Energy Changes

Contents & notes: what this topic covers

Under Energy Changes, the JAMB Chemistry syllabus expects you to study:

• 11. Energy Changes
• (a) Energy changes (∆H) accompanying physical and chemical changes: Dissolution of substances in/or reaction with water e.g. Na, NaOH, K, NH4Cl. Endothermic (+∆H) and exothermic (-∆H) reactions
• (b) Entropy as an order-disorder phenomenon: simple illustrations like mixing of gases and dissolution of salts
• (c) Spontaneity of reactions: ∆G0= 0 as a criterion for equilibrium, ∆G greater or less than zero as a criterion for non-spontaneity or spontaneity respectively

Study notes & guidance

Study Energy Changes using a recommended Chemistry textbook that follows the JAMB syllabus. Work through the contents listed above one by one, make brief notes in your own words, and then practise as many questions on this topic as you can — in Chemistry, understanding and steady practice matter far more than memorising. Use the objectives below as a checklist: if you can do each one confidently, you have mastered this topic.

Objectives — candidates should be able to

After studying Energy Changes, you should be able to:

1. (i) determine the types of heat changes (∆H) in physical and chemical processes; (ii) interpret graphical representations of heat changes; (iii) relate the physical state of a substance to the degree of orderliness; (iv) determine the conditions for spontaneity of a reaction ; (v) relate ∆H0, ∆S0 and ∆G0 as the driving forces for chemical reactions; and (vi) solve simple problems based on the relationships ∆G0= ∆H0 -T∆S0

These objectives are from the official JAMB syllabus. Use them as a checklist — if you can do each one confidently, you have mastered this topic.

Source: official JAMB UTME Chemistry syllabus (IBASS, jamb.gov.ng). Reproduced for study use. Last checked: 17 Sept 2026. Always confirm the current syllabus on the official portal.