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ChemistryAQA (7405) / Edexcel (9CH0)Energetics

Energetics & Enthalpy Calculator

AQA / Edexcel A-Level Chemistry

Energetics is a fundamental topic in A-Level Chemistry covering enthalpy changes, Hess's law, and bond enthalpy calculations. This interactive tool lets you construct enthalpy cycles, calculate enthalpy changes of reaction using Hess's law or mean bond enthalpies, and visualise energy profile diagrams for exothermic and endothermic reactions. Enter your own data to work through calorimetry calculations (q = mcΔT) and Born-Haber cycles. Aligned to both AQA and Edexcel specification requirements.

Uses Google Fonts (IBM Plex Mono, Plus Jakarta Sans). Requires an internet connection for full styling.

Frequently asked questions

What is Hess's law?+
Hess's law states that the total enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same. This allows you to calculate unknown enthalpy changes using enthalpy cycles with known values (e.g. enthalpies of formation or combustion).
How do you calculate enthalpy change using bond enthalpies?+
Sum the bond enthalpies of all bonds broken (endothermic, positive) and subtract the sum of all bond enthalpies of bonds formed (exothermic, negative). Delta H = sum of bonds broken minus sum of bonds formed.

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