Question detail

What is the stability order of carbocations?

Try the question, check the answer, then read the explanation to understand the curriculum point.

Show answer Topic hub Objective page

At a glance

MCQ

Type

practice

Style

Topic

Alkenes

Question

A. Tertiary > Secondary > Primary
B. Primary > Secondary > Tertiary
C. Secondary > Primary > Tertiary
D. All carbocations are equally stable.

Answer

Tertiary > Secondary > Primary

Explanation

The correct option is Tertiary > Secondary > Primary. Tertiary > Secondary > Primary is the best answer because it directly supports the AQA A-Level Chemistry objective to explain carbocation formation and stability where appropriate. This reasoning is anchored to Electrophilic addition in Alkenes, and it separates carbocation from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.

Common mistake

Misunderstanding Carbocation Stability

Students often confuse the stability of carbocations, thinking that all carbocations are equally stable regardless of their structure.

To explain carbocation stability, remember that tertiary carbocations are more stable than secondary, which are more stable than primary. This is due to the inductive effect and hyperconjugation from surrounding alkyl groups. For example, a tertiary carbocation (R3C+) is stabilized by three alkyl groups donating electron density, while a primary carbocation (RCH2+) is only stabilized by one. Thus, when predicting the major product of an electrophilic addition reaction, consider the stability of the carbocation formed during the reaction.

Related flashcards

Flashcard 1 of 5

Press Space to flip, arrows to move