lewis definition of acids and bases.

Conjugate Base Stability

The stability of a conjugate base is crucial in determining the strength of its corresponding acid. A stable conjugate base (A⁻) is less likely to re-accept a proton, making the acid stronger. Factors influencing stability include electronegativity, resonance, and inductive effects; a weak conjugate base typically has lower stability, which aligns with the strong nature of the original acid.
Recommended video:
Guided course
04:31
Stability of Conjugated Intermediates

Reactivity of Conjugate Bases

The reactivity of a conjugate base is often linked to its stability. A weak conjugate base, such as A⁻ from a strong acid, is generally unreactive because it does not readily accept protons. This unreactivity stems from its stability, meaning it is less likely to participate in further acid-base reactions, contrasting with strong conjugate bases that are more reactive.
Recommended video:
Guided course
05:29
Definition of Conjugation