Home › TYS Solutions › O Level Chem › 2025 › P1 Q31

2025 O Level Chem P1 Q31 — Energetics / Energy Profile Solution

Energetics / Energy Profile 2025 O Level Pure Chemistry · Paper 1 · Q31

Question

An energy profile diagram for a reaction is shown. Which statement about the diagram is correct? Question diagram

Question diagram

AThis is an exothermic reaction because more energy is released in making bonds than absorbed when breaking bonds.
BThis is an exothermic reaction because more energy is released when breaking bonds than absorbed in making bonds.
CThis is an endothermic reaction because more energy is released in making bonds than absorbed when breaking bonds.
DThis is an endothermic reaction because more energy is released when breaking bonds than absorbed in making bonds.

Correct answer: A

Video Solution

Explanation

Answer: A. Reactants are higher than products on the diagram, so the reaction is exothermic. Eliminate C and D (endothermic).

For an exothermic reaction, the energy released when product bonds are made exceeds the energy absorbed when reactant bonds are broken. The net difference (heat released) is \(\Delta H < 0\).

A states this correctly: 'more energy released making bonds than absorbed breaking bonds'.

B is wrong: it inverts the relationship ('released breaking bonds' is nonsensical — breaking bonds always absorbs energy).

Get the Sec 3 / Sec 4 recording package

Every O Level Pure Chemistry TYS MCQ solution video, plus full Sec 3 / Sec 4 topic recordings.